@article{ThiekenPisi2015, author = {Thieken, Annegret and Pisi, Sebastian}, title = {Entwicklungn der technischen Systeme und der Organisaton in der Warnkette seit 2002}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {123 -- 132}, year = {2015}, language = {de} } @article{KienzlerFalterThieken2015, author = {Kienzler, Sarah and Falter, Daniela and Thieken, Annegret}, title = {Zusammenwirken von staatlicher und privater Vorsorge}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {110 -- 120}, year = {2015}, language = {de} } @article{KienzlerPechThieken2015, author = {Kienzler, Sarah and Pech, Ina and Thieken, Annegret}, title = {Risikowahrnehmung, Risikokommunikation und Entwicklung der Eigenversorg von Betroffenen}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {99 -- 110}, year = {2015}, language = {de} } @article{PetrowThieken2015, author = {Petrow, Theresia and Thieken, Annegret}, title = {Entwicklunge in der Fl{\"a}chenvorsorge}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {92 -- 99}, year = {2015}, language = {de} } @article{SchroederHasanFalteretal.2015, author = {Schr{\"o}der, Kai and Hasan, Issa and Falter, Daniela and Thieken, Annegret}, title = {Schutz und Entlastung von hochwassergef{\"a}hrdeten Gebieten}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {76 -- 91}, year = {2015}, language = {de} } @article{Thieken2015, author = {Thieken, Annegret}, title = {Konzepte zur Umsetzung von Hochwasservorsorge und Risikomanagement}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {51 -- 65}, year = {2015}, language = {de} } @article{PetrowHasanOttoetal.2015, author = {Petrow, Theresia and Hasan, Issa and Otto, Antje and Thieken, Annegret}, title = {Entwicklungen in der Gesetzgebung zm Hochwasserrisikomanagment}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {47 -- 51}, year = {2015}, language = {de} } @article{MuellerBesselPisietal.2015, author = {M{\"u}ller, Meike and Bessel, Tina and Pisi, Sebastian and Kreibich, Heidi and Thieken, Annegret}, title = {Auswirkungen und Sch{\"a}den}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, isbn = {978-3-933181-62-6}, pages = {31 -- 45}, year = {2015}, language = {de} } @article{Thieken2015, author = {Thieken, Annegret}, title = {Einleitung}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {13 -- 17}, year = {2015}, language = {de} } @article{Thieken2015, author = {Thieken, Annegret}, title = {Danksagung}, series = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, journal = {Das Hochwasser im Juni 2013 : Bew{\"a}hrungsprobe f{\"u}r das Hochwasserrisikomanagement in Deutschland}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, pages = {11 -- 11}, year = {2015}, language = {de} } @book{ThiekenBesselCallsenetal.2015, author = {Thieken, Annegret and Bessel, Tina and Callsen, Ines and Falter, Daniela and Hasan, Issa and Kienzler, Sarah and Kox, Thomas and Kreibich, Heidi and Kuhlicke, Christian and Kunz, Michael and Matthias, Max and Meyer, Volker and M{\"u}hr, Bernhard and M{\"u}ller, Meike and Otto, Antje and Pech, Ina and Petrow, Theresia and Pisi, Sebastian and Rother, Karl-Heinz and Schr{\"o}ter, Kai}, title = {Das Hochwasser im Juni 2013}, series = {Schriftenreihe des DKKV ; 53}, journal = {Schriftenreihe des DKKV ; 53}, publisher = {Deutsches Komitee Katastrophenvorsorge}, address = {Bonn}, isbn = {978-3-933181-62-6}, publisher = {Universit{\"a}t Potsdam}, pages = {207}, year = {2015}, language = {de} } @phdthesis{Mueller2015, author = {M{\"u}ller, Eva Nora}, title = {The ecohydrological transfers, interactions and degradation arising from high-intensity storm events}, school = {Universit{\"a}t Potsdam}, pages = {224}, year = {2015}, language = {en} } @book{OPUS4-7857, title = {Wasser f{\"u}r Arkadien}, editor = {Schmitt, Hanno and Tosch, Frank}, publisher = {Rochow-Museum}, address = {Reckahn}, isbn = {978-3-9809752-7-8}, publisher = {Universit{\"a}t Potsdam}, pages = {135}, year = {2015}, abstract = {Begleitbuch zur Ausstellung im Rochow-Museum Reckahn, vom 6.6.-1.11.2015}, language = {de} } @phdthesis{Rohrmann2015, author = {Rohrmann, Alexander}, title = {The role of wind and water in shaping earth's plateaus}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-77938}, school = {Universit{\"a}t Potsdam}, pages = {XXV, 157}, year = {2015}, abstract = {The overarching goal of this dissertation is to provide a better understanding of the role of wind and water in shaping Earth's Cenozoic orogenic plateaus - prominent high-elevation, low relief sectors in the interior of Cenozoic mountain belts. In particular, the feedbacks between surface uplift, the build-up of topography and ensuing changes in precipitation, erosion, and vegetation patterns are addressed in light of past and future climate change. Regionally, the study focuses on the two world's largest plateaus, the Altiplano-Puna Plateau of the Andes and Tibetan Plateau, both characterized by average elevations of >4 km. Both plateaus feature high, deeply incised flanks with pronounced gradients in rainfall, vegetation, hydrology, and surface processes. These characteristics are rooted in the role of plateaus to act as efficient orographic barriers to rainfall and to force changes in atmospheric flow. The thesis examines the complex topics of tectonic and climatic forcing of the surface-process regime on three different spatial and temporal scales: (1) bedrock wind-erosion rates are quantified in the arid Qaidam Basin of NW Tibet over millennial timescales using cosmogenic radionuclide dating; (2) present-day stable isotope composition in rainfall is examined across the south-central Andes in three transects between 22° S and 28° S; these data are modeled and assessed with remotely sensed rainfall data of the Tropical Rainfall Measuring Mission and the Moderate Resolution Imaging Spectroradiometer; (3) finally, a 2.5-km-long Mio-Pliocene sedimentary record of the intermontane Angastaco Basin (25°45' S, 66°00' W) is presented in the context of hydrogen and carbon compositions of molecular lipid biomarker, and oxygen and carbon isotopes obtained from pedogenic carbonates; these records are compared to other environmental proxies, including hydrated volcanic glass shards from volcanic ashes intercalated in the sedimentary strata. There are few quantitative estimates of eolian bedrock-removal rates from arid, low relief landscapes. Wind-erosion rates from the western Qaidam Basin based on cosmogenic 10Be measurements document erosion rates between 0.05 to 0.4 mm/yr. This finding indicates that in arid environments with strong winds, hyperaridity, exposure of friable strata, and ongoing rock deformation and uplift, wind erosion can outpace fluvial erosion. Large eroded sediment volumes within the Qaidam Basin and coeval dust deposition on the Chinese Loess plateau, exemplify the importance of dust production within arid plateau environments for marine and terrestrial depositional processes, but also health issues and fertilization of soils. In the south-central Andes, the analysis of 234 stream-water samples for oxygen and hydrogen reveals that areas experiencing deep convective storms do not show the commonly observed patterns of isotopic fractionation and the expected co-varying relationships between oxygen and hydrogen with increasing elevation. These convective storms are formed over semi-arid intermontane basins in the transition between the broken foreland of the Sierras Pampeanas, the Eastern Cordillera, and the Puna Plateau in the interior of the orogen. Here, convective rainfall dominates the precipitation budget and no systematic stable isotope-elevation relationship exists. Regions to the north, in the transition between the broken foreland and the Subandean foreland fold-and-thrust belt, the impact of convection is subdued, with lower degrees of storminess and a stronger expected isotope-elevation relationship. This finding of present-day fractionation trends of meteoric water is of great importance for paleoenvironmental studies in attempts to use stable isotope relationships in the reconstruction of paleoelevations. The third part of the thesis focuses on the paleohydrological characteristics of the Mio-Pliocene (10-2 Ma) Angastaco Basin sedimentary record, which reveals far-reaching environmental changes during Andean uplift and orographic barrier formation. A precipitation- evapotranspiration record identifies the onset of a precipitation regime related to the South American Low Level Jet at this latitude after 9 Ma. Humid foreland conditions existed until 7 Ma, followed by orographic barrier uplift to the east of the present-day Angastaco Basin. This was superseded by rapid (~0.5 Myr) aridification in an intermontane basin, highlighting the effects of eastward-directed deformation. A transition in vegetation cover from a humid C3 forest ecosystem to semi-arid C4-dominated vegetation was coeval with continued basin uplift to modern elevations.}, language = {en} } @phdthesis{Pussak2014, author = {Pussak, Marcin}, title = {Seismic characterization of geothermal reservoirs by application of the common-reflection-surface stack method and attribute analysis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-77565}, school = {Universit{\"a}t Potsdam}, pages = {viii, 140}, year = {2014}, abstract = {An important contribution of geosciences to the renewable energy production portfolio is the exploration and utilization of geothermal resources. For the development of a geothermal project at great depths a detailed geological and geophysical exploration program is required in the first phase. With the help of active seismic methods high-resolution images of the geothermal reservoir can be delivered. This allows potential transport routes for fluids to be identified as well as regions with high potential of heat extraction to be mapped, which indicates favorable conditions for geothermal exploitation. The presented work investigates the extent to which an improved characterization of geothermal reservoirs can be achieved with the new methods of seismic data processing. The summations of traces (stacking) is a crucial step in the processing of seismic reflection data. The common-reflection-surface (CRS) stacking method can be applied as an alternative for the conventional normal moveout (NMO) or the dip moveout (DMO) stack. The advantages of the CRS stack beside an automatic determination of stacking operator parameters include an adequate imaging of arbitrarily curved geological boundaries, and a significant increase in signal-to-noise (S/N) ratio by stacking far more traces than used in a conventional stack. A major innovation I have shown in this work is that the quality of signal attributes that characterize the seismic images can be significantly improved by this modified type of stacking in particular. Imporoved attribute analysis facilitates the interpretation of seismic images and plays a significant role in the characterization of reservoirs. Variations of lithological and petro-physical properties are reflected by fluctuations of specific signal attributes (eg. frequency or amplitude characteristics). Its further interpretation can provide quality assessment of the geothermal reservoir with respect to the capacity of fluids within a hydrological system that can be extracted and utilized. The proposed methodological approach is demonstrated on the basis on two case studies. In the first example, I analyzed a series of 2D seismic profile sections through the Alberta sedimentary basin on the eastern edge of the Canadian Rocky Mountains. In the second application, a 3D seismic volume is characterized in the surroundings of a geothermal borehole, located in the central part of the Polish basin. Both sites were investigated with the modified and improved stacking attribute analyses. The results provide recommendations for the planning of future geothermal plants in both study areas.}, language = {en} } @phdthesis{Reiter2014, author = {Reiter, Karsten}, title = {Crustal stress variability across spatial scales - examples from Canada, Northern Switzerland and a South African gold mine}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76762}, school = {Universit{\"a}t Potsdam}, pages = {VIII, 149, XI}, year = {2014}, abstract = {The quantitative descriptions of the state of stress in the Earth's crust, and spatial-temporal stress changes are of great importance in terms of scientific questions as well as applied geotechnical issues. Human activities in the underground (boreholes, tunnels, caverns, reservoir management, etc.) have a large impact on the stress state. It is important to assess, whether these activities may lead to (unpredictable) hazards, such as induced seismicity. Equally important is the understanding of the in situ stress state in the Earth's crust, as it allows the determination of safe well paths, already during well planning. The same goes for the optimal configuration of the injection- and production wells, where stimulation for artificial fluid path ways is necessary. The here presented cumulative dissertation consists of four separate manuscripts, which are already published, submitted or will be submitted for peer review within the next weeks. The main focus is on the investigation of the possible usage of geothermal energy in the province Alberta (Canada). A 3-D geomechanical-numerical model was designed to quantify the contemporary 3-D stress tensor in the upper crust. For the calibration of the regional model, 321 stress orientation data and 2714 stress magnitude data were collected, whereby the size and diversity of the database is unique. A calibration scheme was developed, where the model is calibrated versus the in situ stress data stepwise for each data type and gradually optimized using statistically test methods. The optimum displacement on the model boundaries can be determined by bivariate linear regression, based on only three model runs with varying deformation ratio. The best-fit model is able to predict most of the in situ stress data quite well. Thus, the model can provide the full stress tensor along any chosen virtual well paths. This can be used to optimize the orientation of horizontal wells, which e.g. can be used for reservoir stimulation. The model confirms regional deviations from the average stress orientation trend, such as in the region of the Peace River Arch and the Bow Island Arch. In the context of data compilation for the Alberta stress model, the Canadian database of the World Stress Map (WSM) could be expanded by including 514 new data records. This publication of an update of the Canadian stress map after ~20 years with a specific focus on Alberta shows, that the maximum horizontal stress (SHmax) is oriented southwest to northeast over large areas in Northern America. The SHmax orientation in Alberta is very homogeneous, with an average of about 47°. In order to calculate the average SHmax orientation on a regular grid as well as to estimate the wave-length of stress orientation, an existing algorithm has been improved and is applied to the Canadian data. The newly introduced quasi interquartile range on the circle (QIROC) improves the variance estimation of periodic data, as it is less susceptible to its outliers. Another geomechanical-numerical model was built to estimate the 3D stress tensor in the target area "N{\"o}rdlich L{\"a}gern" in Northern Switzerland. This location, with Opalinus clay as a host rock, is a potential repository site for high-level radioactive waste. The performed modelling aims to investigate the sensitivity of the stress tensor on tectonic shortening, topography, faults and variable rock properties within the Mesozoic sedimentary stack, according to the required stability needed for a suitable radioactive waste disposal site. The majority of the tectonic stresses caused by the far-field shortening from the South are admitted by the competent rock units in the footwall and hanging wall of the argillaceous target horizon, the Upper Malm and Upper Muschelkalk. Thus, the differential stress within the host rock remains relatively low. East-west striking faults release stresses driven by tectonic shortening. The purely gravitational influence by the topography is low; higher SHmax magnitudes below topographical depression and lower values below hills are mainly observed near the surface. A complete calibration of the model is not possible, as no stress magnitude data are available for calibration, yet. The collection of this data will begin in 2015; subsequently they will be used to adjust the geomechanical-numerical model again. The third geomechanical-numerical model investigates the stress variation in an ultra-deep gold mine in South Africa. This reservoir model is spatially one order of magnitude smaller than the previous local model from Northern Switzerland. Here, the primary focus is to investigate the hypothesis that the Mw 1.9 earthquake on 27 December 2007 was induced by stress changes due to the mining process. The Coulomb failure stress change (DeltaCFS) was used to analyse the stress change. It confirmed that the seismic event was induced by static stress transfer due to the mining progress. The rock was brought closer to failure on the derived rupture plane by stress changes of up to 1.5-15MPa, in dependence of the DeltaCFS analysis type. A forward modelling of a generic excavation scheme reveals that with decreasing distance to the dyke the DeltaCFS values increase significantly. Hence, even small changes in the mining progress can have a significant impact on the seismic hazard risk, i.e. the change of the occurrence probability to induce a seismic event of economic concern.