@misc{KellermannBubeckKundelaetal.2017,
  author    = {Kellermann, Patric and Bubeck, Philip and Kundela, G{\"u}nther and Dosio, Alessandro and Thieken, Annegret},
  title     = {Frequency analysis of critical meteorological conditions in a changing climate},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400505},
  pages     = {19},
  year      = {2017},
  abstract  = {Meteorological extreme events have great potential for damaging railway infrastructure and posing risks to the safety of train passengers. In the future, climate change will presumably have serious implications on meteorological hazards in the Alpine region. Hence, attaining insights on future frequencies of meteorological extremes with relevance for the railway operation in Austria is required in the context of a comprehensive and sustainable natural hazard management plan of the railway operator. In this study, possible impacts of climate change on the frequencies of so-called critical meteorological conditions (CMCs) between the periods 1961-1990 and 2011-2040 are analyzed. Thresholds for such CMCs have been defined by the railway operator and used in its weather monitoring and early warning system. First, the seasonal climate change signals for air temperature and precipitation in Austria are described on the basis of an ensemble of high-resolution Regional Climate Model (RCM) simulations for Europe. Subsequently, the RCM-ensemble was used to investigate changes in the frequency of CMCs. Finally, the sensitivity of results is analyzed with varying threshold values for the CMCs. Results give robust indications for an all-season air temperature rise, but show no clear tendency in average precipitation. The frequency analyses reveal an increase in intense rainfall events and heat waves, whereas heavy snowfall and cold days are likely to decrease. Furthermore, results indicate that frequencies of CMCs are rather sensitive to changes of thresholds. It thus emphasizes the importance to carefully define, validate, andif neededto adapt the thresholds that are used in the weather monitoring and warning system of the railway operator. For this, continuous and standardized documentation of damaging events and near-misses is a pre-requisite.},
  language  = {en}
}
@misc{FluschnikKriewaldRosetal.2017,
  author    = {Fluschnik, Till and Kriewald, Steffen and Ros, Anselmo Garc{\´i}a Cant{\´u} and Zhou, Bin and Reusser, Dominik Edwin and Kropp, J{\"u}rgen and Rybski, Diego},
  title     = {The size distribution, scaling properties and spatial organization of urban clusters},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400486},
  pages     = {14},
  year      = {2017},
  abstract  = {Human development has far-reaching impacts on the surface of the globe. The transformation of natural land cover occurs in different forms, and urban growth is one of the most eminent transformative processes. We analyze global land cover data and extract cities as defined by maximally connected urban clusters. The analysis of the city size distribution for all cities on the globe confirms Zipf's law. Moreover, by investigating the percolation properties of the clustering of urban areas we assess the closeness to criticality for various countries. At the critical thresholds, the urban land cover of the countries undergoes a transition from separated clusters to a gigantic component on the country scale. We study the Zipf-exponents as a function of the closeness to percolation and find a systematic dependence, which could be the reason for deviating exponents reported in the literature. Moreover, we investigate the average size of the clusters as a function of the proximity to percolation and find country specific behavior. By relating the standard deviation and the average of cluster sizes—analogous to Taylor's law—we suggest an alternative way to identify the percolation transition. We calculate spatial correlations of the urban land cover and find long-range correlations. Finally, by relating the areas of cities with population figures we address the global aspect of the allometry of cities, finding an exponent δ ≈ 0.85, i.e., large cities have lower densities.},
  language  = {en}
}
@misc{RoezerMuellerBubecketal.2017,
  author    = {R{\"o}zer, Viktor and M{\"u}ller, Meike and Bubeck, Philip and Kienzler, Sarah and Thieken, Annegret and Pech, Ina and Schr{\"o}ter, Kai and Buchholz, Oliver and Kreibich, Heidi},
  title     = {Coping with pluvial floods by private households},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400465},
  pages     = {24},
  year      = {2017},
  abstract  = {Pluvial floods have caused severe damage to urban areas in recent years. With a projected increase in extreme precipitation as well as an ongoing urbanization, pluvial flood damage is expected to increase in the future. Therefore, further insights, especially on the adverse consequences of pluvial floods and their mitigation, are needed. To gain more knowledge, empirical damage data from three different pluvial flood events in Germany were collected through computer-aided telephone interviews. Pluvial flood awareness as well as flood experience were found to be low before the respective flood events. The level of private precaution increased considerably after all events, but is mainly focused on measures that are easy to implement. Lower inundation depths, smaller potential losses as compared with fluvial floods, as well as the fact that pluvial flooding may occur everywhere, are expected to cause a shift in damage mitigation from precaution to emergency response. However, an effective implementation of emergency measures was constrained by a low dissemination of early warnings in the study areas. Further improvements of early warning systems including dissemination as well as a rise in pluvial flood preparedness are important to reduce future pluvial flood damage.},
  language  = {en}
}
@misc{AroduduHelmingWiggeringetal.2017,
  author    = {Arodudu, Oludunsin Tunrayo and Helming, Katharina and Wiggering, Hubert and Voinov, Alexey},
  title     = {Bioenergy from low-intensity agricultural systems},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400403},
  pages     = {18},
  year      = {2017},
