@article{TellaWinterleitnerMorsillietal.2022, author = {Tella, Timothy O. and Winterleitner, Gerd and Morsilli, Michele and Mutti, Maria}, title = {Testing sea-level and carbonate production effects on stratal architecture of a distally steepened carbonate ramp (Upper Miocene, Menorca)}, series = {Sedimentary geology : international journal of applied and regional sedimentology}, volume = {441}, journal = {Sedimentary geology : international journal of applied and regional sedimentology}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, issn = {0037-0738}, doi = {10.1016/j.sedgeo.2022.106267}, pages = {18}, year = {2022}, abstract = {Although distally steepened carbonate ramps have been studied by numerous researchers, the processes that control the development of these carbonate systems, including tectonics, differential carbonate production along the ramp profile, or antecedent physiography of the slopes, are an ongoing discussion. We use a stratigraphic forward model to test different hypotheses to unravel controls over distally steepened ramp development, referenced to the well-known Upper Miocene Menorca carbonate ramp (Spain). Sensitivity tests show that distally steepened ramps develop under complex interaction among accommodation, carbonate production and sediment transport parameters. Ramp slope initiation is favoured by still stands and falls of sea-level, in a setting with high-frequency sea-level fluctuations with amplitude between 20 m and 40 m. Low-frequency and higher amplitude sea-level fluctuations of about 115 m tend to form models with no significant slope development. The impact of antecedent slope on the geometry of ramps is determined by the paleoslope inclination, with flat to subhorizontal paleosurfaces resulting in ramps that mirror the antecedent slope. In contrast, steeper paleosurfaces tend to result in ramps with well-defined slopes. Our models, therefore, show that the ramp profile becomes more influenced by the depth constraints on the carbonate sediment producers than by the geometry of the underlying topography as the inclination of the paleosurface increases. The presented models also show that seagrass-dominated shallow carbonate production tends to result in steep slopes due to the low-transport characteristic imposed by seagrass trapping. This steepness can, however, be altered by the introduction of high transport sediment grains from deeper carbonate producers, which fill the slopes and more distal sections of the ramp profile.}, language = {en} } @article{KnappAttingerHuth2022, author = {Knapp, Nikolai and Attinger, Sabine and Huth, Andreas}, title = {A question of scale: modeling biomass, gain and mortality distributions of a tropical forest}, series = {Biogeosciences}, volume = {19}, journal = {Biogeosciences}, number = {20}, publisher = {Copernicus}, address = {Katlenburg-Lindau [u.a.]}, issn = {1726-4170}, doi = {10.5194/bg-19-4929-2022}, pages = {4929 -- 4944}, year = {2022}, abstract = {Describing the heterogeneous structure of forests is often challenging. One possibility is to analyze forest biomass in different plots and to derive plot-based frequency distributions. However, these frequency distributions depend on the plot size and thus are scale dependent. This study provides insights about transferring them between scales. Understanding the effects of scale on distributions of biomass is particularly important for comparing information from different sources such as inventories, remote sensing and modeling, all of which can operate at different spatial resolutions. Reliable methods to compare results of vegetation models at a grid scale with field data collected at smaller scales are still missing. The scaling of biomass and variables, which determine the forest biomass, was investigated for a tropical forest in Panama. Based on field inventory data from Barro Colorado Island, spanning 50 ha over 30 years, the distributions of aboveground biomass, biomass gain and mortality were derived at different spatial resolutions, ranging from 10 to 100 m. Methods for fitting parametric distribution functions were compared. Further, it was tested under which assumptions about the distributions a simple stochastic simulation forest model could best reproduce observed biomass distributions at all scales. Also, an analytical forest model for calculating biomass distributions at equilibrium and assuming mortality as a white shot noise process was tested. Scaling exponents of about 0.47 were found for the standard deviations of the biomass and gain distributions, while mortality showed a different scaling relationship with an exponent of 0.3. Lognormal and gamma distribution functions fitted with the moment matching estimation method allowed for consistent parameter transfers between scales. Both forest models (stochastic simulation and analytical solution) were able to reproduce observed biomass distributions across scales, when combined with the derived scaling relationships. The study demonstrates a way of how to approach the scaling problem in model-data comparisons by providing a transfer relationship. Further research is needed for a better understanding of the mechanisms that shape the frequency distributions at the different scales.}, language = {en} } @phdthesis{FernandezPalomino2024, author = {Fernandez Palomino, Carlos Antonio}, title = {Understanding hydrological dynamics in the tropical Andes of Peru and Ecuador and their responses to climate change}, doi = {10.25932/publishup-65653}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-656534}, school = {Universit{\"a}t Potsdam}, pages = {160}, year = {2024}, abstract = {Human-induced climate change is impacting the global water cycle by, e.g., causing changes in precipitation patterns, evapotranspiration dynamics, cryosphere shrinkage, and complex streamflow trends. These changes, coupled with the increased frequency and severity of extreme hydrometeorological events like floods, droughts, and heatwaves, contribute to hydroclimatic disasters, posing significant implications for local and global infrastructure, human health, and overall productivity. In the tropical Andes, climate change is evident through warming trends, glacier retreats, and shifts in precipitation patterns, leading to altered risks of floods and droughts, e.g., in the upper Amazon River basin. Projections for the region indicate rising temperatures, potential glacier disappearance or substantial shrinkage, and altered streamflow patterns, highlighting challenges in water availability due to these expected changes and growing human water demand. The evolving trends in hydroclimatic conditions in the tropical Andes present significant challenges to socioeconomic