}, language = {en} } @phdthesis{Busch2015, author = {Busch, Jan Philip}, title = {Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76873}, school = {Universit{\"a}t Potsdam}, pages = {X, 127, XLIII}, year = {2015}, abstract = {Injection of nanoscale zero-valent iron (nZVI) is an innovative technology for in situ installation of a permeable reactive barrier in the subsurface. Zerovalent iron (ZVI) is highly reactive with chlorinated hydrocarbons (CHCs) and renders them into less harmful substances. Application of nZVI instead of granular ZVI can increase rates of dechlorination of CHCs by orders of magnitude, due to its higher surface area. This approach is still difficult to apply due to fast agglomeration and sedimentation of colloidal suspensions of nZVI, which leads to very short transport distances. To overcome this issue of limited mobility, polyanionic stabilisers are added to increase surface charge and stability of suspensions. In field experiments maximum transport distances of a few metres were achieved. A new approach, which is investigated in this thesis, is enhanced mobility of nZVI by a more mobile carrier colloid. The investigated composite material consists of activated carbon, which is loaded with nZVI. In this cumulative thesis, transport characteristics of carbon-colloid supported nZVI (c-nZVI) are investigated. Investigations started with column experiments in 40 cm columns filled with various porous media to investigate on physicochemical influences on transport characteristics. The experimental setup was enlarged to a transport experiment in a 1.2-m-sized two-dimensional aquifer tank experiment, which was filled with granular porous media. Further, a field experiment was performed in a natural aquifer system with a targeted transport distance of 5.3 m. Parallel to these investigations, alternative methods for transport observations were investigated by using noninvasive tomographic methods. Experiments using synchrotron radiation and magnetic resonance (MRI) were performed to investigate in situ transport characteristics in a non-destructive way. Results from column experiments show potentially high mobility under environmental relevant conditions. Addition of mono-and bivalent salts, e.g. more than 0.5 mM/L CaCl2, might decrease mobility. Changes in pH to values below 6 can inhibit mobility at all. Measurements of colloid size show changes in the mean particle size by a factor of ten. Measurements of zeta potential revealed an increase of -62 mV to -82 mV. Results from the 2D-aquifer test system suggest strong particle deposition in the first centimetres and only weak straining in the further travel path and no gravitational influence on particle transport. Straining at the beginning of the travel path in the porous medium was observed with tomographic investigations of transport. MRI experiments revealed similar results to the previous experiments, and observations using synchrotron radiation suggest straining of colloids at pore throats. The potential for high transport distances, which was suggested from laboratory experiments, was confirmed in the field experiment, where the transport distance of 5.3 m was reached by at least 10\% of injected nZVI. Altogether, transport distances of the investigated carbon-colloid supported nZVI are higher than published results of traditional nZVI.}, language = {en} } @phdthesis{Sen2014, author = {Sen, Ali Tolga}, title = {Inversion of seismic source parameters for weak mining-induced and natural earthquakes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71914}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The purpose of this thesis is to develop an automated inversion scheme to derive point and finite source parameters for weak earthquakes, here intended with the unusual meaning of earthquakes with magnitudes at the limit or below the bottom magnitude threshold of standard source inversion routines. The adopted inversion approaches entirely rely on existing inversion software, the methodological work mostly targeting the development and tuning of optimized inversion flows. The resulting inversion scheme is tested for very different datasets, and thus allows the discussion on the source inversion problem at different scales. In the first application, dealing with mining induced seismicity, the source parameters determination is addressed at a local scale, with source-sensor distance of less than 3 km. In this context, weak seismicity corresponds to event below magnitude MW 2.0, which are rarely target of automated source inversion routines. The second application considers a regional dataset, namely the aftershock sequence of the 2010 Maule earthquake (Chile), using broadband stations at regional distances, below 300 km. In this case, the magnitude range of the target aftershocks range down to MW 4.0. This dataset is here considered as a weak seismicity case, since the analysis of such moderate seismicity is generally investigated only by moment tensor inversion routines, with no attempt to resolve source duration or finite source parameters. In this work, automated multi-step inversion schemes are applied to both datasets with the aim of resolving point source parameters, both using double couple (DC) and full moment tensor (MT) models, source duration and finite source parameters. A major result of the analysis of weaker events is the increased size of resulting moment tensor catalogues, which interpretation may become not trivial. For this reason, a novel focal mechanism clustering approach is used to automatically classify focal mechanisms, allowing the investigation of the most relevant and repetitive rupture features. The inversion of the mining induced seismicity dataset reveals the repetitive occurrence of similar rupture processes, where the source geometry is controlled by the shape of the mined panel. Moreover, moment tensor solutions indicate a significant contribution of tensile processes. Also the second application highlights some characteristic geometrical features of the fault planes, which show a general consistency with the orientation of the slab. The additional inversion for source duration allowed to verify the empirical correlation for moment normalized earthquakes in subduction zones among a decreasing rupture duration with increasing source depth, which was so far only observed for larger events.}, language = {en} } @phdthesis{Cao2014, author = {Cao, Xianyong}, title = {Vegetation and climate change in eastern continental Asia during the last 22 ka inferred from pollen data synthesis}, pages = {156}, year = {2014}, language = {en} } @phdthesis{Sarkar2014, author = {Sarkar, Saswati}, title = {Holocene variations in the strength of the Indian Monsoon system}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-74905}, school = {Universit{\"a}t Potsdam}, pages = {ix, 114}, year = {2014}, abstract = {The monsoon is an important component of the Earth's climate system. It played a vital role in the development and sustenance of the largely agro-based economy in India. A better understanding of past variations in the Indian Summer Monsoon (ISM) is necessary to assess its nature under global warming scenarios. Instead, our knowledge of spatiotemporal patterns of past ISM strength, as inferred from proxy records, is limited due to the lack of high-resolution paleo-hydrological records from the core monsoon domain. In this thesis I aim to improve our understanding of Holocene ISM variability from the core 'monsoon zone' (CMZ) in India. To achieve this goal, I tried to understand modern and thereafter reconstruct Holocene monsoonal hydrology, by studying surface sediments and a high-resolution sedimentary record from the saline-alkaline Lonar crater lake, central India. My approach relies on analyzing stable carbon and hydrogen isotope ratios from sedimentary lipid biomarkers to track past hydrological changes. In order to evaluate the relationship of the modern ecosystem and hydrology of the lake I studied the distribution of lipid biomarkers in the modern ecosystem and compared it to lake surface sediments. The major plants from dry deciduous mixed forest type produced a greater amount of leaf wax n-alkanes and a greater fraction of n-C31 and n-C33 alkanes relative to n-C27 and n-C29. Relatively high average chain length (ACL) values (29.6-32.8) for these plants seem common for vegetation from an arid and warm climate. Additionally I found that human influence and subsequent nutrient supply result in increased lake primary productivity, leading to an unusually high concentration of tetrahymanol, a biomarker for salinity and water column stratification, in the nearshore sediments. Due to this inhomogeneous deposition of tetrahymanol in modern sediments, I hypothesize that lake level fluctuation may potentially affect aquatic lipid biomarker distributions in lacustrine sediments, in addition to source changes. I reconstructed centennial-scale hydrological variability associated with changes in the intensity of the ISM based on a record of leaf wax and aquatic biomarkers and their stable carbon (δ13C) and hydrogen (δD) isotopic composition from a 10 m long sediment core from the lake. I identified three main periods of distinct hydrology over the Holocene in central India. The period between 10.1 and 6 cal. ka BP was likely the wettest during the Holocene. Lower ACL index values (29.4 to 28.6) of leaf wax n-alkanes and their negative δ13C values (-34.8 per mille to -27.8 per mille) indicated the dominance of woody C3 vegetation in the catchment, and negative δDwax (average for leaf wax n-alkanes) values (-171 per mille to -147 per mille) argue for a wet period due to an intensified monsoon. After 6 cal. ka BP, a gradual shift to less negative δ13C values (particularly for the grass derived n-C31) and appearance of the triterpene lipid tetrahymanol, generally considered as a marker for salinity and water column stratification, marked the onset of drier conditions. At 5.1 cal. ka BP increasing flux of leaf wax n-alkanes along with the highest flux of tetrahymanol indicated proximity of the lakeshore to the center due to a major lake level decrease. Rapid fluctuations in abundance of both terrestrial and aquatic biomarkers between 4.8 and 4 cal. ka BP indicated an unstable lake ecosystem, culminating in a transition to arid conditions. A pronounced shift to less negative δ13C values, in particular for n-C31 (-25.2 per mille to -22.8 per mille), over this period indicated a change of dominant vegetation to C4 grasses. Along with a 40 per mille increase in leaf wax n-alkane δD values, which likely resulted from less rainfall and/or higher plant evapotranspiration, I interpret this period to reflect the driest conditions in the region during the last 10.1 ka. This transition led to protracted late Holocene arid conditions and the establishment of a permanently saline lake. This is supported by the high abundance of tetrahymanol. A late Holocene peak of cyanobacterial biomarker input at 1.3 cal. ka BP might represent an event of lake eutrophication, possibly due to human impact and the onset of cattle/livestock farming in the catchment. The most intriguing feature of the mid-Holocene driest period was the high amplitude and rapid fluctuations in δDwax values, probably due to a change in the moisture source and/or precipitation seasonality. I hypothesize that orbital induced weakening of the summer solar insolation and associated reorganization of the general atmospheric circulation were responsible for an unstable hydroclimate in the mid-Holocene in the CMZ. My findings shed light onto the sequence of changes during mean state changes of the monsoonal system, once an insolation driven threshold has been passed, and show that small changes in solar insolation can be associated to major environmental changes and large fluctuations in moisture source, a scenario that may be relevant with respect to future changes in the ISM system.}, language = {en} } @phdthesis{Borchardt2014, author = {Borchardt, Sven}, title = {Rainfall, weathering and erosion}, pages = {x, 90}, year = {2014}, language = {en} } @phdthesis{Feld2014, author = {Feld, Christian}, title = {Crustal structure of the Eratosthenes Seamount, Cyprus and S. Turkey from an amphibian wide-angle seismic profile}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-73479}, school = {Universit{\"a}t Potsdam}, pages = {xi, 131}, year = {2014}, abstract = {In March 2010, the project CoCoCo (incipient COntinent-COntinent COllision) recorded a 650 km long amphibian N-S wide-angle seismic profile, extending from the Eratosthenes Seamount (ESM) across Cyprus and southern Turkey to the Anatolian plateau. The aim of the project is to reveal the impact of the transition from subduction to continent-continent collision of the African plate with the Cyprus-Anatolian plate. A visual quality check, frequency analysis and filtering were applied to the seismic data and reveal a good data quality. Subsequent first break picking, finite-differences ray tracing and inversion of the offshore wide-angle data leads to a first-arrival tomographic model. This model reveals (1) P-wave velocities lower than 6.5 km/s in the crust, (2) a variable crustal thickness of about 28 - 37 km and (3) an upper crustal reflection at 5 km depth beneath the ESM. Two land shots on Turkey, also recorded on Cyprus, airgun shots south of Cyprus and geological and previous seismic investigations provide the information to derive a layered velocity model beneath the Anatolian plateau and for the ophiolite complex on Cyprus. The analysis of the reflections provides evidence for a north-dipping plate subducting beneath Cyprus. The main features of this layered velocity model are (1) an upper and lower crust with large lateral changes of the velocity structure and thickness, (2) a Moho depth of about 38 - 45 km beneath the Anatolian plateau, (3) a shallow north-dipping subducting plate below Cyprus with an increasing dip and (4) a typical ophiolite sequence on Cyprus with a total thickness of about 12 km. The offshore-onshore seismic data complete and improve the information about the velocity structure beneath Cyprus and the deeper part of the offshore tomographic model. Thus, the wide-angle seismic data provide detailed insights into the 2-D geometry and velocity structures of the uplifted and overriding Cyprus-Anatolian plate. Subsequent gravity modelling confirms and extends the crustal P-wave velocity model. The deeper part of the subducting plate is constrained by the gravity data and has a dip angle of ~ 28°. Finally, an integrated analysis of the geophysical and geological information allows a comprehensive interpretation of the crustal structure related to the collision process.}, language = {en} } @phdthesis{Tympel2014, author = {Tympel, Jens G{\"u}nter}, title = {Numerical modeling of the Cenozoic Pamir-Tien Shan orogeny}, pages = {168}, year = {2014}, language = {en} } @phdthesis{Munack2014, author = {Munack, Henry}, title = {From phantom blocks to denudational noise}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-72629}, school = {Universit{\"a}t Potsdam}, pages = {xvii, 172}, year = {2014}, abstract = {Knowing the rates and mechanisms of geomorphic process that shape the Earth's surface is crucial to understand landscape evolution. Modern methods for estimating denudation rates enable us to quantitatively express and compare processes of landscape downwearing that can be traced through time and space—from the seemingly intact, though intensely shattered, phantom blocks of the catastrophically fragmented basal facies of giant rockslides up to denudational noise in orogen-wide data sets averaging over several millennia. This great variety of spatiotemporal scales of denudation rates is both boon and bane of geomorphic process rates. Indeed, processes of landscape downwearing can be traced far back in time, helping us to understand the Earth's evolution. Yet, this benefit may turn into a drawback due to scaling issues if these rates are to be compared across different observation timescales. This thesis investigates the mechanisms, patterns and rates of landscape downwearing across the Himalaya-Tibet orogen. Accounting for the spatiotemporal variability of denudation processes, this thesis addresses landscape downwearing on three distinctly different spatial scales, starting off at the local scale of individual hillslopes where considerable amounts of debris are generated from rock instantaneously: Rocksliding in active mountains is a major impetus of landscape downwearing. Study I provides a systematic overview of the internal sedimentology of giant rockslide deposits and thus meets the challenge of distinguishing them from macroscopically and microscopically similar glacial deposits, tectonic fault-zone breccias, and impact breccias. This distinction is important to avoid erroneous or misleading deduction of paleoclimatic or tectonic implications. -> Grain size analysis shows that rockslide-derived micro-breccia closely resemble those from meteorite impact or tectonic faults. -> Frictionite may occur more frequently that previously assumed. -> M{\"o}ssbauer-spectroscopy derived results indicate basal rock melting in the absence of water, involving short-term temperatures of >1500°C. Zooming out, Study II tracks the fate of these sediments, using the example of the upper Indus River, NW India. There we use river sand samples from the Indus and its tributaries to estimate basin-averaged denudation rates along a ~320-km reach across the Tibetan Plateau margin, to answer the question whether incision into the western Tibetan Plateau margin is currently active or not. -> We find an about one-order-of-magnitude upstream decay—from 110 to 10 mm kyr^-1—of cosmogenic Be-10-derived basin-wide denudation rates across the morphological knickpoint that marks the transition from the Transhimalayan ranges to the Tibetan Plateau. This trend is corroborated by independent bulk petrographic and heavy mineral analysis of the same samples. -> From the observation that tributary-derived basin-wide denudation rates do not increase markedly until ~150-200 km downstream of the topographic plateau margin we conclude that incision into the Tibetan Plateau is inactive. -> Comparing our postglacial Be-10-derived denudation rates to long-term (>10^6 yr) estimates from low-temperature thermochronometry, ranging from 100 to 750 mm kyr^-1, points to an order- of-magnitude decay of rates of landscape downwearing towards present. We infer that denudation rates must have been higher in the Quaternary, probably promoted by the interplay of glacial and interglacial stages. Our investigation of regional denudation patterns in the upper Indus finally is an integral part of Study III that synthesizes denudation of the Himalaya-Tibet orogen. In order to identify general and time-invariant predictors for Be-10-derived denudation rates we analyze tectonic, climatic and topographic metrics from an inventory of 297 drainage basins from various parts of the orogen. Aiming to get insight to the full response distributions of denudation rate to tectonic, climatic and topographic candidate predictors, we apply quantile regression instead of ordinary least squares regression, which has been standard analysis tool in previous studies that looked for denudation rate predictors. -> We use principal component analysis to reduce our set of 26 candidate predictors, ending up with just three out of these: Aridity Index, topographic steepness index, and precipitation of the coldest quarter of the year. -> Topographic steepness index proves to perform best during additive quantile regression. Our consequent prediction of denudation rates on the basin scale involves prediction errors that remain between 5 and 10 mm kyr^-1. -> We conclude that while topographic metrics such as river-channel steepness and slope gradient—being representative on timescales that our cosmogenic Be-10-derived denudation rates integrate over—generally appear to be more suited as predictors than climatic and tectonic metrics based on decadal records.