  abstract  = {In light of possible future restrictions on the use of fossil fuel, due to climate change obligations and continuous depletion of global fossil fuel reserves, the search for alternative renewable energy sources is expected to be an issue of great concern for policy stakeholders. This study assessed the feasibility of bioenergy production under relatively low-intensity conservative, eco-agricultural settings (as opposed to those produced under high-intensity, fossil fuel based industrialized agriculture). Estimates of the net energy gain (NEG) and the energy return on energy invested (EROEI) obtained from a life cycle inventory of the energy inputs and outputs involved reveal that the energy efficiency of bioenergy produced in low-intensity eco-agricultural systems could be as much as much as 448.5-488.3 GJ·ha-1 of NEG and an EROEI of 5.4-5.9 for maize ethanol production systems, and as much as 155.0-283.9 GJ·ha-1 of NEG and an EROEI of 14.7-22.4 for maize biogas production systems. This is substantially higher than for industrialized agriculture with a NEG of 2.8-52.5 GJ·ha-1 and an EROEI of 1.2-1.7 for maize ethanol production systems, as well as a NEG of 59.3-188.7 GJ·ha-1 and an EROEI of 2.2-10.2 for maize biogas production systems. Bioenergy produced in low-intensity eco-agricultural systems could therefore be an important source of energy with immense net benefits for local and regional end-users, provided a more efficient use of the co-products is ensured.},
  language  = {en}
}
@misc{BoescheRogassLubitzetal.2017,
  author    = {B{\"o}sche, Nina Kristine and Rogass, Christian and Lubitz, Christin and Brell, Maximilian and Herrmann, Sabrina and Mielke, Christian and Tonn, Sabine and Appelt, Oona and Altenberger, Uwe and Kaufmann, Hermann},
  title     = {Hyperspectral REE (Rare Earth Element) mapping of outcrops},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400171},
  pages     = {27},
  year      = {2017},
  abstract  = {In this study, an in situ application for identifying neodymium (Nd) enriched surface materials that uses multitemporal hyperspectral images is presented (HySpex sensor). Because of the narrow shape and shallow absorption depth of the neodymium absorption feature, a method was developed for enhancing and extracting the necessary information for neodymium from image spectra, even under illumination conditions that are not optimal. For this purpose, the two following approaches were developed: (1) reducing noise and analyzing changing illumination conditions by averaging multitemporal image scenes and (2) enhancing the depth of the desired absorption band by deconvolving every image spectrum with a Gaussian curve while the rest of the spectrum remains unchanged (Richardson-Lucy deconvolution). To evaluate these findings, nine field samples from the Fen complex in Norway were analyzed using handheld X-ray fluorescence devices and by conducting detailed laboratory-based geochemical rare earth element determinations. The result is a qualitative outcrop map that highlights zones that are enriched in neodymium. To reduce the influences of non-optimal illumination, particularly at the studied site, a minimum of seven single acquisitions is required. Sharpening the neodymium absorption band allows for robust mapping, even at the outer zones of enrichment. From the geochemical investigations, we found that iron oxides decrease the applicability of the method. However, iron-related absorption bands can be used as secondary indicators for sulfidic ore zones that are mainly enriched with rare earth elements. In summary, we found that hyperspectral spectroscopy is a noninvasive, fast and cost-saving method for determining neodymium at outcrop surfaces},
  language  = {en}
}
@misc{MalinowskiGroomSchwanghartetal.2017,
  author    = {Malinowski, Radosław and Groom, Geoff and Schwanghart, Wolfgang and Heckrath, Goswin},
  title     = {Detection and delineation of localized flooding from WorldView-2 multispectral data},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400149},
  pages     = {23},
  year      = {2017},
  abstract  = {Remote sensing technology serves as a powerful tool for analyzing geospatial characteristics of flood inundation events at various scales. However, the performance of remote sensing methods depends heavily on the flood characteristics and landscape settings. Difficulties might be encountered in mapping the extent of localized flooding with shallow water on riverine floodplain areas, where patches of herbaceous vegetation are interspersed with open water surfaces. To address the difficulties in mapping inundation on areas with complex water and vegetation compositions, a high spatial resolution dataset has to be used to reduce the problem of mixed pixels. The main objective of our study was to investigate the possibilities of using a single date WorldView-2 image of very high spatial resolution and supporting data to analyze spatial patterns of localized flooding on a riverine floodplain. We used a decision tree algorithm with various combinations of input variables including spectral bands of the WorldView-2 image, selected spectral indices dedicated to mapping water surfaces and vegetation, and topographic data. The overall accuracies of the twelve flood extent maps derived with the decision tree method and performed on both pixels and image objects ranged between 77\% and 95\%. The highest mapping overall accuracy was achieved with a method that utilized all available input data and the object-based image analysis. Our study demonstrates the possibility of using single date WorldView-2 data for analyzing flooding events at high spatial detail despite the absence of spectral bands from the short-waveform region that are frequently used in water related studies. Our study also highlights the importance of topographic data in inundation analyses. The greatest difficulties were met in mapping water surfaces under dense canopy herbaceous vegetation, due to limited water surface exposure and the dominance of vegetation reflectance.},
  language  = {en}
}
@misc{AichLierschVetteretal.2017,
  author    = {Aich, Valentin and Liersch, Stefan and Vetter, Tobias and Andersson, Jafet C. M. and M{\"u}ller, Eva Nora and Hattermann, Fred},
  title     = {Climate or land use?},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400115},
  pages     = {25},
  year      = {2017},
  abstract  = {This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC) or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model) with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950-2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood vulnerability.},
  language  = {en}
}
@phdthesis{Meier2017,
  author    = {Meier, Tobias},
  title     = {Borehole Breakouts in Transversely Isotropic Posidonia Shale},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400019},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xviii, 133},
  year      = {2017},