and environmental systems, emphasizing the need for a comprehensive understanding to guide effective adaptation policies and strategies in response to the impacts of climate change in the region. The main objective of this thesis is to investigate current hydrological dynamics in the tropical Andes of Peru and Ecuador and their responses to climate change. Given the scarcity of hydrometeorological data in the region, this objective was accomplished through a comprehensive data preparation and analysis in combination with hydrological modeling using the Soil and Water Assessment Tool (SWAT) eco-hydrological model. In this context, the initial steps involved assessing, identifying, and/or generating more reliable climate input data to address data limitations. The thesis introduces RAIN4PE, a high-resolution precipitation dataset for Peru and Ecuador, developed by merging satellite, reanalysis, and ground-based data with surface elevation through the random forest method. Further adjustments of precipitation estimates were made for catchments influenced by fog/cloud water input on the eastern side of the Andes using streamflow data and applying the method of reverse hydrology. RAIN4PE surpasses other global and local precipitation datasets, showcasing superior reliability and accuracy in representing precipitation patterns and simulating hydrological processes across the tropical Andes. This establishes it as the optimal precipitation product for hydrometeorological applications in the region. Due to the significant biases and limitations of global climate models (GCMs) in representing key atmospheric variables over the tropical Andes, this study developed regionally adapted GCM simulations specifically tailored for Peru and Ecuador. These simulations are known as the BASD-CMIP6-PE dataset, and they were derived using reliable, high-resolution datasets like RAIN4PE as reference data. The BASD-CMIP6-PE dataset shows notable improvements over raw GCM simulations, reflecting enhanced representations of observed climate properties and accurate simulation of streamflow, including high and low flow indices. This renders it suitable for assessing regional climate change impacts on agriculture, water resources, and hydrological extremes. In addition to generating more accurate climatic input data, a reliable hydrological model is essential for simulating watershed hydrological processes. To tackle this challenge, the thesis presents an innovative multiobjective calibration framework integrating remote sensing vegetation data, baseflow index, discharge goodness-of-fit metrics, and flow duration curve signatures. In contrast to traditional calibration strategies relying solely on discharge goodness-of-fit metrics, this approach enhances the simulation of vegetation, streamflow, and the partitioning of flow into surface runoff and baseflow in a typical Andean catchment. The refined hydrological model calibration strategy was applied to conduct reliable simulations and understand current and future hydrological trajectories in the tropical Andes. By establishing a region-suitable and thoroughly tested hydrological model with high-resolution and reliable precipitation input data from RAIN4PE, this study provides new insights into the spatiotemporal distribution of water balance components in Peru and transboundary catchments. Key findings underscore the estimation of Peru's total renewable freshwater resource (total river runoff of 62,399 m3/s), with the Peruvian Amazon basin contributing 97.7\%. Within this basin, the Amazon-Andes transition region emerges as a pivotal hotspot for water yield (precipitation minus evapotranspiration), characterized by abundant rainfall and lower atmospheric water demand/evapotranspiration. This finding underlines its paramount role in influencing the hydrological variability of the entire Amazon basin. Subsurface hydrological pathways, particularly baseflow from aquifers, strongly influence water yield in lowland and Andean catchments, sustaining streamflow, especially during the extended dry season. Water yield demonstrates an elevation- and latitude-dependent increase in the Pacific Basin (catchments draining into the Pacific Ocean), while it follows an unimodal curve in the Peruvian Amazon Basin, peaking in the Amazon-Andes transition region. This observation indicates an intricate relationship between water yield and elevation. In Amazon lowlands rivers, particularly in the Ucayali River, floodplains play a significant role in shaping streamflow seasonality by attenuating and delaying peak flows for up to two months during periods of high discharge. This observation underscores the critical importance of incorporating floodplain dynamics into hydrological simulations and river management strategies for accurate modeling and effective water resource management. Hydrological responses vary across different land use types in high Andean catchments. Pasture areas exhibit the highest water yield, while agricultural areas and mountain forests show lower yields, emphasizing the importance of puna (high-altitude) ecosystems, such as pastures, p{\´a}ramos, and bofedales, in regulating natural storage. Projected future hydrological trajectories were analyzed by driving the hydrological model with regionalized GCM simulations provided by the BASD-CMIP6-PE dataset. The analysis considered sustainable (low warming, SSP1-2.6) and fossil fuel-based development (high-end warming, SSP5-8.5) scenarios for the mid (2035-2065) and end (2065-2095) of the century. The projected changes in water yield and streamflow across the tropical Andes exhibit distinct regional and seasonal variations, particularly amplified under a high-end warming scenario towards the end of the century. Projections suggest year-round increases in water yield and streamflow in the Andean regions and decreases in the Amazon lowlands, with exceptions such as the northern Amazon expecting increases during wet seasons. Despite these regional differences, the upper Amazon River's streamflow is projected to remain relatively stable throughout the 21st century. Additionally, projections anticipate a decrease in low flows in the Amazon lowlands and an increased risk of high flows (floods) in the Andean and northern Amazon catchments. This thesis significantly contributes to enhancing climatic data generation, overcoming regional limitations that previously impeded hydrometeorological research, and creating new opportunities. It plays a crucial role in advancing hydrological model calibration, improving the representation of internal hydrological processes, and achieving accurate results for the right reasons. Novel insights into current hydrological dynamics in the tropical Andes are fundamental for improving water resource management. The anticipated intensified changes in water flows and hydrological extreme patterns under a high-end warming scenario highlight the urgency of implementing emissions mitigation and adaptation measures to address the heightened impacts on water resources. In fact, the new datasets (RAIN4PE and BASD-CMIP6-PE) have already been utilized by researchers and experts in regional and local-scale projects and catchments in Peru and Ecuador. For instance, they have been applied in river catchments such as Mantaro, Piura, and San Pedro to analyze local historical and future developments in climate and water resources.