}, language = {en} } @phdthesis{Sayago2014, author = {Sayago, Jhosnella}, title = {Late Paleozoic basin analysis of the Loppa High and Finnmark Platform in the Norwegian Barents Sea : integration of seismic attributes and seismic sequence stratigraphy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72576}, school = {Universit{\"a}t Potsdam}, pages = {viii, 109}, year = {2014}, abstract = {The subsurface upper Palaeozoic sedimentary successions of the Loppa High half-graben and the Finnmark platform in the Norwegian Barents Sea (southwest Barents Sea) were investigated using 2D/3D seismic datasets combined with well and core data. These sedimentary successions represent a case of mixed siliciclastic-carbonates depositional systems, which formed during the earliest phase of the Atlantic rifting between Greenland and Norway. During the Carboniferous and Permian the southwest part of the Barents Sea was located along the northern margin of Pangaea, which experienced a northward drift at a speed of ~2-3 mm per year. This gradual shift in the paleolatitudinal position is reflected by changes in regional climatic conditions: from warm-humid in the early Carboniferous, changing to warm-arid in the middle to late Carboniferous and finally to colder conditions in the late Permian. Such changes in paleolatitude and climate have resulted in major changes in the style of sedimentation including variations in the type of carbonate factories. The upper Palaeozoic sedimentary succession is composed of four major depositional units comprising chronologically the Billefjorden Group dominated by siliciclastic deposition in extensional tectonic-controlled wedges, the Gipsdalen Group dominated by warm-water carbonates, stacked buildups and evaporites, the Bjarmeland Group characterized by cool-water carbonates as well as by the presence of buildup networks, and the Tempelfjorden Group characterized by fine-grained sedimentation dominated by biological silica production. In the Loppa High, the integration of a core study with multi-attribute seismic facies classification allowed highlighting the main sedimentary unconformities and mapping the spatial extent of a buried paleokarst terrain. This geological feature is interpreted to have formed during a protracted episode of subaerial exposure occurring between the late Palaeozoic and middle Triassic. Based on seismic sequence stratigraphy analysis the palaeogeography in time and space of the Loppa High basin was furthermore reconstructed and a new and more detailed tectono-sedimentary model for this area was proposed. In the Finnmark platform area, a detailed core analysis of two main exploration wells combined with key 2D seismic sections located along the main depositional profile, allowed the evaluation of depositional scenarios for the two main lithostratigraphic units: the {\O}rn Formation (Gipsdalen Group) and the Isbj{\o}rn Formation (Bjarmeland Group). During the mid-Sakmarian, two major changes were observed between the two formations including (1) the variation in the type of the carbonate factories, which is interpreted to be depth-controlled and (2) the change in platform morphology, which evolved from a distally steepened ramp to a homoclinal ramp. The results of this study may help supporting future reservoirs characterization of the upper Palaeozoic units in the Barents Sea, particularly in the Loppa High half-graben and the Finmmark platform area.}, language = {en} } @phdthesis{Schollaen2014, author = {Schollaen, Karina}, title = {Tracking climate signals in tropical trees}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71947}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The tropical warm pool waters surrounding Indonesia are one of the equatorial heat and moisture sources that are considered as a driving force of the global climate system. The climate in Indonesia is dominated by the equatorial monsoon system, and has been linked to El Ni{\~n}o-Southern Oscillation (ENSO) events, which often result in severe droughts or floods over Indonesia with profound societal and economic impacts on the populations living in the world's fourth most populated country. The latest IPCC report states that ENSO will remain the dominant mode in the tropical Pacific with global effects in the 21st century and ENSO-related precipitation extremes will intensify. However, no common agreement exists among climate simulation models for projected change in ENSO and the Australian-Indonesian Monsoon. Exploring high-resolution palaeoclimate archives, like tree rings or varved lake sediments, provide insights into the natural climate variability of the past, and thus helps improving and validating simulations of future climate changes. Centennial tree-ring stable isotope records | Within this doctoral thesis the main goal was to explore the potential of tropical tree rings to record climate signals and to use them as palaeoclimate proxies. In detail, stable carbon (δ13C) and oxygen (δ18O) isotopes were extracted from teak trees in order to establish the first well-replicated centennial (AD 1900-2007) stable isotope records for Java, Indonesia. Furthermore, different climatic variables were tested whether they show significant correlation with tree-ring proxies (ring-width, δ13C, δ18O). Moreover, highly resolved intra-annual oxygen isotope data were established to assess the transfer of the seasonal precipitation signal into the tree rings. Finally, the established oxygen isotope record was used to reveal possible correlations with ENSO events. Methodological achievements | A second goal of this thesis was to assess the applicability of novel techniques which facilitate and optimize high-resolution and high-throughput stable isotope analysis of tree rings. Two different UV-laser-based microscopic dissection systems were evaluated as a novel sampling tool for high-resolution stable isotope analysis. Furthermore, an improved procedure of tree-ring dissection from thin cellulose laths for stable isotope analysis was designed. The most important findings of this thesis are: I) The herein presented novel sampling techniques improve stable isotope analyses for tree-ring studies in terms of precision, efficiency and quality. The UV-laser-based microdissection serve as a valuable tool for sampling plant tissue at ultrahigh-resolution and for unprecedented precision. II) A guideline for a modified method of cellulose extraction from wholewood cross-sections and subsequent tree-ring dissection was established. The novel technique optimizes the stable isotope analysis process in two ways: faster and high-throughput cellulose extraction and precise tree-ring separation at annual to high-resolution scale. III) The centennial tree-ring stable isotope records reveal significant correlation with regional precipitation. High-resolution stable oxygen values, furthermore, allow distinguishing between dry and rainy season rainfall. IV) The δ18O record reveals significant correlation with different ENSO flavors and demonstrates the importance of considering ENSO flavors when interpreting palaeoclimatic data in the tropics. The findings of my dissertation show that seasonally resolved δ18O records from Indonesian teak trees are a valuable proxy for multi-centennial reconstructions of regional precipitation variability (monsoon signals) and large-scale ocean-atmosphere phenomena (ENSO) for the Indo-Pacific region. Furthermore, the novel methodological achievements offer many unexplored avenues for multidisciplinary research in high-resolution palaeoclimatology.}, language = {en} } @phdthesis{Muksin2014, author = {Muksin, Umar}, title = {A fault-controlled geothermal system in Tarutung (North Sumatra, Indonesia)investigated by seismological analysis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72065}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The seismic structure (Vp, Vp/Vs, and Qp anomalies) contributes to the physical properties and the lithology of rocks and possible fluid distribution in the region. The Vp model images the geometry of the Tarutung and the Sarulla basins. Both basins have a depth of around 2.0 km. High Vp/Vs and high attenuation (low Qp) anomalies are observed along the Sarulla graben associated with a weak zone caused by volcanic activities along the graben. Low Vp/Vs and low conductivity anomalies are found in the west of the Tarutung basin. This anomaly is interpreted as dry, compact, and rigid granitic rock in the region as also found by geological observations. Low Vp, high Vp/Vs and low Qp anomalies are found at the east of the Tarutung basin which appear to be associated with the three big geothermal manifestations in Sipoholon, Hutabarat, and Panabungan area. These anomalies are connected with high Vp/Vs and low Qp anomalies below the Tarutung basin at depth of around 3 - 10 km. This suggests that these geothermal manifestations are fed by the same source of the hot fluid below the Tarutung basin. The hot fluids from below the Tarutung basin propagate to the more dilatational and more permeable zone in the northeast. Granite found in the west of the Tarutung basin could also be abundant underneath the basin at a certain depth so that it prevents the hot fluid to be transported directly to the Tarutung basin. High seismic attenuation and low Vp/Vs anomalies are found in the southwest of the Tarutung basin below the Martimbang volcano. These anomalies are associated with hot rock below the volcano without or with less amount of partial melting. There is no indication that the volcano controls the geothermal system around the Tarutung basin. The geothermal resources around the Tarutung basin is a fault-controlled system as a result of deep circulation of fluids. Outside of the basin, the seismicity delineation and the focal mechanism correlate with the shape and the characteristics of the strike-slip Sumatran fault. Within the Tarutung basin, the seismicity is distributed more broadly which coincides with the margin of the basin. An extensional duplex system in the Tarutung basin is derived from the seismicity and focal mechanism analysis which is also consistent with the geological observations. The vertical distribution of the seismicity suggests the presence of a negative flower structure within the Tarutung basin.}, language = {de} } @phdthesis{Radeff2014, author = {Radeff, Giuditta}, title = {Geohistory of the Central Anatolian Plateau southern margin (southern Turkey)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71865}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The Adana Basin of southern Turkey, situated at the SE margin of the Central Anatolian Plateau is ideally located to record Neogene topographic and tectonic changes in the easternmost Mediterranean realm. Using industry seismic reflection data we correlate 34 seismic profiles with corresponding exposed units in the Adana Basin. The time-depth conversion of the interpreted seismic profiles allows us to reconstruct the subsidence curve of the Adana Basin and to outline the occurrence of a major increase in both subsidence and sedimentation rates at 5.45 - 5.33 Ma, leading to the deposition of almost 1500 km3 of conglomerates and marls. Our provenance analysis of the conglomerates reveals that most of the sediment is derived from and north of the SE margin of the Central Anatolian Plateau. A comparison of these results with the composition of recent conglomerates and the present drainage basins indicates major changes between late Messinian and present-day source areas. We suggest that these changes in source areas result of uplift and ensuing erosion of the SE margin of the plateau. This hypothesis is supported by the comparison of the Adana Basin subsidence curve with the subsidence curve of the Mut Basin, a mainly Neogene basin located on top of the Central Anatolian Plateau southern margin, showing that the Adana Basin subsidence event is coeval with an uplift episode of the plateau southern margin. The collection of several fault measurements in the Adana region show different deformation styles for the NW and SE margins of the Adana Basin. The weakly seismic NW portion of the basin is characterized by extensional and transtensional structures cutting Neogene deposits, likely accomodating the differential uplift occurring between the basin and the SE margin of the plateau. We interpret the tectonic evolution of the southern flank of the Central Anatolian Plateau and the coeval subsidence and sedimentation in the Adana Basin to be related to deep lithospheric processes, particularly lithospheric delamination and slab break-off.}, language = {en} } @phdthesis{Bach2013, author = {Bach, Christoph}, title = {Improving statistical seismicity models}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70591}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Several mechanisms are proposed to be part of the earthquake triggering process, including static stress interactions and dynamic stress transfer. Significant differences of these mechanisms are particularly expected in the spatial distribution of aftershocks. However, testing the different hypotheses is challenging because it requires the consideration of the large uncertainties involved in stress calculations as well as the appropriate consideration of secondary aftershock triggering which is related to stress changes induced by smaller pre- and aftershocks. In order to evaluate the forecast capability of different mechanisms, I take the effect of smaller--magnitude earthquakes into account by using the epidemic type aftershock sequence (ETAS) model where the spatial probability distribution of direct aftershocks, if available, is correlated to alternative source information and mechanisms. Surface shaking, rupture geometry, and slip distributions are tested. As an approximation of the shaking level, ShakeMaps are used which are available in near real-time after a mainshock and thus could be used for first-order forecasts of the spatial aftershock distribution. Alternatively, the use of empirical decay laws related to minimum fault distance is tested and Coulomb stress change calculations based on published and random slip models. For comparison, the likelihood values of the different model combinations are analyzed in the case of several well-known aftershock sequences (1992 Landers, 1999 Hector Mine, 2004 Parkfield). The tests show that the fault geometry is the most valuable information for improving aftershock forecasts. Furthermore, they reveal that static stress maps can additionally improve the forecasts of off--fault aftershock locations, while the integration of ground shaking data could not upgrade the results significantly. In the second part of this work, I focused on a procedure to test the information content of inverted slip models. This allows to quantify the information gain if this kind of data is included in aftershock forecasts. For this purpose, the ETAS model based on static stress changes, which is introduced in part one, is applied. The forecast ability of the models is systematically tested for several earthquake sequences and compared to models using random slip distributions. The influence of subfault resolution and segment strike and dip is tested. Some of the tested slip models perform very good, in that cases almost no random slip models are found to perform better. Contrastingly, for some of the published slip models, almost all random slip models perform better than the published slip model. Choosing a different subfault resolution hardly influences the result, as long the general slip pattern is still reproducible. Whereas different strike and dip values strongly influence the results depending on the standard deviation chosen, which is applied in the process of randomly selecting the strike and dip values.