  abstract  = {Borehole instabilities are frequently encountered when drilling through finely laminated, organic rich shales ({\O}kland and Cook, 1998; Ottesen, 2010; etc.); such instabilities should be avoided to assure a successful exploitation and safe production of the contained unconventional hydrocarbons. Borehole instabilities, such as borehole breakouts or drilling induced tensile fractures, may lead to poor cementing of the borehole annulus, difficulties with recording and interpretation of geophysical logs, low directional control and in the worst case the loss of the well. If these problems are not recognized and expertly remedied, pollution of the groundwater or the emission of gases into the atmosphere can occur since the migration paths of the hydrocarbons in the subsurface are not yet fully understood (e.g., Davies et al., 2014; Zoback et al., 2010). In addition, it is often mentioned that the drilling problems encountered and the resulting downtimes of the wellbore system in finely laminated shales significantly increase drilling costs (Fjaer et al., 2008; Aadnoy and Ong, 2003). In order to understand and reduce the borehole instabilities during drilling in unconventional shales, we investigate stress-induced irregular extensions of the borehole diameter, which are also referred to as borehole breakouts. For this purpose, experiments with different borehole diameters, bedding plane angles and stress boundary conditions were performed on finely laminated Posidonia shales. The Lower Jurassic Posidonia shale is one of the most productive source rocks for conventional reservoirs in Europe and has the greatest potential for unconventional oil and gas in Europe (Littke et al., 2011). In this work, Posidonia shale specimens from the North (PN) and South (PS) German basins were selected and characterized petrophysically and mechanically. The composition of the two shales is dominated by calcite (47-56\%) followed by clays (23-28\%) and quartz (16-17\%). The remaining components are mainly pyrite and organic matter. The porosity of the shales varies considerably and is up to 10\% for PS and 1\% for PN, which is due to a larger deposition depth of PN. Both shales show marked elasticity and strength anisotropy, which can be attributed to a macroscopic distribution and orientation of soft and hard minerals. Under load the hard minerals form a load-bearing, supporting structure, while the soft minerals compensate the deformation. Therefore, if loaded parallel to the bedding, the Posidonia shale is more brittle than loaded normal to the bedding. The resulting elastic anisotropy, which can be defined by the ratio of the modulus of elasticity parallel and normal to the bedding, is about 50\%, while the strength anisotropy (i.e., the ratio of uniaxial compressive strength normal and parallel to the bedding) is up to 66\%. Based on the petrophysical characterization of the two rocks, a transverse isotropy (TVI) was derived. In general, PS is softer and weaker than PN, which is due to the stronger compaction of the material due to the higher burial depth. Conventional triaxial borehole breakout experiments on specimens with different borehole diameters showed that, when the diameter of the borehole is increased, the stress required to initiate borehole breakout decreases to a constant value. This value can be expressed as the ratio of the tangential stress and the uniaxial compressive strength of the rock. The ratio increases exponentially with decreasing borehole diameter from about 2.5 for a 10 mm diameter hole to ~ 7 for a 1 mm borehole (increase of initiation stress by 280\%) and can be described by a fracture mechanic based criterion. The reduction in borehole diameter is therefore a considerable aspect in reducing the risk of breakouts. New drilling techniques with significantly reduced borehole diameters, such as "fish-bone" holes, are already underway and are currently being tested (e.g., Xing et al., 2012). The observed strength anisotropy and the TVI material behavior are also reflected in the observed breakout processes at the borehole wall. Drill holes normal to the bedding develop breakouts in a plane of isotropy and are not affected by the strength or elasticity anisotropy. The observed breakouts are point-symmetric and form compressive shear failure planes, which can be predicted by a Mohr-Coulomb failure approach. If the shear failure planes intersect, conjugate breakouts can be described as "dog-eared" breakouts. While the initiation of breakouts for wells oriented normal to the stratification has been triggered by random local defects, reduced strengths parallel to bedding planes are the starting point for breakouts for wells parallel to the bedding. In the case of a deflected borehole trajectory, therefore, the observed failure type changes from shear-induced failure surfaces to buckling failure of individual layer packages. In addition, the breakout depths and widths increased, resulting in a stress-induced enlargement of the borehole cross-section and an increased output of rock material into the borehole. With the transition from shear to buckling failure and changing bedding plane angle with respect to the borehole axis, the stress required for inducing wellbore breakouts drops by 65\%. These observations under conventional triaxial stress boundary conditions could also be confirmed under true triaxial stress conditions. Here breakouts grew into the rock as a result of buckling failure, too. In this process, the broken layer packs rotate into the pressure-free drill hole and detach themselves from the surrounding rock by tensile cracking. The final breakout shape in Posidonia shale can be described as trapezoidal when the bedding planes are parallel to the greatest horizontal stress and to the borehole axis. In the event that the largest horizontal stress is normal to the stratification, breakouts were formed entirely by shear fractures between the stratification and required higher stresses to initiate similar to breakouts in conventional triaxial experiments with boreholes oriented normal to the bedding. In the content of this work, a fracture mechanics-based failure criterion for conventional triaxial loading conditions in isotropic rocks (Dresen et al., 2010) has been successfully extended to true triaxial loading conditions in the transverse isotropic rock to predict the initiation of borehole breakouts. The criterion was successfully verified on the experiments carried out. The extended failure criterion and the conclusions from the laboratory and numerical work may help to reduce the risk of borehole breakouts in unconventional shales.},
  language  = {en}
}
@phdthesis{Weege2017,
  author    = {Weege, Stefanie},
  title     = {Climatic drivers of retrogressive thaw slump activity and resulting sediment and carbon release to the nearshore zone of Herschel Island, Yukon Territory, Canada},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-397947},