}, language = {en} } @article{VyseHerzschuhPfalzetal.2021, author = {Vyse, Stuart A. and Herzschuh, Ulrike and Pfalz, Gregor and Pestryakova, Lyudmila A. and Diekmann, Bernhard and Nowaczyk, Norbert and Biskaborn, Boris K.}, title = {Sediment and carbon accumulation in a glacial lake in Chukotka (Arctic Siberia) during the Late Pleistocene and Holocene}, series = {Biogeosciences}, volume = {18}, journal = {Biogeosciences}, number = {16}, publisher = {Copernicus}, address = {Katlenburg-Lindau}, issn = {1726-4170}, doi = {10.5194/bg-18-4791-2021}, pages = {4791 -- 4816}, year = {2021}, abstract = {Lakes act as important sinks for inorganic and organic sediment components. However, investigations of sedimentary carbon budgets within glacial lakes are currently absent from Arctic Siberia. The aim of this paper is to provide the first reconstruction of accumulation rates, sediment and carbon budgets from a lacustrine sediment core from Lake Rauchuagytgyn, Chukotka (Arctic Siberia). We combined multiple sediment biogeochemical and sedimentological parameters from a radiocarbon-dated 6.5m sediment core with lake basin hydroacoustic data to derive sediment stratigraphy, sediment volumes and infill budgets. Our results distinguished three principal sediment and carbon accumulation regimes that could be identified across all measured environmental proxies including early Marine Isotope Stage 2 (MIS2) (ca. 29-23.4 ka cal BP), mid-MIS2-early MIS1 (ca. 23.4-11.69 ka cal BP) and the Holocene (ca. 11.69-present). Estimated organic carbon accumulation rates (OCARs) were higher within Holocene sediments (average 3.53 gOCm(-2) a(-1)) than Pleistocene sediments (average 1.08 gOCm(-2) a(-1)) and are similar to those calculated for boreal lakes from Quebec and Finland and Lake Baikal but significantly lower than Siberian thermokarst lakes and Alberta glacial lakes. Using a bootstrapping approach, we estimated the total organic carbon pool to be 0.26 +/- 0.02 Mt and a total sediment pool of 25.7 +/- 1.71 Mt within a hydroacoustically derived sediment volume of ca. 32 990 557m(3). The total organic carbon pool is substantially smaller than Alaskan yedoma, thermokarst lake sediments and Alberta glacial lakes but shares similarities with Finnish boreal lakes. Temporal variability in sediment and carbon accumulation dynamics at Lake Rauchuagytgyn is controlled predominantly by palaeoclimate variation that regulates lake ice-cover dynamics and catchment glacial, fluvial and permafrost processes through time. These processes, in turn, affect catchment and within-lake primary productivity as well as catchment soil development. Spatial differences compared to other lake systems at a trans-regional scale likely relate to the high-latitude, mountainous location of Lake Rauchuagytgyn.}, language = {en} } @article{MohrMangaHelleetal.2021, author = {Mohr, Christian H. and Manga, Michael and Helle, Gerhard and Heinrich, Ingo and Giese, Laura and Korup, Oliver}, title = {Trees talk tremor-wood anatomy and δ13C content reveal contrasting tree-growth responses to earthquakes}, series = {JGR / AGU, American Geophysical Union. Biogeosciences}, volume = {126}, journal = {JGR / AGU, American Geophysical Union. Biogeosciences}, number = {10}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {2169-8953}, doi = {10.1029/2021JG006385}, pages = {17}, year = {2021}, abstract = {Large earthquakes can increase the amount of water feeding stream flows, raise groundwater levels, and thus grant plant roots more access to water in water-limited environments. We examine growth and photosynthetic responses of Pine plantations to the Maule M-w 8.8 earthquake in headwater catchments of Chile's Coastal Range. We combine high-resolution wood anatomic (lumen area) and biogeochemical (delta 13C of wood cellulose) proxies of daily to weekly tree growth sampled from trees on floodplains and close to ridge lines. We find that, immediately after the earthquake, at least two out of six tree trees on valley floors had increased lumen area and decreased delta 13C, while trees on hillslopes had a reverse trend. Our results indicate a control of soil water on this response, largely consistent with models that predict how enhanced postseismic vertical soil permeability causes groundwater levels to rise on valley floors, but fall along the ridges. Statistical analysis with boosted regression trees indicates that streamflow discharge gained predictive importance for photosynthetic activity on the ridges, but lost importance on the valley floor after the earthquake. We infer that earthquakes may stimulate ecohydrological conditions favoring tree growth over days to weeks by triggering stomatal opening. The weak and short-lived signals that we identified, however, show that such responses are only valid under water-limited, rather than energy-limited tree, growth. Hence, dendrochronological studies targeted at annual resolution may overlook some earthquake effects on tree vitality.}, language = {en} } @article{CannoneGuglielminMalfasietal.2021, author = {Cannone, Nicoletta and Guglielmin, Mauro and Malfasi, Francesco and Hubberten, Hans Wolfgang and Wagner, Dirk}, title = {Rapid soil and vegetation changes at regional scale in continental Antarctica}, series = {Geoderma : an international journal of soil science}, volume = {394}, journal = {Geoderma : an international journal of soil science}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0016-7061}, doi = {10.1016/j.geoderma.2021.115017}, pages = {16}, year = {2021}, abstract = {Antarctica is the last pristine environment on Earth, its biota being adapted to the harsh and extreme polar climate. Until now, soil formation and vegetation development in continental Antarctica were considered very slow due to the extreme conditions of this polar desert. Since the austral summer 2002/2003, a long-term monitoring network of the terrestrial ecosystems (soils, vegetation, active layer thickness) has been established at Victoria Land (VL) across a > 500 km latitudinal gradient of coastal