}, language = {en} } @phdthesis{Bathke2014, author = {Bathke, Hannes}, title = {An investigation of complex deformation patterns detected by using InSAR at Llaima and Tend{\"u}rek volcanoes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70522}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Surface displacement at volcanic edifices is related to subsurface processes associated with magma movements, fluid transfers within the volcano edifice and gravity-driven deformation processes. Understanding of associated ground displacements is of importance for assessment of volcanic hazards. For example, volcanic unrest is often preceded by surface uplift, caused by magma intrusion and followed by subsidence, after the withdrawal of magma. Continuous monitoring of the surface displacement at volcanoes therefore might allow the forecasting of upcoming eruptions to some extent. In geophysics, the measured surface displacements allow the parameters of possible deformation sources to be estimated through analytical or numerical modeling. This is one way to improve the understanding of subsurface processes acting at volcanoes. Although the monitoring of volcanoes has significantly improved in the last decades (in terms of technical advancements and number of monitored volcanoes), the forecasting of volcanic eruptions remains puzzling. In this work I contribute towards the understanding of the subsurface processes at volcanoes and thus to the improvement of volcano eruption forecasting. I have investigated the displacement field of Llaima volcano in Chile and of Tend{\"u}rek volcano in East Turkey by using synthetic aperture radar interferometry (InSAR). Through modeling of the deformation sources with the extracted displacement data, it was possible to gain insights into potential subsurface processes occurring at these two volcanoes that had been barely studied before. The two volcanoes, although of very different origin, composition and geometry, both show a complexity of interacting deformation sources. At Llaima volcano, the InSAR technique was difficult to apply, due to the large decorrelation of the radar signal between the acquisition of images. I developed a model-based unwrapping scheme, which allows the production of reliable displacement maps at the volcano that I used for deformation source modeling. The modeling results show significant differences in pre- and post-eruptive magmatic deformation source parameters. Therefore, I conjecture that two magma chambers exist below Llaima volcano: a post-eruptive deep one and a shallow one possibly due to the pre-eruptive ascent of magma. Similar reservoir depths at Llaima have been confirmed by independent petrologic studies. These reservoirs are interpreted to be temporally coupled. At Tend{\"u}rek volcano I have found long-term subsidence of the volcanic edifice, which can be described by a large, magmatic, sill-like source that is subject to cooling contraction. The displacement data in conjunction with high-resolution optical images, however, reveal arcuate fractures at the eastern and western flank of the volcano. These are most likely the surface expressions of concentric ring-faults around the volcanic edifice that show low magnitudes of slip over a long time. This might be an alternative mechanism for the development of large caldera structures, which are so far assumed to be generated during large catastrophic collapse events. To investigate the potential subsurface geometry and relation of the two proposed interacting sources at Tend{\"u}rek, a sill-like magmatic source and ring-faults, I have performed a more sophisticated numerical modeling approach. The optimum source geometries show, that the size of the sill-like source was overestimated in the simple models and that it is difficult to determine the dip angle of the ring-faults with surface displacement data only. However, considering physical and geological criteria a combination of outward-dipping reverse faults in the west and inward-dipping normal faults in the east seem to be the most likely. Consequently, the underground structure at the Tend{\"u}rek volcano consists of a small, sill-like, contracting, magmatic source below the western summit crater that causes a trapdoor-like faulting along the ring-faults around the volcanic edifice. Therefore, the magmatic source and the ring-faults are also interpreted to be temporally coupled. In addition, a method for data reduction has been improved. The modeling of subsurface deformation sources requires only a relatively small number of well distributed InSAR observations at the earth's surface. Satellite radar images, however, consist of several millions of these observations. Therefore, the large amount of data needs to be reduced by several orders of magnitude for source modeling, to save computation time and increase model flexibility. I have introduced a model-based subsampling approach in particular for heterogeneously-distributed observations. It allows a fast calculation of the data error variance-covariance matrix, also supports the modeling of time dependent displacement data and is, therefore, an alternative to existing methods.}, language = {en} } @phdthesis{Nikolaeva2013, author = {Nikolaeva, Elena}, title = {Landslide kinematics and interactions studied in central Georgia by using synthetic aperture radar interferometry, optical imagery and inverse modeling}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70406}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Landslides are one of the biggest natural hazards in Georgia, a mountainous country in the Caucasus. So far, no systematic monitoring and analysis of the dynamics of landslides in Georgia has been made. Especially as landslides are triggered by extrinsic processes, the analysis of landslides together with precipitation and earthquakes is challenging. In this thesis I describe the advantages and limits of remote sensing to detect and better understand the nature of landslide in Georgia. The thesis is written in a cumulative form, composing a general introduction, three manuscripts and a summary and outlook chapter. In the present work, I measure the surface displacement due to active landslides with different interferometric synthetic aperture radar (InSAR) methods. The slow landslides (several cm per year) are well detectable with two-pass interferometry. In same time, the extremely slow landslides (several mm per year) could be detected only with time series InSAR techniques. I exemplify the success of InSAR techniques by showing hitherto unknown landslides, located in the central part of Georgia. Both, the landslide extent and displacement rate is quantified. Further, to determine a possible depth and position of potential sliding planes, inverse models were developed. Inverse modeling searches for parameters of source which can create observed displacement distribution. I also empirically estimate the volume of the investigated landslide using displacement distributions as derived from InSAR combined with morphology from an aerial photography. I adapted a volume formula for our case, and also combined available seismicity and precipitation data to analyze potential triggering factors. A governing question was: What causes landslide acceleration as observed in the InSAR data? The investigated area (central Georgia) is seismically highly active. As an additional product of the InSAR data analysis, a deformation area associated with the 7th September Mw=6.0 earthquake was found. Evidences of surface ruptures directly associated with the earthquake could not be found in the field, however, during and after the earthquake new landslides were observed. The thesis highlights that deformation from InSAR may help to map area prone landslides triggering by earthquake, potentially providing a technique that is of relevance for country wide landslide monitoring, especially as new satellite sensors will emerge in the coming years.}, language = {en} } @phdthesis{Grigoli2014, author = {Grigoli, Francesco}, title = {Automated seismic event location by waveform coherence analysis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70329}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Automated location of seismic events is a very important task in microseismic monitoring operations as well for local and regional seismic monitoring. Since microseismic records are generally characterised by low signal-to-noise ratio, such methods are requested to be noise robust and sufficiently accurate. Most of the standard automated location routines are based on the automated picking, identification and association of the first arrivals of P and S waves and on the minimization of the residuals between theoretical and observed arrival times of the considered seismic phases. Although current methods can accurately pick P onsets, the automatic picking of the S onset is still problematic, especially when the P coda overlaps the S wave onset. In this thesis I developed a picking free automated method based on the Short-Term-Average/Long-Term-Average (STA/LTA) traces at different stations as observed data. I used the STA/LTA of several characteristic functions in order to increase the sensitiveness to the P wave and the S waves. For the P phases we use the STA/LTA traces of the vertical energy function, while for the S phases, we use the STA/LTA traces of the horizontal energy trace and then a more optimized characteristic function which is obtained using the principal component analysis technique. The orientation of the horizontal components can be retrieved by robust and linear approach of waveform comparison between stations within a network using seismic sources outside the network (chapter 2). To locate the seismic event, we scan the space of possible hypocentral locations and origin times, and stack the STA/LTA traces along the theoretical arrival time surface for both P and S phases. Iterating this procedure on a three-dimensional grid we retrieve a multidimensional matrix whose absolute maximum corresponds to the spatial and temporal coordinates of the seismic event. Location uncertainties are then estimated by perturbing the STA/LTA parameters (i.e the length of both long and short time windows) and relocating each event several times. In order to test the location method I firstly applied it to a set of 200 synthetic events. Then we applied it to two different real datasets. A first one related to mining induced microseismicity in a coal mine in the northern Germany (chapter 3). In this case we successfully located 391 microseismic event with magnitude range between 0.5 and 2.0 Ml. To further validate the location method I compared the retrieved locations with those obtained by manual picking procedure. The second dataset consist in a pilot application performed in the Campania-Lucania region (southern Italy) using a 33 stations seismic network (Irpinia Seismic Network) with an aperture of about 150 km (chapter 4). We located 196 crustal earthquakes (depth < 20 km) with magnitude range 1.1 < Ml < 2.7. A subset of these locations were compared with accurate locations retrieved by a manual location procedure based on the use of a double difference technique. In both cases results indicate good agreement with manual locations. Moreover, the waveform stacking location method results noise robust and performs better than classical location methods based on the automatic picking of the P and S waves first arrivals.}, language = {en} } @phdthesis{Mohr2013, author = {Mohr, Christian Heinrich}, title = {Hydrological and erosion responses to man-made and natural disturbances : insights from forested catchments in South-central Chile}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70146}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Logging and large earthquakes are disturbances that may significantly affect hydrological and erosional processes and process rates, although in decisively different ways. Despite numerous studies that have documented the impacts of both deforestation and earthquakes on water and sediment fluxes, a number of details regarding the timing and type of de- and reforestation; seismic impacts on subsurface water fluxes; or the overall geomorphic work involved have remained unresolved. The main objective of this thesis is to address these shortcomings and to better understand and compare the hydrological and erosional process responses to such natural and man-made disturbances. To this end, south-central Chile provides an excellent natural laboratory owing to its high seismicity and the ongoing conversion of land into highly productive plantation forests. In this dissertation I combine paired catchment experiments, data analysis techniques, and physics-based modelling to investigate: 1) the effect of plantation forests on water resources, 2) the source and sink behavior of timber harvest areas in terms of overland flow generation and sediment fluxes, 3) geomorphic work and its efficiency as a function of seasonal logging, 4) possible hydrologic responses of the saturated zone to the 2010 Maule earthquake and 5) responses of the vadose zone to this earthquake. Re 1) In order to quantify the hydrologic impact of plantation forests, it is fundamental to first establish their water balances. I show that tree species is not significant in this regard, i.e. Pinus radiata and Eucalyptus globulus do not trigger any decisive different hydrologic response. Instead, water consumption is more sensitive to soil-water supply for the local hydro-climatic conditions. Re 2) Contradictory opinions exist about whether timber harvest areas (THA) generate or capture overland flow and sediment. Although THAs contribute significantly to hydrology and sediment transport because of their spatial extent, little is known about the hydrological and erosional processes occurring on them. I show that THAs may act as both sources and sinks for overland flow, which in turn intensifies surface erosion. Above a rainfall intensity of ~20 mm/h, which corresponds to <10\% of all rainfall, THAs may generate runoff whereas below that threshold they remain sinks. The overall contribution of Hortonian runoff is thus secondary considering the local rainfall regime. The bulk of both runoff and sediment is generated by Dunne, saturation excess, overland flow. I also show that logging may increase infiltrability on THAs which may cause an initial decrease in streamflow followed by an increase after the groundwater storage has been refilled. Re 3) I present changes in frequency-magnitude distributions following seasonal logging by applying Quantile Regression Forests at hitherto unprecedented detail. It is clearly the season that controls the hydro-geomorphic work efficiency of clear cutting. Logging, particularly dry seasonal logging, caused a shift of work efficiency towards less flashy and mere but more frequent moderate rainfall-runoff events. The sediment transport is dominated by Dunne overland flow which is consistent with physics-based modelling using WASA-SED. Re 4) It is well accepted that earthquakes may affect hydrological processes in the saturated zone. Assuming such flow conditions, consolidation of saturated saprolitic material is one possible response. Consolidation raises the hydraulic gradients which may explain the observed increase in discharge following earthquakes. By doing so, squeezed water saturates the soil which in turn increases the water accessible for plant transpiration. Post-seismic enhanced transpiration is reflected in the intensification of diurnal cycling. Re 5) Assuming unsaturated conditions, I present the first evidence that the vadose zone may also respond to seismic waves by releasing pore water which in turn feeds groundwater reservoirs. By doing so, water tables along the valley bottoms are elevated thus providing additional water resources to the riparian vegetation. By inverse modelling, the transient increase in transpiration is found to be 30-60\%. Based on the data available, both hypotheses, are not testable. Finally, when comparing the hydrological and erosional effects of the Maule earthquake with the impact of planting exotic plantation forests, the overall observed earthquake effects are comparably small, and limited to short time scales.}, language = {en} } @phdthesis{Buchhorn2013, author = {Buchhorn, Marcel}, title = {Ground-based hyperspectral and spectro-directional reflectance characterization of Arctic tundra vegetation communities : field spectroscopy and field spectro-goniometry of Siberian and Alaskan tundra in preparation of the EnMAP satellite mission}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70189}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The Arctic tundra, covering approx. 5.5 \% of the Earth's land surface, is one of the last ecosystems remaining closest to its untouched condition. Remote sensing is able to provide information at regular time intervals and large spatial scales on the structure and function of Arctic ecosystems. But almost all natural surfaces reveal individual anisotropic reflectance behaviors, which can be described by the bidirectional reflectance distribution function (BRDF). This effect can cause significant changes in the measured surface reflectance depending on solar illumination and sensor viewing geometries. The aim of this thesis is the hyperspectral and spectro-directional reflectance characterization of important Arctic tundra vegetation communities at representative Siberian and Alaskan tundra sites as basis for the extraction of vegetation parameters, and the normalization of BRDF effects in off-nadir and multi-temporal remote sensing data. Moreover, in preparation for the upcoming German EnMAP (Environmental Mapping and Analysis Program) satellite mission, the understanding of BRDF effects in Arctic tundra is essential for the retrieval of high quality, consistent and therefore comparable datasets. The research in this doctoral thesis is based on field spectroscopic and field spectro-goniometric investigations of representative Siberian and Alaskan measurement grids. The first objective of this thesis was the development of a lightweight, transportable, and easily managed field spectro-goniometer system which nevertheless provides reliable spectro-directional data. I developed the Manual Transportable Instrument platform for ground-based Spectro-directional observations (ManTIS). The outcome of the field spectro-radiometrical measurements at the Low Arctic study sites along important environmental gradients (regional climate, soil pH, toposequence, and soil moisture) show that the different plant communities can be distinguished by their nadir-view reflectance spectra. The results especially reveal separation possibilities between the different tundra vegetation communities in the visible (VIS) blue and red wavelength regions. Additionally, the near-infrared (NIR) shoulder and NIR reflectance plateau, despite their relatively low values due to the low structure of tundra vegetation, are still valuable information sources and can separate communities according to their biomass and vegetation structure. In general, all different tundra plant communities show: (i) low maximum NIR reflectance; (ii) a weakly or nonexistent visible green reflectance peak in the VIS spectrum; (iii) a narrow "red-edge" region between the red and NIR wavelength regions; and (iv) no distinct NIR reflectance plateau. These common nadir-view reflectance characteristics are essential for the understanding of the variability of BRDF effects in Arctic tundra. None of the analyzed tundra communities showed an even closely isotropic reflectance behavior. In general, tundra vegetation communities: (i) usually show the highest BRDF effects in the solar principal plane; (ii) usually show the reflectance maximum in the backward viewing directions, and the reflectance minimum in the nadir to forward viewing directions; (iii) usually have a higher degree of reflectance anisotropy in the VIS wavelength region than in the NIR wavelength region; and (iv) show a more bowl-shaped reflectance distribution in longer wavelength bands (>700 nm). The results of the analysis of the influence of high sun zenith angles on the reflectance anisotropy show that with increasing sun zenith angles, the reflectance anisotropy changes to azimuthally symmetrical, bowl-shaped reflectance distributions with the lowest reflectance values in the nadir view position. The spectro-directional analyses also show that remote sensing products such as the NDVI or relative absorption depth products are strongly influenced by BRDF effects, and that the anisotropic characteristics of the remote sensing products can significantly differ from the observed BRDF effects in the original reflectance data. But the results further show that the NDVI can minimize view angle effects relative to the contrary spectro-directional effects in the red and NIR bands. For the researched tundra plant communities, the overall difference of the off-nadir NDVI values compared to the nadir value increases with increasing sensor viewing angles, but on average never exceeds 10 \%. In conclusion, this study shows that changes in the illumination-target-viewing geometry directly lead to an altering of the reflectance spectra of Arctic tundra communities according to their object-specific BRDFs. Since the different tundra communities show only small, but nonetheless significant differences in the surface reflectance, it is important to include spectro-directional reflectance characteristics in the algorithm development for remote sensing products.