  school      = {Universit{\"a}t Potsdam},
  pages     = {163},
  year      = {2017},
  abstract  = {The Yukon Coast in Canada is an ice-rich permafrost coast and highly sensitive to changing environmental conditions. Retrogressive thaw slumps are a common thermoerosion feature along this coast, and develop through the thawing of exposed ice-rich permafrost on slopes and removal of accumulating debris. They contribute large amounts of sediment, including organic carbon and nitrogen, to the nearshore zone. The objective of this study was to 1) identify the climatic and geomorphological drivers of sediment-meltwater release, 2) quantify the amount of released meltwater, sediment, organic carbon and nitrogen, and 3) project the evolution of sediment-meltwater release of retrogressive thaw slumps in a changing future climate. The analysis is based on data collected over 18 days in July 2013 and 18 days in August 2012. A cut-throat flume was set up in the main sediment-meltwater channel of the largest retrogressive thaw slump on Herschel Island. In addition, two weather stations, one on top of the undisturbed tundra and one on the slump floor, measured incoming solar radiation, air temperature, wind speed and precipitation. The discharge volume eroding from the ice-rich permafrost and retreating snowbanks was measured and compared to the meteorological data collected in real time with a resolution of one minute. The results show that the release of sediment-meltwater from thawing of the ice-rich permafrost headwall is strongly related to snowmelt, incoming solar radiation and air temperature. Snowmelt led to seasonal differences, especially due to the additional contribution of water to the eroding sediment-meltwater from headwall ablation, lead to dilution of the sediment-meltwater composition. Incoming solar radiation and air temperature were the main drivers for diurnal and inter-diurnal fluctuations. In July (2013), the retrogressive thaw slump released about 25 000 m³ of sediment-meltwater, containing 225 kg dissolved organic carbon and 2050 t of sediment, which in turn included 33 t organic carbon, and 4 t total nitrogen. In August (2012), just 15 600 m³ of sediment-meltwater was released, since there was no additional contribution from snowmelt. However, even without the additional dilution, 281 kg dissolved organic carbon was released. The sediment concentration was twice as high as in July, with sediment contents of up to 457 g l-1 and 3058 t of sediment, including 53 t organic carbon and 5 t nitrogen, being released. In addition, the data from the 36 days of observations from Slump D were upscaled to cover the main summer season of 1 July to 31 August (62 days) and to include all 229 active retrogressive thaw slumps along the Yukon Coast. In total, all retrogressive thaw slumps along the Yukon Coast contribute a minimum of 1.4 Mio. m³ sediment-meltwater each thawing season, containing a minimum of 172 000 t sediment with 3119 t organic carbon, 327 t nitrogen and 17 t dissolved organic carbon. Therefore, in addition to the coastal erosion input to the Beaufort Sea, retrogressive thaw slumps additionally release 3 \% of sediment and 8 \% of organic carbon into the ocean. Finally, the future evolution of retrogressive thaw slumps under a warming scenario with summer air temperatures increasing by 2-3 °C by 2081-2100, would lead to an increase of 109-114\% in release of sediment-meltwater. It can be concluded that retrogressive thaw slumps are sensitive to climatic conditions and under projected future Arctic warming will contribute larger amounts of thawed permafrost material (including organic carbon and nitrogen) into the environment.},
  language  = {en}
}
@phdthesis{Muldashev2017,
  author    = {Muldashev, Iskander},
  title     = {Modeling of the great earthquake seismic cycles},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-398926},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 117},
  year      = {2017},
  abstract  = {The timing and location of the two largest earthquakes of the 21st century (Sumatra, 2004 and Tohoku 2011, events) greatly surprised the scientific community, indicating that the deformation processes that precede and follow great megathrust earthquakes remain enigmatic. During these phases before and after the earthquake a combination of multi-scale complex processes are acting simultaneously: Stresses built up by long-term tectonic motions are modified by sudden jerky deformations during earthquakes, before being restored by multiple ensuing relaxation processes. This thesis details a cross-scale thermomechanical model developed with the aim of simulating the entire subduction process from earthquake (1 minute) to million years' time scale, excluding only rupture propagation. The model employs elasticity, non-linear transient viscous rheology, and rate-and-state friction. It generates spontaneous earthquake sequences, and, by using an adaptive time-step algorithm, recreates the deformation process as observed naturally over single and multiple seismic cycles. The model is thoroughly tested by comparing results to those from known high- resolution solutions of generic modeling setups widely used in modeling of rupture propagation. It is demonstrated, that while not modeling rupture propagation explicitly, the modeling procedure correctly recognizes the appearance of instability (earthquake) and correctly simulates the cumulative slip at a fault during great earthquake by means of a quasi-dynamic approximation. A set of 2D models is used to study the effects of non-linear transient rheology on the postseismic processes following great earthquakes. Our models predict that the viscosity in the mantle wedge drops by 3 to 4 orders of magnitude during a great earthquake with magnitude above 9. This drop in viscosity results in spatial scales and timings of the relaxation processes following the earthquakes that are significantly different to previous estimates. These models replicate centuries long seismic cycles exhibited by the greatest earthquakes (like the Great Chile 1960 Earthquake) and are consistent with the major features of postseismic surface displacements recorded after the Great Tohoku Earthquake. The 2D models are also applied to study key factors controlling maximum magnitudes of earthquakes in subduction zones. Even though methods of instrumentally observing earthquakes at subduction zones have rapidly improved in recent decades, the characteristic recurrence interval of giant earthquakes (Mw>8.5) is much larger than the currently available observational record and therefore