sites (73 degrees -77 degrees S). In only one decade large ecosystem changes were detected. Climate was characterized by a significant increase of thawing degree days in northern VL and of autumn air temperature. No extreme climatic events (such as hot spells) where detected in the study period. Soil chemistry suffered large quantitative changes, clearly indicating rapid pedogenetic processes. In most soils the upper layers exhibited a strong alkalinization (pH increases up to 3 units) and increases in conductivity, anions and cations (in particular of SO4 and Na). The largest changes were observed in soils with low vegetation cover. Statistically significant differences in soil chemistry were detected between soils with high and low vegetation cover, the former showing lower pH, conductivity, Na and Cl. Most plots exhibited changes of total cover, species richness and floristic composition, with vegetation expansion in soils with low vegetation cover and the largest increase recorded at Apostrophe Island (northern VL). Principal Component Analysis (PCA) identified the main trend of vegetation change, with a shift from lower to higher cover and a secondary trend of change associated with a gradient of water availability, consistent with an increase in water instead of snow. Redundancy analysis (RDA) identified the trend of change in soil chemistry with increases in pH, conductivity, anions and cations associated with the concomitant decrease in C, N, NO3, PO4. The RDA confirmed that soil changes were associated with a gradient of vegetation change (from low to high cover) as well as of water availability, as already indirectly outlined by the PCA. Field manipulation experiments carried out at five locations of the network between 73 degrees S and 77 degrees S, simulating increases of precipitation from snow or water additions didn't induce changes in soil pH, indicating that pulse events of snow accumulation or melting could not trigger persistent soil pH changes. These data allow hypothesize the occurrence of a main ecosystem change occurring at regional scale at Victoria Land. The slight air warming and its consequences on soil chemistry and vegetation, further highlight the sensitivity of the fragile Antarctic ecosystems to the consequences of even small changes in climate.}, language = {en} } @article{DoepperJagdhuberHoltgraveetal.2022, author = {D{\"o}pper, Veronika and Jagdhuber, Thomas and Holtgrave, Ann-Kathrin and Heistermann, Maik and Francke, Till and Kleinschmit, Birgit and F{\"o}rster, Michael}, title = {Following the cosmic-ray-neutron-sensing-based soil moisture under grassland and forest}, series = {Science of remote Sensing}, volume = {5}, journal = {Science of remote Sensing}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2666-0172}, doi = {10.1016/j.srs.2022.100056}, pages = {14}, year = {2022}, abstract = {Deriving soil moisture content (SMC) at the regional scale with different spatial and temporal land cover changes is still a challenge for active and passive remote sensing systems, often coped with machine learning methods. So far, the reference measurements of the data-driven approaches are usually based on point data, which entails a scale gap to the resolution of the remote sensing data. Cosmic Ray Neutron Sensing (CRNS) indirectly provides SMC estimates of a soil volume covering more than 1 ha and vertical depth up to 80 cm and is thus able to narrow this scale gap. So far, the CRNS-based SMC has only been used as validation source of remote sensing based SMC products. Its beneficial large sensing volume, especially in depth, has not been exploited yet. However, the sensing volume of the CRNS, which is changing with hydrological conditions, bears challenges for the comparison with remote sensing observations. This study, for the fist time, aims to understand the direct linkage of optical (Sentinel 2) and SAR (Sentinel 1) data with CRNS-based SMC. Thereby, the CRNS-based SMC is obtained by an experimental CRNS cluster that covers the high temporal and spatial SMC variability of an entire pre-alpine subcatchment. Using different Random Forest regressions, we analyze the potentials and limitations of both remote sensing sensors to follow the CRNS-based SMC signal. Our results show that it is possible to link the CRNS-based SMC signal with SAR and optical remote sensing observations via Random Forest modelling. We found that Sentinel 2 data is able to separate wet from dry periods with a R2 of 0.68. It is less affected by the changing soil volume that contributes to the CRNS-based SMC signal and it is able to assign a land cover specific SMC distribution. However, Sentinel 2 regression models are not accurate (R2 < 0.21) in mapping the CRNSbased SMC for the frequently mowed grassland areas of the study site. It requires soil type and topographical information to accurately follow the CRNS-based SMC signal with Random Forest regression. Sentinel 1 data instead is affected by the changing soil volume that contributes to the CRNS-based SMC signal. It has reasonable model performance (R2 = 0.34) when the CRNS data correspond to surface SMC. Also for Sentinel 1 the retrieval is impacted by the mowing activities at the test site. When separating the CRNS data set into dry and wet periods, soil properties and topography are the main drivers of SMC estimation. Sentinel 1 or Sentinel 2 data add the existing temporal variability to the regression models. The analysis underlines the need of combining optical and SAR observations (Sentinel 1, Sentinel 2) as well as soil property and topographical information to understand and follow the CRNS-based SMC signal for different hydrological conditions and land cover types.}, language = {en} } @article{BenZionDresen2022, author = {Ben-Zion, Yehuda and Dresen, Georg}, title = {A synthesis of fracture, friction and damage processes in earthquake rupture zones}, series = {Pure and applied geophysics}, volume = {179}, journal = {Pure and applied geophysics}, publisher = {Birkh{\"a}user}, address = {Basel}, issn = {0033-4553}, doi = {10.1007/s00024-022-03168-9}, pages = {4323 -- 4339}, year = {2022}, abstract = {We review properties and processes of earthquake rupture zones based on field studies, laboratory observations, theoretical models and simulations, with the goal of assessing the possible dominance of different processes in different parts of the rupture and validity of commonly used models. Rupture zones may be divided into front, intermediate, and tail regions that interact to different extents. The rupture front is dominated by fracturing and granulation processes and strong dilatation, producing faulting products that are reworked by subsequent sliding behind. The intermediate region sustains primarily frictional sliding with relatively high slip rates that produce appreciable stress transfer to the propagating front. The tail region further behind is characterized by low slip rates that effectively do not influence the propagating front, although it (and the intermediate region) can spawn small offspring rupture fronts. Wave-mediated stress transfer can also trigger failures ahead of the rupture front. Earthquake ruptures are often spatially discontinuous and intermittent with a hierarchy of asperity and segment sizes that radiate waves with different tensorial compositions and frequency bands. While different deformation processes dominating parts of the rupture zones can be treated effectively with existing constitutive relations, a more appropriate analysis of earthquake processes would require a model that combines aspects of fracture, damage-breakage, and frictional frameworks.