}, language = {en} } @phdthesis{Vogel2013, author = {Vogel, Kristin}, title = {Applications of Bayesian networks in natural hazard assessments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69777}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Even though quite different in occurrence and consequences, from a modeling perspective many natural hazards share similar properties and challenges. Their complex nature as well as lacking knowledge about their driving forces and potential effects make their analysis demanding: uncertainty about the modeling framework, inaccurate or incomplete event observations and the intrinsic randomness of the natural phenomenon add up to different interacting layers of uncertainty, which require a careful handling. Nevertheless deterministic approaches are still widely used in natural hazard assessments, holding the risk of underestimating the hazard with disastrous effects. The all-round probabilistic framework of Bayesian networks constitutes an attractive alternative. In contrast to deterministic proceedings, it treats response variables as well as explanatory variables as random variables making no difference between input and output variables. Using a graphical representation Bayesian networks encode the dependency relations between the variables in a directed acyclic graph: variables are represented as nodes and (in-)dependencies between variables as (missing) edges between the nodes. The joint distribution of all variables can thus be described by decomposing it, according to the depicted independences, into a product of local conditional probability distributions, which are defined by the parameters of the Bayesian network. In the framework of this thesis the Bayesian network approach is applied to different natural hazard domains (i.e. seismic hazard, flood damage and landslide assessments). Learning the network structure and parameters from data, Bayesian networks reveal relevant dependency relations between the included variables and help to gain knowledge about the underlying processes. The problem of Bayesian network learning is cast in a Bayesian framework, considering the network structure and parameters as random variables itself and searching for the most likely combination of both, which corresponds to the maximum a posteriori (MAP score) of their joint distribution given the observed data. Although well studied in theory the learning of Bayesian networks based on real-world data is usually not straight forward and requires an adoption of existing algorithms. Typically arising problems are the handling of continuous variables, incomplete observations and the interaction of both. Working with continuous distributions requires assumptions about the allowed families of distributions. To "let the data speak" and avoid wrong assumptions, continuous variables are instead discretized here, thus allowing for a completely data-driven and distribution-free learning. An extension of the MAP score, considering the discretization as random variable as well, is developed for an automatic multivariate discretization, that takes interactions between the variables into account. The discretization process is nested into the network learning and requires several iterations. Having to face incomplete observations on top, this may pose a computational burden. Iterative proceedings for missing value estimation become quickly infeasible. A more efficient albeit approximate method is used instead, estimating the missing values based only on the observations of variables directly interacting with the missing variable. Moreover natural hazard assessments often have a primary interest in a certain target variable. The discretization learned for this variable does not always have the required resolution for a good prediction performance. Finer resolutions for (conditional) continuous distributions are achieved with continuous approximations subsequent to the Bayesian network learning, using kernel density estimations or mixtures of truncated exponential functions. All our proceedings are completely data-driven. We thus avoid assumptions that require expert knowledge and instead provide domain independent solutions, that are applicable not only in other natural hazard assessments, but in a variety of domains struggling with uncertainties.}, language = {en} } @phdthesis{Cherubini2013, author = {Cherubini, Yvonne}, title = {Influence of faults on the 3D coupled fluid and heat transport}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69755}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Da geologische St{\"o}rungen k{\"o}nnen als Grundwasserleiter, -Barrieren oder als gemischte leitende /stauende Fluidsysteme wirken. Aufgrund dessen k{\"o}nnen St{\"o}rungen maßgeblich den Grundwasserfluss im Untergrund beeinflussen, welcher deutliche Ver{\"a}nderungen des tiefen thermischen Feldes bewirken kann. Grundwasserdynamik und Temperaturver{\"a}nderungen sind wiederum entscheidende Faktoren f{\"u}r die Exploration geothermischer Energie. Diese Studie untersuchte den Einfluss von St{\"o}rungen auf das Fluidsystem und das thermische Feld im Untergrund. Sie erforschte die physikalischen Prozesse, welche das Fluidverhalten und die Temperaturverteilung in St{\"o}rungen und in den umgebenden Gesteinen. Dazu wurden 3D Finite Elemente Simulationen des gekoppelten Fluid und W{\"a}rmetransports f{\"u}r synthetische sowie reale Modelszenarien auf unterschiedlichen Skalen durchgef{\"u}hrt. Um den Einfluss einer schr{\"a}g einfallenden St{\"o}rung systematisch durch die schrittweise Ver{\"a}nderung der hydraulischen {\"O}ffnungsweite und der Permeabilit{\"a}t, zu untersuchen, wurde ein klein-skaliges synthetisches Modell entwickelt. Ein inverser linearer Zusammenhang wurde festgestellt, welcher zeigt, dass sich die Fluidgeschwindigkeit in der St{\"o}rung jeweils um ~1e-01 m/s verringert, wenn die {\"O}ffnungsweite der St{\"o}rung um jeweils eine Magnitude vergr{\"o}ßert wird. Ein hoher Permeabilit{\"a}tskontrast zwischen St{\"o}rung und umgebender Matrix beg{\"u}nstigt die Fluidadvektion hin zur St{\"o}rung und f{\"u}hrt zu ausgepr{\"a}gten Druck- und Temperaturver{\"a}nderungen innerhalb und um die St{\"o}rung herum. Bei geringem Permeabilit{\"a}tskontrast zwischen St{\"o}rung und umgebendem Gestein findet hingegen kein Fluidfluss in der St{\"o}rung statt, wobei das hydrostatische Druck- sowie das Temperaturfeld unver{\"a}ndert bleiben. Auf Grundlage der synthetischen Modellierungsergebnisse wurde der Einfluss von St{\"o}rungen auf einer gr{\"o}ßeren Skala anhand eines komplexeren (realen) geologischen Systems analysiert. Dabei handelt es sich um ein 3D Modell des Geothermiestandortes Groß Sch{\"o}nebeck, der ca. 40 km n{\"o}rdlich von Berlin liegt. Die Integration von einer permeablen und drei impermeablen Hauptst{\"o}rungen, zeigte unterschiedlich starke Einfl{\"u}sse auf Fluidzirkulation, Temperatur - und Druckfeld. Die modellierte konvektive Zirkulation in der permeablen St{\"o}rung ver{\"a}ndert das thermische Feld stark (bis zu 15 K). In den gering durchl{\"a}ssigen St{\"o}rungen wird die W{\"a}rme ausschließlich durch Diffusion geleitet. Der konduktive W{\"a}rmetransport beeinflusst das thermische Feld nicht, bewirkt jedoch lokale Ver{\"a}nderungen des hydrostatischen Druckfeldes. Um den Einfluss großer St{\"o}rungszonen mit kilometerweitem vertikalen Versatz auf das geothermische Feld der Beckenskala zu untersuchen, wurden gekoppelte Fluid- und W{\"a}rmetransportsimulationen f{\"u}r ein 3D Strukturmodell des Gebietes Brandenburg durchgef{\"u}hrt (Noack et al. 2010; 2013). Bez{\"u}glich der St{\"o}rungspermeabilit{\"a}t wurden verschiedene geologische Szenarien modelliert, von denen zwei Endgliedermodelle ausgewertet wurden. Die Ergebnisse zeigten, dass die undurchl{\"a}ssigen St{\"o}rungen den Fluidfluss nur lokal beeinflussen. Da sie als hydraulische Barrieren wirken, wird der Fluidfluss mir sehr geringen Geschwindigkeiten entlang der St{\"o}rungen innerhalb eines Bereichs von ~ 1 km auf jeder Seite umgelenkt. Die modellierten lokalen Ver{\"a}nderungen des Grundwasserzirkulationssystems haben keinen beobachtbaren Effekt auf das Temperaturfeld. Hingegen erzeugen permeable St{\"o}rungszonen eine ausgepr{\"a}gte thermische Signatur innerhalb eines Einflussbereichs von ~ 2.4-8.8 km in -1000 m Tiefe und ~6-12 km in -3000 m Tiefe. Diese thermische Signatur, in der sich k{\"a}ltere und w{\"a}rmere Temperaturbereiche abwechseln, wird durch auf- und abw{\"a}rts gerichteten Fluidfluss innerhalb der St{\"o}rung verursacht, der grunds{\"a}tzlich durch existierende Gradienten in der hydraulischen Druckh{\"o}he angetrieben wird. Alle Studien haben gezeigt, dass St{\"o}rungen einen beachtlichen Einfluss auf den Fluid-, und W{\"a}rmefluss haben. Es stellte sich heraus, dass die Permeabilit{\"a}t in der St{\"o}rung und in den umgebenden geologischen Schichten so wie der spezifische geologische Rahmen entscheidende Faktoren in der Ausbildung verschiedener W{\"a}rmetransportmechanismen sind, die sich in St{\"o}rungen entwickeln k{\"o}nnen. Die von permeablen St{\"o}rungen verursachten Temperaturver{\"a}nderungen k{\"o}nnen lokal, jedoch groß sein, genauso wie die durch hydraulisch leitende und nichtleitende St{\"o}rungen hervorgerufenen Ver{\"a}nderungen des Fluidystems. Letztlich haben die Simulationen f{\"u}r die unterschiedlich skalierten Modelle gezeigt, dass die Ergebnisse sich nicht aufeinander {\"u}bertragen lassen und dass es notwendig ist, jeden geologischen Rahmen hinsichtlich Konfiguration und Gr{\"o}ßenskala gesondert zu betrachten. Abschließend hat diese Studie demonstriert, dass die Betrachtung von St{\"o}rungen in 3D Finiten Elementen Modellen f{\"u}r die Simulation von gekoppeltem Fluid- und W{\"a}rmetransport auf unterschiedlichen Skalen m{\"o}glich ist. Da diese Art von numerischen Simulationen sowohl die geologische Struktur des Untergrunds sowie die im Erdinnern ablaufenden physikalischen Prozesse integriert, k{\"o}nnen sie einen wertvollen Beitrag leisten, indem sie Feld- und Laborgest{\"u}tzte Untersuchungen vervollst{\"a}ndigen.}, language = {de} } @phdthesis{Schuetz2013, author = {Sch{\"u}tz, Felina}, title = {Surface heat flow and lithospheric thermal structure of the northwestern Arabian Plate}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69622}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The surface heat flow (qs) is paramount for modeling the thermal structure of the lithosphere. Changes in the qs over a distinct lithospheric unit are normally directly reflecting changes in the crustal composition and therewith the radiogenic heat budget (e.g., Rudnick et al., 1998; F{\"o}rster and F{\"o}rster, 2000; Mareschal and Jaupart, 2004; Perry et al., 2006; Hasterok and Chapman, 2011, and references therein) or, less usual, changes in the mantle heat flow (e.g., Pollack and Chapman, 1977). Knowledge of this physical property is therefore of great interest for both academic research and the energy industry. The present study focuses on the qs of central and southern Israel as part of the Sinai Microplate (SM). Having formed during Oligocene to Miocene rifting and break-up of the African and Arabian plates, the SM is characterized by a young and complex tectonic history. Resulting from the time thermal diffusion needs to pass through the lithosphere, on the order of several tens-of-millions of years (e.g., Fowler, 1990); qs-values of the area reflect conditions of pre-Oligocene times. The thermal structure of the lithosphere beneath the SM in general, and south-central Israel in particular, has remained poorly understood. To address this problem, the two parameters needed for the qs determination were investigated. Temperature measurements were made at ten pre-existing oil and water exploration wells, and the thermal conductivity of 240 drill core and outcrop samples was measured in the lab. The thermal conductivity is the sensitive parameter in this determination. Lab measurements were performed on both, dry and water-saturated samples, which is labor- and time-consuming. Another possibility is the measurement of thermal conductivity in dry state and the conversion to a saturated value by using mean model approaches. The availability of a voluminous and diverse dataset of thermal conductivity values in this study allowed (1) in connection with the temperature gradient to calculate new reliable qs values and to use them to model the thermal pattern of the crust in south-central Israel, prior to young tectonic events, and (2) in connection with comparable datasets, controlling the quality of different mean model approaches for indirect determination of bulk thermal conductivity (BTC) of rocks. The reliability of numerically derived BTC values appears to vary between different mean models, and is also strongly dependent upon sample lithology. Yet, correction algorithms may significantly reduce the mismatch between measured and calculated conductivity values based on the different mean models. Furthermore, the dataset allowed the derivation of lithotype-specific conversion equations to calculate the water-saturated BTC directly from data of dry-measured BTC and porosity (e.g., well log derived porosity) with no use of any mean model and thus provide a suitable tool for fast analysis of large datasets. The results of the study indicate that the qs in the study area is significantly higher than previously assumed. The new presented qs values range between 50 and 62 mW m⁻². A weak trend of decreasing heat flow can be identified from the east to the west (55-50 mW m⁻²), and an increase from the Dead Sea Basin to the south (55-62 mW m⁻²). The observed range can be explained by variation in the composition (heat production) of the upper crust, accompanied by more systematic spatial changes in its thickness. The new qs data then can be used, in conjunction with petrophysical data and information on the structure and composition of the lithosphere, to adjust a model of the pre-Oligocene thermal state of the crust in south-central Israel. The 2-D steady-state temperature model was calculated along an E-W traverse based on the DESIRE seismic profile (Mechie et al., 2009). The model comprises the entire lithosphere down to the lithosphere-asthenosphere boundary (LAB) involving the most recent knowledge of the lithosphere in pre-Oligocene time, i.e., prior to the onset of rifting and plume-related lithospheric thermal perturbations. The adjustment of modeled and measured qs allows conclusions about the pre-Oligocene LAB-depth. After the best fitting the most likely depth is 150 km which is consistent with estimations made in comparable regions of the Arabian Shield. It therefore comprises the first ever modelled pre-Oligocene LAB depth, and provides important clues on the thermal state of lithosphere before rifting. This, in turn, is vital for a better understanding of the (thermo)-dynamic processes associated with lithosphere extension and continental break-up.