the necessary conditions for giant earthquakes are not clear. Statistical studies have recognized the importance of the slab shape and its surface roughness, state of the strain of the upper plate and thickness of sediments filling the trenches. In this thesis we attempt to explain these observations and to identify key controlling parameters. We test a set of 2D models representing great earthquake seismic cycles at known subduction zones with various known geometries, megathrust friction coefficients, and convergence rates implemented. We found that low-angle subduction (large effect) and thick sediments in the subduction channel (smaller effect) are the fundamental necessary conditions for generating giant earthquakes, while the change of subduction velocity from 10 to 3.5 cm/yr has a lower effect. Modeling results also suggest that having thick sediments in the subduction channel causes low static friction, resulting in neutral or slightly compressive deformation in the overriding plate for low-angle subduction zones. These modeling results agree well with observations for the largest earthquakes. The model predicts the largest possible earthquakes for subduction zones of given dipping angles. The predicted maximum magnitudes exactly threshold magnitudes of all known giant earthquakes of 20th and 21st centuries. The clear limitation of most of the models developed in the thesis is their 2D nature. Development of 3D models with comparable resolution and complexity will require significant advances in numerical techniques. Nevertheless, we conducted a series of low-resolution 3D models to study the interaction between two large asperities at a subduction interface separated by an aseismic gap of varying width. The novelty of the model is that it considers behavior of the asperities during multiple seismic cycles. As expected, models show that an aseismic gap with a narrow width could not prevent rupture propagation from one asperity to another, and that rupture always crosses the entire model. When the gap becomes too wide, asperities do not interact anymore and rupture independently. However, an interesting mode of interaction was observed in the model with an intermediate width of the aseismic gap: In this model the asperities began to stably rupture in anti-phase following multiple seismic cycles. These 3D modeling results, while insightful, must be considered preliminary because of the limitations in resolution. The technique developed in this thesis for cross-scale modeling of seismic cycles can be used to study the effects of multiple seismic cycles on the long-term deformation of the upper plate. The technique can be also extended to the case of continental transform faults and for the advanced 3D modeling of specific subduction zones. This will require further development of numerical techniques and adaptation of the existing advanced highly scalable parallel codes like LAMEM and ASPECT.},
  language  = {en}
}
@phdthesis{Horn2017,
  author    = {Horn, Juliane},
  title     = {A modelling framework for exploration of a multidimensional factor causing decline in honeybee health},
  school      = {Universit{\"a}t Potsdam},
  pages     = {221},
  year      = {2017},
  language  = {en}
}
@phdthesis{Wolf2017,
  author    = {Wolf, Julia},
  title     = {Schadenserkennung in Beton durch {\"U}berwachung mit eingebetteten Ultraschallpr{\"u}fk{\"o}pfen},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-397363},
  school      = {Universit{\"a}t Potsdam},
  pages     = {ix, 142},
  year      = {2017},
  abstract  = {Die zerst{\"o}rungsfreien Pr{\"u}fungen von Bauwerken mit Hilfe von Ultraschallmessverfahren haben in den letzten Jahren an Bedeutung gewonnen. Durch Ultraschallmessungen k{\"o}nnen die Geometrien von Bauteilen bestimmt sowie von außen nicht sichtbare Fehler wie Delaminationen und Kiesnester erkannt werden. Mit neuartigen, in das Betonbauteil eingebetteten Ultraschallpr{\"u}fk{\"o}pfen sollen nun Bauwerke dauerhaft auf Ver{\"a}nderungen {\"u}berpr{\"u}ft werden. Dazu werden Ultraschallsignale direkt im Inneren eines Bauteils erzeugt, was die M{\"o}glichkeiten der herk{\"o}mmlichen Methoden der Bauwerks{\"u}berwachung wesentlich erweitert. Ein Ultraschallverfahren k{\"o}nnte mit eingebetteten Pr{\"u}fk{\"o}pfen ein Betonbauteil kontinuierlich integral {\"u}berwachen und damit auch stetig fortschreitende Gef{\"u}ge{\"a}nderungen, wie beispielsweise Mikrorisse, registrieren. Sicherheitsrelevante Bauteile, die nach dem Einbau f{\"u}r Messungen unzug{\"a}nglich oder mittels Ultraschall, beispielsweise durch zus{\"a}tzliche Beschichtungen der Oberfl{\"a}che, nicht pr{\"u}fbar sind, lassen sich mit eingebetteten Pr{\"u}fk{\"o}pfen {\"u}berwachen. An bereits vorhandenen Bauwerken k{\"o}nnen die Ultraschallpr{\"u}fk{\"o}pfe mithilfe von Bohrl{\"o}chern und speziellem Verpressm{\"o}rtel auch nachtr{\"a}glich in das Bauteil integriert werden. F{\"u}r Fertigbauteile bieten sich eingebettete Pr{\"u}fk{\"o}pfe zur Herstellungskontrolle sowie zur {\"U}berwachung der Baudurchf{\"u}hrung als Werkzeug der Qualit{\"a}tssicherung an. Auch die schnelle Schadensanalyse eines Bauwerks nach Naturkatastrophen, wie beispielsweise einem Erdbeben oder einer Flut, ist denkbar. Durch die gute Ankopplung erm{\"o}glichen diese neuartigen Pr{\"u}fk{\"o}pfe den Einsatz von empfindlichen Auswertungsmethoden, wie die Kreuzkorrelation, die Coda-Wellen-Interferometrie oder die Amplitudenauswertung, f{\"u}r die Signalanalyse. Bei regelm{\"a}ßigen Messungen k{\"o}nnen somit sich anbahnende Sch{\"a}den eines Bauwerks fr{\"u}hzeitig erkannt werden. Da die Sch{\"a}digung eines Bauwerks keine direkt messbare Gr{\"o}ße darstellt, erfordert eine eindeutige Schadenserkennung in der Regel die Messung mehrerer physikalischer Gr{\"o}ßen die geeignet verkn{\"u}pft werden. Physikalische Gr{\"o}ßen k{\"o}nnen sein: Ultraschalllaufzeit, Amplitude des Ultraschallsignals und Umgebungstemperatur. Dazu m{\"u}ssen Korrelationen zwischen dem Zustand des Bauwerks, den Umgebungsbedingungen und den Parametern des gemessenen Ultraschallsignals untersucht werden. In dieser Arbeit werden die neuartigen Pr{\"u}fk{\"o}pfe vorgestellt. Es wird beschrieben, dass sie sich, sowohl in bereits errichtete Betonbauwerke als auch in der Konstruktion befindliche, einbauen lassen. Experimentell wird gezeigt, dass die Pr{\"u}fk{\"o}pfe in mehreren Ebenen eingebettet sein k{\"o}nnen da ihre Abstrahlcharakteristik im Beton nahezu ungerichtet ist. Die Mittenfrequenz von rund 62 kHz erm{\"o}glicht Abst{\"a}nde, je nach Betonart und SRV, von mindestens 3 m zwischen Pr{\"u}fk{\"o}pfen die als Sender und Empf{\"a}nger arbeiten. Die Empfindlichkeit der eingebetteten Pr{\"u}fk{\"o}pfe gegen{\"u}ber Ver{\"a}nderungen im Beton wird an Hand von zwei Laborexperimenten gezeigt, einem Drei-Punkt-Biegeversuch und einem Versuch zur Erzeugung von Frost-Tau-Wechsel Sch{\"a}den. Die Ergebnisse werden mit anderen zerst{\"o}rungsfreien Pr{\"u}fverfahren verglichen. Es zeigt sich, dass die Pr{\"u}fk{\"o}pfe durch die Anwendung empfindlicher Auswertemethoden, auftretende Risse im Beton detektieren, bevor diese eine Gefahr f{\"u}r das Bauwerk darstellen. Abschließend werden Beispiele von Installation der neuartigen Ultraschallpr{\"u}fk{\"o}pfe in realen Bauteilen, zwei Br{\"u}cken und einem Fundament, gezeigt und basierend auf dort gewonnenen ersten Erfahrungen ein Konzept f{\"u}r die Umsetzung einer Langzeit{\"u}berwachung aufgestellt.},