}, language = {en} } @article{ZhouJomaaYangetal.2022, author = {Zhou, Xiangqian and Jomaa, Seifeddine and Yang, Xiaoqiang and Merz, Ralf and Wang, Yanping and Rode, Michael}, title = {Exploring the relations between sequential droughts and stream nitrogen dynamics in central Germany through catchment-scale mechanistic modelling}, series = {Journal of hydrology}, volume = {614}, journal = {Journal of hydrology}, number = {Part B}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2022.128615}, pages = {12}, year = {2022}, abstract = {Like many other regions in central Europe, Germany experienced sequential summer droughts from 2015 to 2018. As one of the environmental consequences, river nitrate concentrations have exhibited significant changes in many catchments. However, catchment nitrate responses to the changing weather conditions have not yet been mechanistically explored. Thus, a fully distributed, process-based catchment Nitrate model (mHM-Nitrate) was used to reveal the causal relations in the Bode catchment, of which river nitrate concentrations have experienced contrasting trends from upstream to downstream reaches. The model was evaluated using data from six gauging stations, reflecting different levels of runoff components and their associated nitrate-mixing from upstream to downstream. Results indicated that the mHM-Nitrate model reproduced dynamics of daily discharge and nitrate concentration well, with Nash-Sutcliffe Efficiency >= 0.73 for discharge and Kling-Gupta Efficiency >= 0.50 for nitrate concentration at most stations. Particularly, the spatially contrasting trends of nitrate con-centration were successfully captured by the model. The decrease of nitrate concentration in the lowland area in drought years (2015-2018) was presumably due to (1) limited terrestrial export loading (ca. 40 \% lower than that of normal years 2004-2014), and (2) increased in-stream retention efficiency (20 \% higher in summer within the whole river network). From a mechanistic modelling perspective, this study provided insights into spatially heterogeneous flow and nitrate dynamics and effects of sequential droughts, which shed light on water -quality responses to future climate change, as droughts are projected to be more frequent.}, language = {en} } @article{JiangSongBaueretal.2022, author = {Jiang, Feng and Song, Junwei and Bauer, Jonas and Gao, Linyu and Vallon, Magdalena and Gebhardt, Reiner and Leisner, Thomas and Norra, Stefan and Saathoff, Harald}, title = {Chromophores and chemical composition of brown carbon characterized at anurban kerbside by excitation-emission spectroscopy and mass spectrometry}, series = {Atmospheric chemistry and physics}, volume = {22}, journal = {Atmospheric chemistry and physics}, number = {22}, publisher = {EGU}, address = {Katlenburg-Lindau}, issn = {1680-7316}, doi = {10.5194/acp-22-14971-2022}, pages = {14971 -- 14986}, year = {2022}, abstract = {The optical properties, chemical composition, and potential chromophores of brown carbon (BrC) aerosol particles were studied during typical summertime and wintertime at a kerbside in downtown Karl-sruhe, a city in central Europe. The average absorption coefficient and mass absorption efficiency at 365 nm (Abs(365) and MAE(365)) of methanol-soluble BrC (MS-BrC) were lower in the summer period (1.6 +/- 0.5 Mm(-1), 0.5 +/- 0.2 m(2) g(-1)) than in the winter period (2.8 +/- 1.9 Mm(-1), 1.1 +/- 0.3 m(2) g(-1)). Using a parallel factor (PARAFAC) analysis to identify chromophores, two different groups of highly oxygenated humic-like substances (HO-HULIS) dominated in summer and contributed 96 +/- 6 \% of the total fluorescence intensity. In contrast, less-oxygenated HULIS (LO-HULIS) dominated the total fluorescence intensity in winter with 57 +/- 12 \%, followed by HO-HULIS with 31 +/- 18 \%. Positive matrix factorization (PMF) analysis of organic compounds detected in real time by an online aerosol mass spectrometer (AMS) led to five characteristic organic compound classes. The statistical analysis of PARAFAC components and PMF factors showed that LO-HULIS chromophores were most likely emitted from biomass burning in winter. HO-HULIS chromophores could be low-volatility oxy-genated organic aerosol from regional transport and oxidation of biogenic volatile organic compounds (VOCs) in summer. Five nitro-aromatic compounds (NACs) were identified by a chemical ionization mass spectrometer (C7H7O3N, C7H7O4N, C6H5O5N, C6H5O4N, and C6H5O3N), which contributed 0.03 +/- 0.01 \% to the total organic mass but can explain 0.3 +/- 0.1 \% of the total absorption of MS-BrC at 365 nm in winter. Furthermore, we identified 316 potential brown carbon molecules which accounted for 2.5 +/- 0.6 \% of the organic aerosol mass. Using an average mass absorption efficiency (MAE(365)) of 9.5 m(2)g(-1) for these compounds, we can es-timate their mean light absorption to be 1.2 +/- 0.2 Mm(-1), accounting for 32 +/- 15 \% of the total absorption of MS-BrC at 365 nm. This indicates that a small fraction of brown carbon molecules dominates the overall ab-sorption. The potential BrC molecules assigned to the LO-HULIS component had a higher average molecular weight (265 +/- 2 Da) and more nitrogen-containing molecules (62 +/- 1 \%) than the molecules assigned to the HOHULIS components. Our analysis shows that the LO-HULIS, with a high contribution of nitrogen-containing molecules originating from biomass burning, dominates aerosol fluorescence in winter, and HO-HULIS, with fewer nitrogen-containing molecules as low-volatility oxygenated organic aerosol from regional transport and oxidation of biogenic volatile organic compounds (VOC), dominates in summer.}, language = {en} } @article{PattonLunaRoeringetal.2023, author = {Patton, Annette I. and Luna, Lisa and Roering, Joshua J. and Jacobs, Aaron and Korup, Oliver and Mirus, Benjamin B.