}, language = {en} } @phdthesis{RiveraVillarreyes2013, author = {Rivera Villarreyes, Carlos Andres}, title = {Cosmic-ray neutron sensing for soil moisture measurements in cropped fields}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69748}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {This cumulative dissertation explored the use of the detection of natural background of fast neutrons, the so-called cosmic-ray neutron sensing (CRS) approach to measure field-scale soil moisture in cropped fields. Primary cosmic rays penetrate the top atmosphere and interact with atmospheric particles. Such interaction results on a cascade of high-energy neutrons, which continue traveling through the atmospheric column. Finally, neutrons penetrate the soil surface and a second cascade is produced with the so-called secondary cosmic-ray neutrons (fast neutrons). Partly, fast neutrons are absorbed by hydrogen (soil moisture). Remaining neutrons scatter back to the atmosphere, where its flux is inversely correlated to the soil moisture content, therefore allowing a non-invasive indirect measurement of soil moisture. The CRS methodology is mainly evaluated based on a field study carried out on a farmland in Potsdam (Brandenburg, Germany) along three crop seasons with corn, sunflower and winter rye; a bare soil period; and two winter periods. Also, field monitoring was carried out in the Schaefertal catchment (Harz, Germany) for long-term testing of CRS against ancillary data. In the first experimental site, the CRS method was calibrated and validated using different approaches of soil moisture measurements. In a period with corn, soil moisture measurement at the local scale was performed at near-surface only, and in subsequent periods (sunflower and winter rye) sensors were placed in three depths (5 cm, 20 cm and 40 cm). The direct transfer of CRS calibration parameters between two vegetation periods led to a large overestimation of soil moisture by the CRS. Part of this soil moisture overestimation was attributed to an underestimation of the CRS observation depth during the corn period ( 5-10 cm), which was later recalculated to values between 20-40 cm in other crop periods (sunflower and winter rye). According to results from these monitoring periods with different crops, vegetation played an important role on the CRS measurements. Water contained also in crop biomass, above and below ground, produces important neutron moderation. This effect was accounted for by a simple model for neutron corrections due to vegetation. It followed crop development and reduced overall CRS soil moisture error for periods of sunflower and winter rye. In Potsdam farmland also inversely-estimated soil hydraulic parameters were determined at the field scale, using CRS soil moisture from the sunflower period. A modelling framework coupling HYDRUS-1D and PEST was applied. Subsequently, field-scale soil hydraulic properties were compared against local scale soil properties (modelling and measurements). Successful results were obtained here, despite large difference in support volume. Simple modelling framework emphasizes future research directions with CRS soil moisture to parameterize field scale models. In Schaefertal catchment, CRS measurements were verified using precipitation and evapotranspiration data. At the monthly resolution, CRS soil water storage was well correlated to these two weather variables. Also clearly, water balance could not be closed due to missing information from other compartments such as groundwater, catchment discharge, etc. In the catchment, the snow influence to natural neutrons was also evaluated. As also observed in Potsdam farmland, CRS signal was strongly influenced by snow fall and snow accumulation. A simple strategy to measure snow was presented for Schaefertal case. Concluding remarks of this dissertation showed that (a) the cosmic-ray neutron sensing (CRS) has a strong potential to provide feasible measurement of mean soil moisture at the field scale in cropped fields; (b) CRS soil moisture is strongly influenced by other environmental water pools such as vegetation and snow, therefore these should be considered in analysis; (c) CRS water storage can be used for soil hydrology modelling for determination of soil hydraulic parameters; and (d) CRS approach has strong potential for long term monitoring of soil moisture and for addressing studies of water balance.}, language = {en} } @phdthesis{Thomas2013, author = {Thomas, Bj{\"o}rn Daniel}, title = {Analysis and management of low flows in small catchments of Brandenburg, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69247}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Water management and environmental protection is vulnerable to extreme low flows during streamflow droughts. During the last decades, in most rivers of Central Europe summer runoff and low flows have decreased. Discharge projections agree that future decrease in runoff is likely for catchments in Brandenburg, Germany. Depending on the first-order controls on low flows, different adaption measures are expected to be appropriate. Small catchments were analyzed because they are expected to be more vulnerable to a changing climate than larger rivers. They are mainly headwater catchments with smaller ground water storage. Local characteristics are more important at this scale and can increase vulnerability. This thesis mutually evaluates potential adaption measures to sustain minimum runoff in small catchments of Brandenburg, Germany, and similarities of these catchments regarding low flows. The following guiding questions are addressed: (i) Which first-order controls on low flows and related time scales exist? (ii) Which are the differences between small catchments regarding low flow vulnerability? (iii) Which adaption measures to sustain minimum runoff in small catchments of Brandenburg are appropriate considering regional low flow patterns? Potential adaption measures to sustain minimum runoff during periods of low flows can be classified into three categories: (i) increase of groundwater recharge and subsequent baseflow by land use change, land management and artificial ground water recharge, (ii) increase of water storage with regulated outflow by reservoirs, lakes and wetland water management and (iii) regional low flow patterns have to be considered during planning of measures with multiple purposes (urban water management, waste water recycling and inter-basin water transfer). The question remained whether water management of areas with shallow groundwater tables can efficiently sustain minimum runoff. Exemplary, water management scenarios of a ditch irrigated area were evaluated using the model Hydrus-2D. Increasing antecedent water levels and stopping ditch irrigation during periods of low flows increased fluxes from the pasture to the stream, but storage was depleted faster during the summer months due to higher evapotranspiration. Fluxes from this approx. 1 km long pasture with an area of approx. 13 ha ranged from 0.3 to 0.7 l\s depending on scenario. This demonstrates that numerous of such small decentralized measures are necessary to sustain minimum runoff in meso-scale catchments. Differences in the low flow risk of catchments and meteorological low flow predictors were analyzed. A principal component analysis was applied on daily discharge of 37 catchments between 1991 and 2006. Flows decreased more in Southeast Brandenburg according to meteorological forcing. Low flow risk was highest in a region east of Berlin because of intersection of a more continental climate and the specific geohydrology. In these catchments, flows decreased faster during summer and the low flow period was prolonged. A non-linear support vector machine regression was applied to iteratively select meteorological predictors for annual 30-day minimum runoff in 16 catchments between 1965 and 2006. The potential evapotranspiration sum of the previous 48 months was the most important predictor (r²=0.28). The potential evapotranspiration of the previous 3 months and the precipitation of the previous 3 months and last year increased model performance (r²=0.49, including all four predictors). Model performance was higher for catchments with low yield and more damped runoff. In catchments with high low flow risk, explanatory power of long term potential evapotranspiration was high. Catchments with a high low flow risk as well as catchments with a considerable decrease in flows in southeast Brandenburg have the highest demand for adaption. Measures increasing groundwater recharge are to be preferred. Catchments with high low flow risk showed relatively deep and decreasing groundwater heads allowing increased groundwater recharge at recharge areas with higher altitude away from the streams. Low flows are expected to stay low or decrease even further because long term potential evapotranspiration was the most important low flow predictor and is projected to increase during climate change. Differences in low flow risk and runoff dynamics between catchments have to be considered for management and planning of measures which do not only have the task to sustain minimum runoff.}, language = {en} } @phdthesis{Macaulay2013, author = {Macaulay, Euan Angus}, title = {The orogenic evolution of the Central Kyrgyz Tien Shan}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68985}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Intra-continental mountain belts typically form as a result of tectonic forces associated with distant plate collisions. In general, each mountain belt has a distinctive morphology and orogenic evolution that is highly dependent on the unique distribution and geometries of inherited structures and other crustal weaknesses. In this thesis, I have investigated the complex and irregular Cenozoic orogenic evolution of the Central Kyrgyz Tien Shan in Central Asia, which is presently one of the most active intra-continental mountain belts in the world. This work involved combining a broad array of datasets, including thermochronologic, magnetostratigraphic, sediment provenance and stable isotope data, to identify and date various changes in tectonic deformation, climate and surface processes. Many of these changes are linked and can ultimately be related to regional-scale processes that altered the orogenic evolution of the Central Kyrgyz Tien Shan. The Central Kyrgyz Tien Shan contains a sub-parallel series of structures that were reactivated in the late Cenozoic in response to the tectonic forces associated with the distant India-Eurasia collision. Over time, slip on the various reactivated structures created the succession of mountain ranges and intermontane basins which characterises the modern morphology of the region. In this thesis, new quantitative constraints on the exhumation histories of several mountain ranges have been obtained by using low temperature thermochronological data from 95 samples (zircon (U-Th)/He, apatite fission track and (U-Th)/He). Time-temperature histories derived by modelling the thermochronologic data of individual samples identify at least two stages of Cenozoic cooling in most of the region's mountain ranges: (1) initially low cooling rates (<1°C/Myr) during the tectonic quiescent period and (2) increased cooling in the late Cenozoic, which occurred diachronously and with variable magnitude in different ranges. This second cooling stage is interpreted to represent increased erosion caused by active deformation, and in many of the sampled mountain ranges, provides the first available constraints on the timing of late Cenozoic deformation. New constraints on the timing of deformation have also been derived from the sedimentary record of intermontane basins. In the intermontane Issyk Kul basin, new magnetostratigraphic data from two sedimentary sections suggests that deposition of the first Cenozoic syn-tectonic sediments commenced at ~26 Ma. Zircon U-Pb provenance data, paleocurrent and conglomerate clast analysis reveals that these sediments were sourced from the Terskey Range to the south of the basin, suggesting that the onset of the late Cenozoic deformation occurred >26 Ma in that particular range. Elsewhere, growth strata relationships are used to identify syn-tecotnic deposition and constrain the timing of nearby deformation. Collectively, these new constraints obtained from thermochronologic and sedimentary data have allowed me to infer the spatiotemporal distribution of deformation in a transect through the Central Kyrgyz Tien Shan, and determine the order in which mountain ranges started deforming. These data suggest that deformation began in a few widely-spaced mountain ranges in the late Oligocene and early Miocene. Typically, these earlier mountain ranges are bounded on at least one side by a reactivated structure, which probably corresponds to the frictionally weakest and most suitably orientated inherited structures for accommodating the roughly north-south directed horizontal crustal shortening of the late Cenozoic. Moreover, tectonically-induced rock uplift in the Terskey Range, following the reactivation of the bounding structure before 26 Ma, likely caused significant surface uplift across the range, which in turn lead to enhanced orographic precipitation. These wetter conditions have been inferred from stable isotope data collected in the two magnetostratigraphically-dated sections in the Issyk Kul basin. Subsequently, in the late Miocene (~12‒5 Ma), more mountain ranges and inherited structures appear to have started actively deforming. Importantly, the onset of deformation at these locations in the late Miocene coincides with an increase in exhumation of ranges that had started deforming earlier in the late Oligocene‒early Miocene. Based on this observation, I have suggested that there must have been an overall increase in the rate of horizontal crustal shortening across the Central Kyrgyz Tien Shan, which likely relates to regional tectonic changes that affected much of Central Asia. Many of the mountain ranges that started deforming in the late Miocene were associated with out-of-sequence tectonic reactivation and initiation, which lead to the partitioning of larger intermontane basins. Moreover, within most of the intermontane basins in the Central Kyrgyz Tien Shan, this inferred late Miocene increase in horizontal crustal shortening occurs roughly at the same time as an increase in sedimentation rates and a significant change sediment composition. Therefore, I have suggested that the overall magnitude of deformational processes increased in the late Miocene, promoting more flexural subsidence in the intermontane basins of the Central Kyrgyz Tien Shan.}, language = {en} } @phdthesis{Schlolaut2013, author = {Schlolaut, Gordon}, title = {Varve and event layer chronology of Lake Suigetsu (Japan) back to 40 kyr BP and contribution to the international consensus atmospheric radiocarbon calibration curve}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69096}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The main intention of the PhD project was to create a varve chronology for the Suigetsu Varves 2006' (SG06) composite profile from Lake Suigetsu (Japan) by thin section microscopy. The chronology was not only to provide an age-scale for the various palaeo-environmental proxies analysed within the SG06 project, but also and foremost to contribute, in combination with the SG06 14C chronology, to the international atmospheric radiocarbon calibration curve (IntCal). The SG06 14C data are based on terrestrial leaf fossils and therefore record atmospheric 14C values directly, avoiding the corrections necessary for the reservoir ages of the marine datasets, which are currently used beyond the tree-ring limit in the IntCal09 dataset (Reimer et al., 2009). The SG06 project is a follow up of the SG93 project (Kitagawa \& van der Plicht, 2000), which aimed to produce an atmospheric calibration dataset, too, but suffered from incomplete core recovery and varve count uncertainties. For the SG06 project the complete Lake Suigetsu sediment sequence was recovered continuously, leaving the task to produce an improved varve count. Varve counting was carried out using a dual method approach utilizing thin section microscopy and micro X-Ray Fluorescence (µXRF). The latter was carried out by Dr. Michael Marshall in cooperation with the PhD candidate. The varve count covers 19 m of composite core, which corresponds to the time frame from ≈10 to ≈40 kyr BP. The count result showed that seasonal layers did not form in every year. Hence, the varve counts from either method were incomplete. This rather common problem in varve counting is usually solved by manual varve interpolation. But manual interpolation often suffers from subjectivity. Furthermore, sedimentation rate estimates (which are the basis for interpolation) are generally derived from neighbouring, well varved intervals. This assumes that the sedimentation rates in neighbouring intervals are identical to those in the incompletely varved section, which is not necessarily true. To overcome these problems a novel interpolation method was devised. It is computer based and automated (i.e. avoids subjectivity and ensures reproducibility) and derives the sedimentation rate estimate directly from the incompletely varved interval by statistically analysing distances between successive seasonal layers. Therefore, the interpolation approach is also suitable for sediments which do not contain well varved intervals. Another benefit of the novel method is that it provides objective interpolation error estimates. Interpolation results from the two counting methods were combined and the resulting chronology compared to the 14C chronology from Lake Suigetsu, calibrated with the tree-ring derived section of IntCal09 (which is considered accurate). The varve and 14C chronology showed a high degree of similarity, demonstrating that the novel interpolation method produces reliable results. In order to constrain the uncertainties of the varve chronology, especially the cumulative error estimates, U-Th dated speleothem data were used by linking the low frequency 14C signal of Lake Suigetsu and the speleothems, increasing the accuracy and precision of the Suigetsu calibration dataset. The resulting chronology also represents the age-scale for the various palaeo-environmental proxies analysed in the SG06 project. One proxy analysed within the PhD project was the distribution of event layers, which are often representatives of past floods or earthquakes. A detailed microfacies analysis revealed three different types of event layers, two of which are described here for the first time for the Suigetsu sediment. The types are: matrix supported layers produced as result of subaqueous slope failures, turbidites produced as result of landslides and turbidites produced as result of flood events. The former two are likely to have been triggered by earthquakes. The vast majority of event layers was related to floods (362 out of 369), which allowed the construction of a respective chronology for the last 40 kyr. Flood frequencies were highly variable, reaching their greatest values during the global sea level low-stand of the Glacial, their lowest values during Heinrich Event 1. Typhoons affecting the region represent the most likely control on the flood frequency, especially during the Glacial. However, also local, non-climatic controls are suggested by the data. In summary, the work presented here expands and revises knowledge on the Lake Suigetsu sediment and enabls the construction of a far more precise varve chronology. The 14C calibration dataset is the first such derived from lacustrine sediments to be included into the (next) IntCal dataset. References: Kitagawa \& van der Plicht, 2000, Radiocarbon, Vol 42(3), 370-381 Reimer et al., 2009, Radiocarbon, Vol 51(4), 1111-1150}, language = {en} } @phdthesis{BaumannWilke2013, author = {Baumann-Wilke, Maria}, title = {Combining body wave tomography, surface wave inversion, seismic interferometry and laboratory measurements to characterize the black shales on Bornholm at different scales}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69007}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Black shales are sedimentary rocks with a high content of organic carbon, which