  language  = {de}
}
@inproceedings{LopezTarazonBronstertThiekenetal.2017,
  author    = {L{\´o}pez-Taraz{\´o}n, Jos{\´e} Andr{\´e}s and Bronstert, Axel and Thieken, Annegret and Petrow, Theresia},
  title     = {International symposium on the effects of global change on floods, fluvial geomorphology and related hazards in mountainous rivers},
  series = {Book of Abstracts},
  booktitle = {Book of Abstracts},
  editor    = {L{\´o}pez-Taraz{\´o}n, Jos{\´e} Andr{\´e}s and Bronstert, Axel and Thieken, Annegret and Petrow, Theresia},
  organization    = {Universit{\"a}t Potsdam},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-396922},
  pages     = {104},
  year      = {2017},
  abstract  = {Both Alpine and Mediterranean areas are considered sensitive to so-called global change, considered as the combination of climate and land use changes. All panels on climate evolution predict future scenarios of increasing frequency and magnitude of floods which are likely to lead to huge geomorphic adjustments of river channels so major metamorphosis of fluvial systems is expected as a result of global change. Such pressures are likely to give rise to major ecological and economic changes and challenges that governments need to address as a matter of priority. Changes in river flow regimes associated with global change are therefore ushering in a new era, where there is a critical need to evaluate hydro-geomorphological hazards from headwaters to lowland areas (flooding can be not just a problem related to being under the water). A key question is how our understanding of these hazards associated with global change can be improved; improvement has to come from integrated research which includes the climatological and physical conditions that could influence the hydrology and sediment generation and hence the conveyance of water and sediments (including the river's capacity, i.e. amount of sediment, and competence, i.e. channel deformation) and the vulnerabilities and economic repercussions of changing hydrological hazards (including the evaluation of the hydro-geomorphological risks too). Within this framework, the purpose of this international symposium is to bring together researchers from several disciplines as hydrology, fluvial geomorphology, hydraulic engineering, environmental science, geography, economy (and any other related discipline) to discuss the effects of global change over the river system in relation with floods. The symposium is organized by means of invited talks given by prominent experts, oral lectures, poster sessions and discussion sessions for each individual topic; it will try to improve our understanding of how rivers are likely to evolve as a result of global change and hence address the associated hazards of that fluvial environmental change concerning flooding. Four main topics are going to be addressed: - Modelling global change (i.e. climate and land-use) at relevant spatial (regional, local) and temporal (from the long-term to the single-event) scales. - Measuring and modelling river floods from the hydrological, sediment transport (both suspended and bedload) and channel morphology points of view at different spatial (from the catchment to the reach) and temporal (from the long-term to the single-event) scales. - Evaluation and assessment of current and future river flooding hazards and risks in a global change perspective. - Catchment management to face river floods in a changing world. We are very pleased to welcome you to Potsdam. We hope you will enjoy your participation at the International Symposium on the Effects of Global Change on Floods, Fluvial Geomorphology and Related Hazards in Mountainous Rivers and have an exciting and profitable experience. Finally, we would like to thank all speakers, participants, supporters, and sponsors for their contributions that for sure will make of this event a very remarkable and fruitful meeting. We acknowledge the valuable support of the European Commission (Marie Curie Intra-European Fellowship, Project ''Floodhazards'', PIEF-GA-2013-622468, Seventh EU Framework Programme) and the Deutschen Forschungsgemeinschaft (Research Training Group "Natural Hazards and Risks in a Changing World" (NatRiskChange; GRK 2043/1) as the symposium would not have been possible without their help. Without your cooperation, this symposium would not be either possible or successful.},
  language  = {en}
}
@misc{PurintonBookhagen2017,
  author    = {Purinton, Benjamin and Bookhagen, Bodo},
  title     = {Validation of digital elevation models (DEMs) and comparison of geomorphic metrics on the southern Central Andean Plateau},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-396277},
  pages     = {27},
  year      = {2017},
  abstract  = {In this study, we validate and compare elevation accuracy and geomorphic metrics of satellite-derived digital elevation models (DEMs) on the southern Central Andean Plateau. The plateau has an average elevation of 3.7 km and is characterized by diverse topography and relief, lack of vegetation, and clear skies that create ideal conditions for remote sensing. At 30m resolution, SRTM-C, ASTER GDEM2, stacked ASTER L1A stereopair DEM, ALOS World 3D, and TanDEM-X have been analyzed. The higher-resolution datasets include 12m TanDEM-X, 10m single-CoSSC TerraSAR-X/TanDEM-X DEMs, and 5m ALOS World 3D. These DEMs are state of the art for optical (ASTER and ALOS) and radar (SRTM-C and TanDEM-X) spaceborne sensors. We assessed vertical accuracy by comparing standard deviations of the DEM elevation versus 307 509 differential GPS measurements across 4000m of elevation. For the 30m DEMs, the ASTER datasets had the highest vertical standard deviation at > 6.5 m, whereas the SRTM-C, ALOS World 3D, and TanDEM-X were all < 3.5 m. Higher-resolution DEMs generally had lower uncertainty, with both the 12m TanDEM-X and 5m ALOSWorld 3D having < 2m vertical standard deviation. Analysis of vertical