}, title = {Landslide initiation thresholds in data-sparse regions}, series = {Natural hazards and earth system sciences : NHESS}, volume = {23}, journal = {Natural hazards and earth system sciences : NHESS}, number = {10}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, issn = {1684-9981}, doi = {10.5194/nhess-23-3261-2023}, pages = {3261 -- 3284}, year = {2023}, abstract = {Probabilistic models to inform landslide early warning systems often rely on rainfall totals observed during past events with landslides. However, these models are generally developed for broad regions using large catalogs, with dozens, hundreds, or even thousands of landslide occurrences. This study evaluates strategies for training landslide forecasting models with a scanty record of landslide-triggering events, which is a typical limitation in remote, sparsely populated regions. We evaluate 136 statistical models trained on a precipitation dataset with five landslide-triggering precipitation events recorded near Sitka, Alaska, USA, as well as  6000 d of non-triggering rainfall (2002-2020). We also conduct extensive statistical evaluation for three primary purposes: (1) to select the best-fitting models, (2) to evaluate performance of the preferred models, and (3) to select and evaluate warning thresholds. We use Akaike, Bayesian, and leave-one-out information criteria to compare the 136 models, which are trained on different cumulative precipitation variables at time intervals ranging from 1 h to 2 weeks, using both frequentist and Bayesian methods to estimate the daily probability and intensity of potential landslide occurrence (logistic regression and Poisson regression). We evaluate the best-fit models using leave-one-out validation as well as by testing a subset of the data. Despite this sparse landslide inventory, we find that probabilistic models can effectively distinguish days with landslides from days without slide activity. Our statistical analyses show that 3 h precipitation totals are the best predictor of elevated landslide hazard, and adding antecedent precipitation (days to weeks) did not improve model performance. This relatively short timescale of precipitation combined with the limited role of antecedent conditions likely reflects the rapid draining of porous colluvial soils on the very steep hillslopes around Sitka. Although frequentist and Bayesian inferences produce similar estimates of landslide hazard, they do have different implications for use and interpretation: frequentist models are familiar and easy to implement, but Bayesian models capture the rare-events problem more explicitly and allow for better understanding of parameter uncertainty given the available data. We use the resulting estimates of daily landslide probability to establish two decision boundaries that define three levels of warning. With these decision boundaries, the frequentist logistic regression model incorporates National Weather Service quantitative precipitation forecasts into a real-time landslide early warning "dashboard" system (https://sitkalandslide.org/, last access: 9 October 2023). This dashboard provides accessible and data-driven situational awareness for community members and emergency managers.}, language = {en} } @article{PfauVehSchwanghart2023, author = {Pfau, Monika and Veh, Georg and Schwanghart, Wolfgang}, title = {Cast shadows reveal changes in glacier surface elevation}, series = {The Cryosphere : TC}, volume = {17}, journal = {The Cryosphere : TC}, number = {8}, publisher = {Copernicus}, address = {Katlenburg-Lindau}, issn = {1994-0424}, doi = {10.5194/tc-17-3535-2023}, pages = {3535 -- 3551}, year = {2023}, abstract = {Increased rates of glacier retreat and thinning need accurate local estimates of glacier elevation change to predict future changes in glacier runoff and their contribution to sea level rise. Glacier elevation change is typically derived from digital elevation models (DEMs) tied to surface change analysis from satellite imagery. Yet, the rugged topography in mountain regions can cast shadows onto glacier surfaces, making it difficult to detect local glacier elevation changes in remote areas. A rather untapped resource comprises precise, time-stamped metadata on the solar position and angle in satellite images. These data are useful for simulating shadows from a given DEM. Accordingly, any differences in shadow length between simulated and mapped shadows in satellite images could indicate a change in glacier elevation relative to the acquisition date of the DEM. We tested this hypothesis at five selected glaciers with long-term monitoring programmes. For each glacier, we projected cast shadows onto the glacier surface from freely available DEMs and compared simulated shadows to cast shadows mapped from ∼40 years of Landsat images. W validated the relative differences with geodetic measurements of glacier elevation change where these shadows occurred. We find that shadow-derived glacier elevation changes are consistent with independent photogrammetric and geodetic surveys in shaded areas. Accordingly, a shadow cast on Baltoro Glacier (the Karakoram, Pakistan) suggests no changes in elevation between 1987 and 2020, while shadows on Great Aletsch Glacier (Switzerland) point to negative thinning rates of about 1 m yr-1 in our sample. Our estimates of glacier elevation change are tied to occurrence of mountain shadows and may help complement field campaigns in regions that are difficult to access. This information can be vital to quantify possibly varying elevation-dependent changes in the accumulation or ablation zone of a given glacier. Shadow-based retrieval of glacier elevation changes hinges on the precision of the DEM as the geometry of ridges and peaks constrains the shadow that we cast on the glacier surface. Future generations of DEMs with higher resolution and accuracy will improve our method, enriching the toolbox for tracking historical glacier mass balances from satellite and aerial images.