leads to a dark grayish to black color. Due to their potential to contain oil or gas, black shales are of great interest for the support of the worldwide energy supply. An integrated seismic investigation of the Lower Palaeozoic black shales was carried out at the Danish island Bornholm to locate the shallow-lying Alum Shale layer and its surrounding formations and to characterize its potential as a source rock. Therefore, two seismic experiments at a total of three crossing profiles were carried out in October 2010 and in June 2012 in the southern part of the island. Two different active measurements were conducted with either a weight drop source or a minivibrator. Additionally, the ambient noise field was recorded at the study location over a time interval of about one day, and also a laboratory analysis of borehole samples was carried out. The seismic profiles were positioned as close as possible to two scientific boreholes which were used for comparative purposes. The seismic field data was analyzed with traveltime tomography, surface wave inversion and seismic interferometry to obtain the P-wave and S-wave velocity models of the subsurface. The P-wave velocity models which were determined for all three profiles clearly locate the Alum Shale layer between the Komstad Limestone layer on top and the L{\ae}s{\aa} Sandstone Formation at the base of the models. The black shale layer has P-wave velocities around 3 km/s which are lower compared to the adjacent formations. Due to a very good agreement of the sonic log and the vertical velocity profiles of the two seismic lines, which are directly crossing the borehole where the sonic log was conducted, the reliability of the traveltime tomography is proven. A correlation of the seismic velocities with the content of organic carbon is an important task for the characterization of the reservoir properties of a black shale formation. It is not possible without calibration but in combination with a full 2D tomographic image of the subsurface it gives the subsurface distribution of the organic material. The S-wave model obtained with surface wave inversion of the vibroseis data of one of the profiles images the Alum Shale layer also very well with S-wave velocities around 2 km/s. Although individual 1D velocity models for each of the source positions were determined, the subsurface S-wave velocity distribution is very uniform with a good match between the single models. A really new approach described here is the application of seismic interferometry to a really small study area and a quite short time interval. Also new is the selective procedure of only using time windows with the best crosscorrelation signals to achieve the final interferograms. Due to the small scale of the interferometry even P-wave signals can be observed in the final crosscorrelations. In the laboratory measurements the seismic body waves were recorded for different pressure and temperature stages. Therefore, samples of different depths of the Alum Shale were available from one of the scientific boreholes at the study location. The measured velocities have a high variance with changing pressure or temperature. Recordings with wave propagation both parallel and perpendicular to the bedding of the samples reveal a great amount of anisotropy for the P-wave velocity, whereas the S-wave velocity is almost independent of the wave direction. The calculated velocity ratio is also highly anisotropic with very low values for the perpendicular samples and very high values for the parallel ones. Interestingly, the laboratory velocities of the perpendicular samples are comparable to the velocities of the field experiments indicating that the field measurements are sensitive to wave propagation in vertical direction. The velocity ratio is also calculated with the P-wave and S-wave velocity models of the field experiments. Again, the Alum Shale can be clearly separated from the adjacent formations because it shows overall very low vP/vS ratios around 1.4. The very low velocity ratio indicates the content of gas in the black shale formation. With the combination of all the different methods described here, a comprehensive interpretation of the seismic response of the black shale layer can be made and the hydrocarbon source rock potential can be estimated.}, language = {en} } @phdthesis{Bischoff2013, author = {Bischoff, Juliane}, title = {Microbial communities and their response to Pleistocene and Holocene climate variabilities in the Russian Arctic}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68895}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The Arctic is considered as a focal region in the ongoing climate change debate. The currently observed and predicted climate warming is particularly pronounced in the high northern latitudes. Rising temperatures in the Arctic cause progressive deepening and duration of permafrost thawing during the arctic summer, creating an 'active layer' with high bioavailability of nutrients and labile carbon for microbial consumption. The microbial mineralization of permafrost carbon creates large amounts of greenhouse gases, including carbon dioxide and methane, which can be released to the atmosphere, creating a positive feedback to global warming. However, to date, the microbial communities that drive the overall carbon cycle and specifically methane production in the Arctic are poorly constrained. To assess how these microbial communities will respond to the predicted climate changes, such as an increase in atmospheric and soil temperatures causing increased bioavailability of organic carbon, it is necessary to investigate the current status of this environment, but also how these microbial communities reacted to climate changes in the past. This PhD thesis investigated three records from two different study sites in the Russian Arctic, including permafrost, lake shore and lake deposits from Siberia and Chukotka. A combined stratigraphic approach of microbial and molecular organic geochemical techniques were used to identify and quantify characteristic microbial gene and lipid biomarkers. Based on this data it was possible to characterize and identify the climate response of microbial communities involved in past carbon cycling during the Middle Pleistocene and the Late Pleistocene to Holocene. It is shown that previous warmer periods were associated with an expansion of bacterial and archaeal communities throughout the Russian Arctic, similar to present day conditions. Different from this situation, past glacial and stadial periods experienced a substantial decrease in the abundance of Bacteria and Archaea. This trend can also be confirmed for the community of methanogenic archaea that were highly abundant and diverse during warm and particularly wet conditions. For the terrestrial permafrost, a direct effect of the temperature on the microbial communities is likely. In contrast, it is suggested that the temperature rise in scope of the glacial-interglacial climate variations led to an increase of the primary production in the Arctic lake setting, as can be seen in the corresponding biogenic silica distribution. The availability of this algae-derived carbon is suggested to be a driver for the observed pattern in the microbial abundance. This work demonstrates the effect of climate changes on the community composition of methanogenic archae. Methanosarcina-related species were abundant throughout the Russian Arctic and were able to adapt to changing environmental conditions. In contrast, members of Methanocellales and Methanomicrobiales were not able to adapt to past climate changes. This PhD thesis provides first evidence that past climatic warming led to an increased abundance of microbial communities in the Arctic, closely linked to the cycling of carbon and methane production. With the predicted climate warming, it may, therefore, be anticipated that extensive amounts of microbial communities will develop. Increasing temperatures in the Arctic will affect the temperature sensitive parts of the current microbiological communities, possibly leading to a suppression of cold adapted species and the prevalence of methanogenic archaea that tolerate or adapt to increasing temperatures. These changes in the composition of methanogenic archaea will likely increase the methane production potential of high latitude terrestrial regions, changing the Arctic from a carbon sink to a source.}, language = {en} } @phdthesis{Abdelfadil2013, author = {Abdelfadil, Khaled Mohamed}, title = {Geochemistry of Variscan lamprophyre magmatism in the Saxo-Thuringian Zone}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68854}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Lamprophyres are mantle-derived magmatic rocks, commonly occurring as dikes. They are readily identified from their field setting, petrography, chemical and mineralogical composition. These rocks not only provide important information on melting processes in the mantle, but also on geodynamic processes modifying the mantle. There are numerous occurrences of lamprophyres in the Saxo-Thuringian Zone of Variscan Central Europe, which are useful to track the variable effects of the Variscan orogeny on local mantle evolution. This work presents and evaluates the mineralogical, geochemical, and Sr-Nd-Pb isotopic data of late-Variscan calc-alkaline lamprophyres, post-Variscan ultramafic lamprophyres, of alkaline basalt from Lusatia, and, for comparison, of pre-Variscan gabbros. In addition, lithium isotopic signatures combined with Sr-Nd-Pb isotopic data of late-Variscan calc-alkaline lamprophyres from three different Variscan Domains (i.e., Erzgebirge, Lusatia, and Sudetes) are used to assess compositional changes of the mantle during Variscan orogeny.}, language = {de} } @phdthesis{Sauer2013, author = {Sauer, Patrick}, title = {Liberation of low molecular weight organic acids from sedimentary organic matter and their role on microbial activity}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68830}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Low molecular weight organic acids (LMWOAs) are important nutrients for microbes. However, most LMWOAs do not exist freely in the environment but are bound to macromolecular organic matter, e.g. kerogen, lignite and coal. During burial and geological maturation of sedimentary macromolecular organic matter biological and abiological processes promote the liberation of LMWOAs into the surrounding sediment. Through this process, microbes in sedimentary subsurface environments are supplied with essential nutrients. To estimate the feedstock potential of buried macromolecular organic matter to many environments it is important to determine the amount of LMWOAs that are bound to such a matrix. However, high-pressure and high temperature are a key feature of deep subsurface environments, and these physical parameters have a profound influence on chemical reaction kinetics. Therefore it is essential for the estimation of the feedstock potential to generate high-pressure and high temperature for the liberation of LMWOAs to recreate true in-situ conditions. This work presents a newly developed, inexpensive incubation system for biological and geological samples. It allows the application of high-pressure and high temperature as well as a subsampling of the liquid phase without loss of pressure, thereby not disturbing the on-going processes. When simulating the liberation of LMWOAs from sedimentary organic matter, the newly developed incubation system produces more realistic results than other extraction systems like Soxhlet. The extraction products remain in the extraction medium throughout the extraction, influencing the chemical conditions of the extraction medium. Sub-bituminous coal samples from New Zealand as well as lignite samples from Germany were extracted at elevated temperature (90˚C) and pressure (5 MPa). The main LMWOAs released from these low rank coals were formate, acetate and oxalate. Extraction efficiency was increased by two to four times for formate, acetate and oxalate in comparison to existing extraction methods without pressurisation and with demineralised water. This shows the importance of pressure for the simulation of true in-situ conditions and suggests that the amount of bioavailable LMWOAs is higher than previously thought. With the increase in carbon capture and storage (CCS) and the enhanced recovery of oil and gas (EOR/EGR), more and more CO2 becomes injected into the underground. However, the effects of elevated concentrations of carbon dioxide on sedimentary organic matter are rarely investigated. As the incuabtion system allows the manipulation of the composition and partial pressure of dissolved gasses, the effect of highly gas-enriched (CO2, CO2/SO2, CO2/NO2; to simulate flue gas conditions) waters on the extraction yield of LMWOAs from macromolecular organic matter was evaluated. For sub-bituminous coal the concentrations of all LMWAOs decreased upon the addition of gas, irrespective of its composition, whereas for lignite formate always and acetate mostly increased, while oxalate decreased. This suggests an positive effect on the nutrient supply for the subsurface microbiota of lignite layers, as formate and acetate are the most common LMWOAs used for microbial metabolism. In terrestrial mud volcanoes (TMVs), sedimentary material is rapidly ascending from great depth to the surface. Therefore LMWOAs that were produced from buried macromolecular organic matter at depth are also brought up to the surface, and fuel heterotrophic microbial ecosystems at the surface. TMVs represent geochemically and microbiologically diverse habitats, which are supplied with organic substrates and electron acceptors from deep-seated hydrocarbon-generating systems and intersected shallow aquifers, respectively. The main electron donor in TMVs in Azerbaijan is sulphate, and microbial sulphate reduction leads to the production of a wide range of reduced sulphur species that are key players in several biological processes. In our study we estimated the effect of LMWOAs on the sulphur metabolising activity of microorganims in TMVs from Azerbaijan. The addition of a mixture of volatile fatty acids containing acetate and other LMWOAs showed significant positive response to the sulphate reduction rate (SRR) of samples of several mud volcanoes. Further investigations on the temperature dependency of the SRR and the characterisation of thermophilic sulphate-reducing bacteria (SRB) showed a connection between the deep hot subsurface and the surface.}, language = {de} } @phdthesis{Bajerski2013, author = {Bajerski, Felizitas}, title = {Bacterial communities in glacier forefields of the Larsemann Hills, East Antarctica : structure, development \& adaptation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67424}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Antarctic glacier forfields are extreme environments and pioneer sites for ecological succession. The Antarctic continent shows microbial community development as a natural laboratory because of its special environment, geographic isolation and little anthropogenic influence. Increasing temperatures due to global warming lead to enhanced deglaciation processes in cold-affected habitats and new terrain is becoming exposed to soil formation and accessible for microbial colonisation. This study aims to understand the structure and development of glacier forefield bacterial communities, especially how soil parameters impact the microorganisms and how those are adapted to the extreme conditions of the habitat. To this effect, a combination of cultivation experiments, molecular, geophysical and geochemical analysis was applied to examine two glacier forfields of the Larsemann Hills, East Antarctica. Culture-independent molecular tools such as terminal restriction length polymorphism (T-RFLP), clone libraries and quantitative real-time PCR (qPCR) were used to determine bacterial diversity and distribution. Cultivation of yet unknown species was carried out to get insights in the physiology and adaptation of the microorganisms. Adaptation strategies of the microorganisms were studied by determining changes of the cell membrane phospholipid fatty acid (PLFA) inventory of an isolated bacterium in response to temperature and pH fluctuations and by measuring enzyme activity at low temperature in environmental soil samples. The two studied glacier forefields are extreme habitats characterised by low temperatures, low water availability and small oligotrophic nutrient pools and represent sites of different bacterial succession in relation to soil parameters. The investigated sites showed microbial succession at an early step of soil formation near the ice tongue in comparison to closely located but rather older and more developed soil from the forefield. At the early step the succession is influenced by a deglaciation-dependent areal shift of soil parameters followed by a variable and prevalently depth-related distribution of the soil parameters that is driven by the extreme Antarctic conditions. The dominant taxa in the glacier forefields are Actinobacteria, Acidobacteria, Proteobacteria, Bacteroidetes, Cyanobacteria and Chloroflexi. The connection of soil characteristics with bacterial community structure showed that soil parameter and soil formation along the glacier forefield influence the distribution of certain phyla. In the early step of succession the relative undifferentiated bacterial diversity reflects the undifferentiated soil development and has a high potential to shift according to past and present environmental conditions. With progressing development environmental constraints such as water or carbon limitation have a greater influence. Adapting the culturing conditions to the cold and oligotrophic environment, the number of culturable heterotrophic bacteria reached up to 108 colony forming units per gram soil and 148 isolates were obtained. Two new psychrotolerant bacteria, Herbaspirillum psychrotolerans PB1T and Chryseobacterium frigidisoli PB4T, were characterised in detail and described as novel species in the family of Oxalobacteraceae and Flavobacteriaceae, respectively. The isolates are able to grow at low temperatures tolerating temperature fluctuations and they are not specialised to a certain substrate, therefore they are well-adapted to the cold and oligotrophic environment. The adaptation strategies of the microorganisms were analysed in environmental samples and cultures focussing on extracellular enzyme activity at low temperature and PLFA analyses. Extracellular phosphatases (pH 11 and pH 6.5), β-glucosidase, invertase and urease activity were detected in the glacier forefield soils at low temperature (14°C) catalysing the conversion of various compounds providing necessary substrates and may further play a role in the soil formation and total carbon turnover of the habitat. The PLFA analysis of the newly isolated species C. frigidisoli showed that the cold-adapted strain develops different strategies to maintain the cell membrane function under changing environmental conditions by altering the PLFA inventory at different temperatures and pH values. A newly discovered fatty acid, which was not found in any other microorganism so far, significantly increased at decreasing temperature and low pH and thus plays an important role in the adaption of C. frigidisoli. This work gives insights into the diversity, distribution and adaptation mechanisms of microbial communities in oligotrophic cold-affected soils and shows that Antarctic glacier forefields are suitable model systems to study bacterial colonisation in connection to soil formation.