uncertainty with respect to terrain elevation, slope, and aspect revealed the low uncertainty across these attributes for SRTM-C (30 m), TanDEM-X (12-30 m), and ALOS World 3D (5-30 m). Single-CoSSC TerraSAR-X/TanDEM-X 10m DEMs and the 30m ASTER GDEM2 displayed slight aspect biases, which were removed in their stacked counterparts (TanDEM-X and ASTER Stack). Based on low vertical standard deviations and visual inspection alongside optical satellite data, we selected the 30m SRTM-C, 12-30m TanDEM-X, 10m single-CoSSC TerraSAR-X/TanDEM-X, and 5m ALOS World 3D for geomorphic metric comparison in a 66 km2 catchment with a distinct river knickpoint. Consistent m=n values were found using chi plot channel profile analysis, regardless of DEM type and spatial resolution. Slope, curvature, and drainage area were calculated and plotting schemes were used to assess basin-wide differences in the hillslope-to-valley transition related to the knickpoint. While slope and hillslope length measurements vary little between datasets, curvature displays higher magnitude measurements with fining resolution. This is especially true for the optical 5m ALOS World 3D DEM, which demonstrated high-frequency noise in 2-8 pixel steps through a Fourier frequency analysis. The improvements in accurate space-radar DEMs (e.g., TanDEM-X) for geomorphometry are promising, but airborne or terrestrial data are still necessary for meter-scale analysis.},
  language  = {en}
}
@article{PurintonBookhagen2017,
  author    = {Purinton, Benjamin and Bookhagen, Bodo},
  title     = {Validation of digital elevation models (DEMs) and comparison of geomorphic metrics on the southern Central Andean Plateau},
  series = {Earth surface dynamics},
  volume    = {5},
  journal   = {Earth surface dynamics},
  number    = {2},
  publisher = {Copernicus Publ.},
  address   = {G{\"o}ttingen},
  issn      = {2196-632X},
  doi       = {10.5194/esurf-5-211-2017},
  pages     = {211 -- 237},
  year      = {2017},
  abstract  = {In this study, we validate and compare elevation accuracy and geomorphic metrics of satellite-derived digital elevation models (DEMs) on the southern Central Andean Plateau. The plateau has an average elevation of 3.7 km and is characterized by diverse topography and relief, lack of vegetation, and clear skies that create ideal conditions for remote sensing. At 30m resolution, SRTM-C, ASTER GDEM2, stacked ASTER L1A stereopair DEM, ALOS World 3D, and TanDEM-X have been analyzed. The higher-resolution datasets include 12m TanDEM-X, 10m single-CoSSC TerraSAR-X/TanDEM-X DEMs, and 5m ALOS World 3D. These DEMs are state of the art for optical (ASTER and ALOS) and radar (SRTM-C and TanDEM-X) spaceborne sensors. We assessed vertical accuracy by comparing standard deviations of the DEM elevation versus 307 509 differential GPS measurements across 4000m of elevation. For the 30m DEMs, the ASTER datasets had the highest vertical standard deviation at > 6.5 m, whereas the SRTM-C, ALOS World 3D, and TanDEM-X were all < 3.5 m. Higher-resolution DEMs generally had lower uncertainty, with both the 12m TanDEM-X and 5m ALOSWorld 3D having < 2m vertical standard deviation. Analysis of vertical uncertainty with respect to terrain elevation, slope, and aspect revealed the low uncertainty across these attributes for SRTM-C (30 m), TanDEM-X (12-30 m), and ALOS World 3D (5-30 m). Single-CoSSC TerraSAR-X/TanDEM-X 10m DEMs and the 30m ASTER GDEM2 displayed slight aspect biases, which were removed in their stacked counterparts (TanDEM-X and ASTER Stack). Based on low vertical standard deviations and visual inspection alongside optical satellite data, we selected the 30m SRTM-C, 12-30m TanDEM-X, 10m single-CoSSC TerraSAR-X/TanDEM-X, and 5m ALOS World 3D for geomorphic metric comparison in a 66 km2 catchment with a distinct river knickpoint. Consistent m=n values were found using chi plot channel profile analysis, regardless of DEM type and spatial resolution. Slope, curvature, and drainage area were calculated and plotting schemes were used to assess basin-wide differences in the hillslope-to-valley transition related to the knickpoint. While slope and hillslope length measurements vary little between datasets, curvature displays higher magnitude measurements with fining resolution. This is especially true for the optical 5m ALOS World 3D DEM, which demonstrated high-frequency noise in 2-8 pixel steps through a Fourier frequency analysis. The improvements in accurate space-radar DEMs (e.g., TanDEM-X) for geomorphometry are promising, but airborne or terrestrial data are still necessary for meter-scale analysis.},
  language  = {en}
}
@misc{DidovetsLobanovaBronstertetal.2017,
  author    = {Didovets, Iulii and Lobanova, Anastasia and Bronstert, Axel and Snizhko, Sergiy and Maule, Cathrine Fox and Krysanova, Valentina},
  title     = {Assessment of Climate Change Impacts on Water Resources in Three Representative Ukrainian Catchments Using Eco-Hydrological Modelling},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-394956},
  pages     = {18},
  year      = {2017},
  abstract  = {The information about climate change impact on river discharge is vitally important for planning adaptation measures. The future changes can affect different water-related sectors. The main goal of this study was to investigate the potential water resource changes in Ukraine, focusing on three mesoscale river catchments (Teteriv, UpperWestern Bug, and Samara) characteristic for different geographical zones. The catchment scale watershed model—Soil and Water Integrated Model (SWIM)—was setup, calibrated, and validated for the three catchments under consideration. A set of seven GCM-RCM (General Circulation Model-Regional Climate Model) coupled climate scenarios corresponding to RCPs (Representative Concentration Pathways) 4.5 and 8.5 were used to drive the hydrological catchment model. The climate projections, used in the study, were considered as three combinations of low, intermediate, and high end scenarios. Our results indicate the shifts in the seasonal distribution of runoff in all three catchments. The spring high flow occurs earlier as a result of temperature increases and earlier snowmelt. The fairly robust trend is an increase in river discharge in the winter season, and most of the scenarios show a potential decrease in river discharge in the spring.},
  language  = {en}
}
@article{DidovetsLobanovaBronstertetal.2017,
  author    = {Didovets, Iulii and Lobanova, Anastasia and Bronstert, Axel and Snizhko, Sergiy and Maule, Cathrine Fox and Krysanova, Valentina},
  title     = {Assessment of Climate Change Impacts on Water Resources in Three Representative Ukrainian Catchments Using Eco-Hydrological Modelling},