}, language = {en} } @article{JarajapuRathinasamyAgarwaletal.2022, author = {Jarajapu, Deva Charan and Rathinasamy, Maheswaran and Agarwal, Ankit and Bronstert, Axel}, title = {Design flood estimation using extreme Gradient Boosting-based on Bayesian optimization}, series = {Journal of hydrology}, volume = {613}, journal = {Journal of hydrology}, number = {Part A}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2022.128341}, pages = {16}, year = {2022}, abstract = {Regional Flood Frequency Analysis (RFFA) is one of the widely used approaches for estimating design floods in the ungauged basins. We developed an eXtreme Gradient Boost (XGB) machine learning model for RFFA and flood estimation. Our approach relies on developing a regression model between flood quantiles and the commonly available catchment descriptors. We used CAMELs data for 671 catchments from the USA to test the approach's efficacy. The results were compared with the traditional Multiple Linear Regression methods and Artificial Neural Networks. Results revealed that the XGB-based approach estimated design flood with the highest accuracy during training and validation with minor mean absolute error, root mean square error values, and percentage bias ranging from -10 to + 10. The importance of each catchment feature is visualized by three different approaches Gini Impurity, Permutation, and Dropout Loss Feature Ranking. We observed that the most dominating variables are rainfall intensity, slope, snow fraction, soil porosity, and temperature. It is observed that the importance of these variables is a function of the hydroclimatic regions and varies with space. In contrast, mean annual areal potential evapotranspiration, mean annual rainfall, fraction forest area, and soil conductivity have low significance in estimating design flood for an ungauged catchment. Indeed, the proposed XGB-based approach has broader applicability and replicability.}, language = {en} } @article{NguyenMerzHundechaetal.2021, author = {Nguyen, Viet-Dung and Merz, Bruno and Hundecha, Yeshewatesfa and Haberlandt, Uwe and Vorogushyn, Sergiy}, title = {Comprehensive evaluation of an improved large-scale multi-site weather generator for Germany}, series = {International journal of climatology : a journal of the Royal Meteorological Society}, volume = {41}, journal = {International journal of climatology : a journal of the Royal Meteorological Society}, number = {10}, publisher = {Wiley}, address = {Chichester [u.a.]}, issn = {0899-8418}, doi = {10.1002/joc.7107}, pages = {4933 -- 4956}, year = {2021}, abstract = {In this work, we present a comprehensive evaluation of a stochastic multi-site, multi-variate weather generator at the scale of entire Germany and parts of the neighbouring countries covering the major German river basins Elbe, Upper Danube, Rhine, Weser and Ems with a total area of approximately 580,000 km(2). The regional weather generator, which is based on a first-order multi-variate auto-regressive model, is setup using 53-year long daily observational data at 528 locations. The performance is evaluated by investigating the ability of the weather generator to replicate various important statistical properties of the observed variables including precipitation occurrence and dry/wet transition probabilities, mean daily and extreme precipitation, multi-day precipitation sums, spatial correlation structure, areal precipitation, mean daily and extreme temperature and solar radiation. We explore two marginal distributions for daily precipitation amount: mixed Gamma-Generalized Pareto and extended Generalized Pareto. Furthermore, we introduce a new procedure to estimate the spatial correlation matrix and model mean daily temperature and solar radiation. The extensive evaluation reveals that the weather generator is greatly capable of capturing most of the crucial properties of the weather variables, particularly of extreme precipitation at individual locations. Some deficiencies are detected in capturing spatial precipitation correlation structure that leads to an overestimation of areal precipitation extremes. Further improvement of the spatial correlation structure is envisaged for future research. The mixed marginal model found to outperform the extended Generalized Pareto in our case. The use of power transformation in combination with normal distribution significantly improves the performance for non-precipitation variables. The weather generator can be used to generate synthetic event footprints for large-scale trans-basin flood risk assessment.}, language = {en} } @article{HuangBorchardtRode2022, author = {Huang, Jingshui and Borchardt, Dietrich and Rode, Michael}, title = {How do inorganic nitrogen processing pathways change quantitatively at daily, seasonal, and multiannual scales in a large agricultural stream?}, series = {Hydrology and earth system sciences : HESS}, volume = {26}, journal = {Hydrology and earth system sciences : HESS}, number = {22}, publisher = {Copernicus Publ.}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-26-5817-2022}, pages = {5817 -- 5833}, year = {2022}, abstract = {Large agricultural streams receive excessive inputs of nitrogen. However, quantifying the role of these streams in nitrogen processing remains limited because continuous direct measurements of the interacting and highly time-varying nitrogen processing pathways in larger streams and rivers are very complex. Therefore, we employed a monitoring-driven modelling approach with high-frequency in situ data and the river water quality model Water Quality Analysis Simulation Program (WASP) 7.5.2 in the 27.4 km reach of the sixth-order agricultural stream called Lower Bode (central Germany) for a 5-year period (2014-2018). Paired high-frequency sensor data (15 min interval) of discharge, nitrate, dissolved oxygen, and chlorophyll a at upstream and downstream stations were used as model boundaries and for setting model constraints. The WASP model simulated 15 min intervals of discharge, nitrate, and dissolved oxygen with Nash-Sutcliffe efficiency values higher than 0.9 for calibration and validation, enabling the calculation of gross and net dissolved inorganic nitrogen uptake and pathway rates on a daily, seasonal, and multiannual scale. Results showed daily net uptake rate of dissolved inorganic nitrogen ranged from -17.4 to 553.9 mgNm(-2)d(-1). The highest daily net uptake could reach almost 30 \% of the total input loading, which occurred at extreme low flow in summer 2018. The growing season (spring and summer) accounted for 91 \% of the average net annual uptake of dissolved inorganic nitrogen in the measured period. In spring, both the DIN gross and net uptake were dominated by the phytoplankton uptake pathway. In summer, benthic algae assimilation dominated the gross uptake of dissolved inorganic nitrogen. Conversely, the reach became a net source of dissolved inorganic nitrogen with negative daily net uptake values in autumn and winter, mainly because the release from benthic algae surpassed uptake processes. Over the 5 years, average gross and net uptake rates of dissolved inorganic nitrogen were 124.1 and 56.8 mgNm(-2)d(-1), which accounted for only 2.7 \% and 1.2 \% of the total loadings in the Lower Bode, respectively. The 5-year average gross DIN uptake decreased from assimilation by benthic algae through assimilation by phytoplankton to denitrification. Our study highlights the value of combining river water quality modelling with high-frequency data to obtain a reliable budget of instream dissolved inorganic nitrogen processing which facilitates our ability to manage nitrogen in aquatic systems. This study provides a methodology that can be applied to any large stream to quantify nitrogen processing pathway dynamics and complete our understanding of nitrogen cycling.