}, language = {en} } @phdthesis{Fuchs2013, author = {Fuchs, Sven}, title = {Well-log based determination of rock thermal conductivity in the North German Basin}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67801}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In sedimentary basins, rock thermal conductivity can vary both laterally and vertically, thus altering the basin's thermal structure locally and regionally. Knowledge of the thermal conductivity of geological formations and its spatial variations is essential, not only for quantifying basin evolution and hydrocarbon maturation processes, but also for understanding geothermal conditions in a geological setting. In conjunction with the temperature gradient, thermal conductivity represents the basic input parameter for the determination of the heat-flow density; which, in turn, is applied as a major input parameter in thermal modeling at different scales. Drill-core samples, which are necessary to determine thermal properties by laboratory measurements, are rarely available and often limited to previously explored reservoir formations. Thus, thermal conductivities of Mesozoic rocks in the North German Basin (NGB) are largely unknown. In contrast, geophysical borehole measurements are often available for the entire drilled sequence. Therefore, prediction equations to determine thermal conductivity based on well-log data are desirable. In this study rock thermal conductivity was investigated on different scales by (1) providing thermal-conductivity measurements on Mesozoic rocks, (2) evaluating and improving commonly applied mixing models which were used to estimate matrix and pore-filled rock thermal conductivities, and (3) developing new well-log based equations to predict thermal conductivity in boreholes without core control. Laboratory measurements are performed on sedimentary rock of major geothermal reservoirs in the Northeast German Basin (NEGB) (Aalenian, Rhaethian-Liassic, Stuttgart Fm., and Middle Buntsandstein). Samples are obtained from eight deep geothermal wells that approach depths of up to 2,500 m. Bulk thermal conductivities of Mesozoic sandstones range between 2.1 and 3.9 W/(m∙K), while matrix thermal conductivity ranges between 3.4 and 7.4 W/(m∙K). Local heat flow for the Stralsund location averages 76 mW/m², which is in good agreement to values reported previously for the NEGB. For the first time, in-situ bulk thermal conductivity is indirectly calculated for entire borehole profiles in the NEGB using the determined surface heat flow and measured temperature data. Average bulk thermal conductivity, derived for geological formations within the Mesozoic section, ranges between 1.5 and 3.1 W/(m∙K). The measurement of both dry- and water-saturated thermal conductivities allow further evaluation of different two-component mixing models which are often applied in geothermal calculations (e.g., arithmetic mean, geometric mean, harmonic mean, Hashin-Shtrikman mean, and effective-medium theory mean). It is found that the geometric-mean model shows the best correlation between calculated and measured bulk thermal conductivity. However, by applying new model-dependent correction, equations the quality of fit could be significantly improved and the error diffusion of each model reduced. The 'corrected' geometric mean provides the most satisfying results and constitutes a universally applicable model for sedimentary rocks. Furthermore, lithotype-specific and model-independent conversion equations are developed permitting a calculation of water-saturated thermal conductivity from dry-measured thermal conductivity and porosity within an error range of 5 to 10\%. The limited availability of core samples and the expensive core-based laboratory measurements make it worthwhile to use petrophysical well logs to determine thermal conductivity for sedimentary rocks. The approach followed in this study is based on the detailed analyses of the relationships between thermal conductivity of rock-forming minerals, which are most abundant in sedimentary rocks, and the properties measured by standard logging tools. By using multivariate statistics separately for clastic, carbonate and evaporite rocks, the findings from these analyses allow the development of prediction equations from large artificial data sets that predict matrix thermal conductivity within an error of 4 to 11\%. These equations are validated successfully on a comprehensive subsurface data set from the NGB. In comparison to the application of earlier published approaches formation-dependent developed for certain areas, the new developed equations show a significant error reduction of up to 50\%. These results are used to infer rock thermal conductivity for entire borehole profiles. By inversion of corrected in-situ thermal-conductivity profiles, temperature profiles are calculated and compared to measured high-precision temperature logs. The resulting uncertainty in temperature prediction averages < 5\%, which reveals the excellent temperature prediction capabilities using the presented approach. In conclusion, data and methods are provided to achieve a much more detailed parameterization of thermal models.}, language = {en} } @phdthesis{Adhikari2013, author = {Adhikari, Rishi Ram}, title = {Quantification of total microbial biomass and metabolic activity in subsurface sediments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67773}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Metabolically active microbial communities are present in a wide range of subsurface environments. Techniques like enumeration of microbial cells, activity measurements with radiotracer assays and the analysis of porewater constituents are currently being used to explore the subsurface biosphere, alongside with molecular biological analyses. However, many of these techniques reach their detection limits due to low microbial activity and abundance. Direct measurements of microbial turnover not just face issues of insufficient sensitivity, they only provide information about a single specific process but in sediments many different process can occur simultaneously. Therefore, the development of a new technique to measure total microbial activity would be a major improvement. A new tritium-based hydrogenase-enzyme assay appeared to be a promising tool to quantify total living biomass, even in low activity subsurface environments. In this PhD project total microbial biomass and microbial activity was quantified in different subsurface sediments using established techniques (cell enumeration and pore water geochemistry) as well as a new tritium-based hydrogenase enzyme assay. By using a large database of our own cell enumeration data from equatorial Pacific and north Pacific sediments and published data it was shown that the global geographic distribution of subseafloor sedimentary microbes varies between sites by 5 to 6 orders of magnitude and correlates with the sedimentation rate and distance from land. Based on these correlations, global subseafloor biomass was estimated to be 4.1 petagram-C and ~0.6 \% of Earth's total living biomass, which is significantly lower than previous estimates. Despite the massive reduction in biomass the subseafloor biosphere is still an important player in global biogeochemical cycles. To understand the relationship between microbial activity, abundance and organic matter flux into the sediment an expedition to the equatorial Pacific upwelling area and the north Pacific Gyre was carried out. Oxygen respiration rates in subseafloor sediments from the north Pacific Gyre, which are deposited at sedimentation rates of 1 mm per 1000 years, showed that microbial communities could survive for millions of years without fresh supply of organic carbon. Contrary to the north Pacific Gyre oxygen was completely depleted within the upper few millimeters to centimeters in sediments of the equatorial upwelling region due to a higher supply of organic matter and higher metabolic activity. So occurrence and variability of electron acceptors over depth and sites make the subsurface a complex environment for the quantification of total microbial activity. Recent studies showed that electron acceptor processes, which were previously thought to thermodynamically exclude each other can occur simultaneously. So in many cases a simple measure of the total microbial activity would be a better and more robust solution than assays for several specific processes, for example sulfate reduction rates or methanogenesis. Enzyme or molecular assays provide a more general approach as they target key metabolic compounds. Since hydrogenase enzymes are ubiquitous in microbes, the recently developed tritium-based hydrogenase radiotracer assay is applied to quantify hydrogenase enzyme activity as a parameter of total living cell activity. Hydrogenase enzyme activity was measured in sediments from different locations (Lake Van, Barents Sea, Equatorial Pacific and Gulf of Mexico). In sediment samples that contained nitrate, we found the lowest cell specific enzyme activity around 10^(-5) nmol H_(2) cell^(-1) d^(-1). With decreasing energy yield of the electron acceptor used, cell-specific hydrogenase activity increased and maximum values of up to 1 nmol H_(2) cell^(-1) d^(-1) were found in samples with methane concentrations of >10 ppm. Although hydrogenase activity cannot be converted directly into a turnover rate of a specific process, cell-specific activity factors can be used to identify specific metabolism and to quantify the metabolically active microbial population. In another study on sediments from the Nankai Trough microbial abundance and hydrogenase activity data show that both the habitat and the activity of subseafloor sedimentary microbial communities have been impacted by seismic activities. An increase in hydrogenase activity near the fault zone revealed that the microbial community was supplied with hydrogen as an energy source and that the microbes were specialized to hydrogen metabolism.}, language = {en} } @phdthesis{RudolphMohr2013, author = {Rudolph-Mohr, Nicole}, title = {A novel non-invasive optical method for quantitative visualization of pH and oxygen dynamics in soils}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66993}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In soils and sediments there is a strong coupling between local biogeochemical processes and the distribution of water, electron acceptors, acids and nutrients. Both sides are closely related and affect each other from small scale to larger scales. Soil structures such as aggregates, roots, layers or macropores enhance the patchiness of these distributions. At the same time it is difficult to access the spatial distribution and temporal dynamics of these parameter. Noninvasive imaging techniques with high spatial and temporal resolution overcome these limitations. And new non-invasive techniques are needed to study the dynamic interaction of plant roots with the surrounding soil, but also the complex physical and chemical processes in structured soils. In this study we developed an efficient non-destructive in-situ method to determine biogeochemical parameters relevant to plant roots growing in soil. This is a quantitative fluorescence imaging method suitable for visualizing the spatial and temporal pH changes around roots. We adapted the fluorescence imaging set-up and coupled it with neutron radiography to study simultaneously root growth, oxygen depletion by respiration activity and root water uptake. The combined set up was subsequently applied to a structured soil system to map the patchy structure of oxic and anoxic zones induced by a chemical oxygen consumption reaction for spatially varying water contents. Moreover, results from a similar fluorescence imaging technique for nitrate detection were complemented by a numerical modeling study where we used imaging data, aiming to simulate biodegradation under anaerobic, nitrate reducing conditions.}, language = {en} } @phdthesis{Hassler2013, author = {Haßler, Sibylle Kathrin}, title = {Saturated hydraulic conductivity in the humid tropics : sources of variability, implications for monitoring and effects on near-surface hydrological flow paths}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66864}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Large areas in the humid tropics are currently undergoing land-use change. The decrease of tropical rainforest, which is felled for land clearing and timber production, is countered by increasing areas of tree plantations and secondary forests. These changes are known to affect the regional water cycle as a result of plant-specific water demand and by influencing key soil properties which determine hydrological flow paths. One of these key properties sensitive to land-use change is the saturated hydraulic conductivity (Ks) as it governs vertical percolation of water within the soil profile. Low values of Ks in a certain soil depth can form an impeding layer and lead to perched water tables and the development of predominantly lateral flow paths such as overland flow. These processes can induce nutrient redistribution, erosion and soil degradation and thus affect ecosystem services and human livelihoods. Due to its sensitivity to land-use change, Ks is commonly used to assess the associated changes in hydrological flow paths. The objective of this dissertation was to assess the effect of land-use change on hydrological flow paths by analysing Ks as indicator variable. Sources of Ks variability, their implications for Ks monitoring and the relationship between Ks and near-surface hydrological flow paths in the context of land-use change were studied. The research area was located in central Panama, a country widely experiencing the abovementioned changes in land use. Ks is dependent on both static, soil-inherent properties such as particle size and clay mineralogy and dynamic, land use-dependent properties such as organic carbon content. By conducting a pair of studies with one of these influences held constant in each, the importance of static and dynamic properties for Ks was assessed. Applying a space-for-time approach to sample Ks under secondary forests of different age classes on comparable soils, a recovery of Ks from the former pasture use was shown to require more than eight years. The process was limited to the 0-6 cm sampling depth and showed large variability among replicates. A wavelet analysis of a Ks transect crossing different soil map units under comparable land cover, old-growth tropical rainforest, showed large small-scale variability, which was attributed to biotic influences, as well as a possible but non-conclusive influence of soil types. The two results highlight the importance of dynamic, land use-dependent influences on Ks. Monitoring studies can help to quantify land use-induced change of Ks, but there is a variety of sampling designs which differ in efficiency of estimating mean Ks. A comparative study of four designs and their suitability for Ks monitoring is used to give recommendations about designing a Ks monitoring scheme. Quantifying changes in spatial means of Ks for small catchments with a rotational stratified sampling design did not prove to be more efficient than Simple Random Sampling. The lack of large-scale spatial structure prevented benefits of stratification, and large small-scale variability resulting from local biotic processes and artificial effects of destructive sampling caused a lack of temporal consistency in the re-sampling of locations, which is part of the rotational design. The relationship between Ks and near-surface hydrological flow paths is of critical importance when assessing the consequences of land-use change in the humid tropics. The last part of this dissertation aimed at disclosing spatial relationships between Ks and overland flow as influenced by different land cover types. The effects of Ks on overland-flow generation were spatially variable, different between planar plots and incised flowlines and strongly influenced by land-cover characteristics. A simple comparison of Ks values and rainfall intensities was insufficient to describe the observed pattern of overland flow. Likewise, event flow in the stream was apparently not directly related to overland flow response patterns within the catchments. The study emphasises the importance of combining pedological, hydrological, meteorological and botanical measurements to comprehensively understand the land use-driven change in hydrological flow paths. In summary, Ks proved to be a suitable parameter for assessing the influence of land-use change on soils and hydrological processes. The results illustrated the importance of land cover and spatial variability of Ks for decisions on sampling designs and for interpreting overland-flow generation. As relationships between Ks and overland flow were shown to be complex and dependent on land cover, an interdisciplinary approach is required to comprehensively understand the effects of land-use change on soils and near-surface hydrological flow paths in the humid tropics.}, language = {en} }