  series = {Water},
  volume    = {9},
  journal   = {Water},
  number    = {3},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4441},
  doi       = {10.3390/w9030204},
  pages     = {18},
  year      = {2017},
  abstract  = {The information about climate change impact on river discharge is vitally important for planning adaptation measures. The future changes can affect different water-related sectors. The main goal of this study was to investigate the potential water resource changes in Ukraine, focusing on three mesoscale river catchments (Teteriv, UpperWestern Bug, and Samara) characteristic for different geographical zones. The catchment scale watershed model—Soil and Water Integrated Model (SWIM)—was setup, calibrated, and validated for the three catchments under consideration. A set of seven GCM-RCM (General Circulation Model-Regional Climate Model) coupled climate scenarios corresponding to RCPs (Representative Concentration Pathways) 4.5 and 8.5 were used to drive the hydrological catchment model. The climate projections, used in the study, were considered as three combinations of low, intermediate, and high end scenarios. Our results indicate the shifts in the seasonal distribution of runoff in all three catchments. The spring high flow occurs earlier as a result of temperature increases and earlier snowmelt. The fairly robust trend is an increase in river discharge in the winter season, and most of the scenarios show a potential decrease in river discharge in the spring.},
  language  = {en}
}
@phdthesis{Kellermann2017,
  author    = {Kellermann, Patric},
  title     = {Assessing natural risks for railway infrastructure and transportation in Austria},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-103877},
  school      = {Universit{\"a}t Potsdam},
  pages     = {x, 113},
  year      = {2017},
  abstract  = {Natural hazards can have serious societal and economic impacts. Worldwide, around one third of economic losses due to natural hazards are attributable to floods. The majority of natural hazards are triggered by weather-related extremes such as heavy precipitation, rapid snow melt, or extreme temperatures. Some of them, and in particular floods, are expected to further increase in terms of frequency and/or intensity in the coming decades due to the impacts of climate change. In this context, the European Alps areas are constantly disclosed as being particularly sensitive. In order to enhance the resilience of societies to natural hazards, risk assessments are substantial as they can deliver comprehensive risk information to be used as a basis for effective and sustainable decision-making in natural hazards management. So far, current assessment approaches mostly focus on single societal or economic sectors - e.g. flood damage models largely concentrate on private-sector housing - and other important sectors, such as the transport infrastructure sector, are widely neglected. However, transport infrastructure considerably contributes to economic and societal welfare, e.g. by ensuring mobility of people and goods. In Austria, for example, the national railway network is essential for the European transit of passengers and freights as well as for the development of the complex Alpine topography. Moreover, a number of recent experiences show that railway infrastructure and transportation is highly vulnerable to natural hazards. As a consequence, the Austrian Federal Railways had to cope with economic losses on the scale of several million euros as a result of flooding and other alpine hazards. The motivation of this thesis is to contribute to filling the gap of knowledge about damage to railway infrastructure caused by natural hazards by providing new risk information for actors and stakeholders involved in the risk management of railway transportation. Hence, in order to support the decision-making towards a more effective and sustainable risk management, the following two shortcomings in natural risks research are approached: i) the lack of dedicated models to estimate flood damage to railway infrastructure, and ii) the scarcity of insights into possible climate change impacts on the frequency of extreme weather events with focus on future implications for railway transportation in Austria. With regard to flood impacts to railway infrastructure, the empirically derived damage model Railway Infrastructure Loss (RAIL) proved expedient to reliably estimate both structural flood damage at exposed track sections of the Northern Railway and resulting repair cost. The results show that the RAIL model is capable of identifying flood risk hot spots along the railway network and, thus, facilitates the targeted planning and implementation of (technical) risk reduction measures. However, the findings of this study also show that the development and validation of flood damage models for railway infrastructure is generally constrained by the continuing lack of detailed event and damage data. In order to provide flood risk information on the large scale to support strategic flood risk management, the RAIL model was applied for the Austrian Mur River catchment using three different hydraulic scenarios as input as well as considering an increased risk aversion of the railway operator. Results indicate that the model is able to deliver comprehensive risk information also on the catchment level. It is furthermore demonstrated that the aspect of risk aversion can have marked influence on flood damage estimates for the study area and, hence, should be considered with regard to the development of risk management strategies. Looking at the results of the investigation on future frequencies of extreme weather events jeopardizing railway infrastructure and transportation in Austria, it appears that an increase in intense rainfall events and heat waves has to be expected, whereas heavy snowfall and cold days are likely to decrease. Furthermore, results indicate that frequencies of extremes are rather sensitive to changes of the underlying thresholds. It thus emphasizes the importance to carefully define, validate, and — if needed — to adapt the thresholds that are used to detect and forecast meteorological extremes. For this, continuous and standardized documentation of damaging events and near-misses is a prerequisite. Overall, the findings of the research presented in this thesis agree on the necessity to improve event and damage documentation procedures in order to enable the acquisition of comprehensive and reliable risk information via risk assessments and, thus, support strategic natural hazards management of railway infrastructure and transportation.},
  language  = {en}
}