}, language = {en} } @article{RanaMalikOeztuerk2022, author = {Rana, Kamal and Malik, Nishant and {\"O}zt{\"u}rk, Ugur}, title = {Landsifier v1.0: a Python library to estimate likely triggers of mapped landslides}, series = {Natural hazards and earth system sciences}, volume = {22}, journal = {Natural hazards and earth system sciences}, number = {11}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-22-3751-2022}, pages = {3751 -- 3764}, year = {2022}, abstract = {Landslide hazard models aim at mitigating landslide impact by providing probabilistic forecasting, and the accuracy of these models hinges on landslide databases for model training and testing. Landslide databases at times lack information on the underlying triggering mechanism, making these inventories almost unusable in hazard models. We developed a Python-based unique library, Landsifier, that contains three different machine-Learning frameworks for assessing the likely triggering mechanisms of individual landslides or entire inventories based on landslide geometry. Two of these methods only use the 2D landslide planforms, and the third utilizes the 3D shape of landslides relying on an underlying digital elevation model (DEM). The base method extracts geometric properties of landslide polygons as a feature space for the shallow learner - random forest (RF). An alternative method relies on landslide planform images as an input for the deep learning algorithm - convolutional neural network (CNN). The last framework extracts topological properties of 3D landslides through topological data analysis (TDA) and then feeds these properties as a feature space to the random forest classifier. We tested all three interchangeable methods on several inventories with known triggers spread over the Japanese archipelago. To demonstrate the effectiveness of developed methods, we used two testing configurations. The first configuration merges all the available data for the k-fold cross-validation, whereas the second configuration excludes one inventory during the training phase to use as the sole testing inventory. Our geometric-feature-based method performs satisfactorily, with classification accuracies varying between 67 \% and 92 \%. We have introduced a more straightforward but data-intensive CNN alternative, as it inputs only landslide images without manual feature selection. CNN eases the scripting process without losing classification accuracy. Using topological features from 3D landslides (extracted through TDA) in the RF classifier improves classification accuracy by 12 \% on average. TDA also requires less training data. However, the landscape autocorrelation could easily bias TDA-based classification. Finally, we implemented the three methods on an inventory without any triggering information to showcase a real-world application.}, language = {en} } @article{CodecoWeisAndersen2022, author = {Code{\c{c}}o, Marta S. and Weis, Philipp and Andersen, Christine}, title = {Numerical modeling of structurally controlled ore formation in magmatic-hydrothermal systems}, series = {Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences}, volume = {23}, journal = {Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences}, number = {8}, publisher = {American Geophysical Union}, address = {Washington, DC}, issn = {1525-2027}, doi = {10.1029/2021GC010302}, pages = {20}, year = {2022}, abstract = {Faults and fractures can be permeable pathways for focused fluid flow in structurally controlled ore-forming hydrothermal systems. However, quantifying their role in fluid flow on the scale of several kilometers with numerical models typically requires high-resolution meshes. This study introduces a modified numerical representation of m-scale fault zones using lower-dimensional elements (here, one-dimensional [1D] elements in a 2D domain) to resolve structurally controlled fluid flow with coarser mesh resolutions and apply the method to magmatic-hydrothermal ore-forming systems. We modeled horizontal and vertical structure-controlled magmatic-hydrothermal deposits to understand the role of permeability and structure connectivity on ore deposition. The simulation results of vertically extended porphyry copper systems show that ore deposition can occur along permeable vertical structures where ascending, overpressured magmatic fluids are cooled by downflowing ambient fluids. Structure permeability and fault location control the distribution of ore grades. In highly permeable structures, the mineralization can span up to 3 km vertically, resulting in heat-pipe mechanisms that promote the ascent of a magmatic vapor phase to an overlying structurally controlled epithermal system. Simulations for the formation of subhorizontal vein-type deposits suggest that the major control on fluid flow and metal deposition along horizontal structures is the absence of vertical structures above the injection location but their presence at greater distances. Using a dynamic permeability model mimicking crack-seal mechanisms within the structures leads to a pulsating behavior of fracture-controlled hydrothermal systems and prevents the inflow of ambient fluids under overpressured conditions.}, language = {en} } @article{ApelVorogushynMerz2022, author = {Apel, Heiko and Vorogushyn, Sergiy and Merz, Bruno}, title = {Brief communication: impact forecasting could substantially improve the emergency management of deadly floods: case study July 2021 floods in Germany}, series = {Natural hazards and earth system sciences}, volume = {22}, journal = {Natural hazards and earth system sciences}, number = {9}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, issn = {1561-8633}, doi = {10.5194/nhess-22-3005-2022}, pages = {3005 -- 3014}, year = {2022}, abstract = {Floods affect more people than any other natural hazard; thus flood warning and disaster management are of utmost importance. However, the operational hydrological forecasts do not provide information about affected areas and impact but only discharge and water levels at gauges. We show that a simple hydrodynamic model operating with readily available data is able to provide highly localized information on the expected flood extent and impacts, with simulation times enabling operational flood warning. We demonstrate that such an impact forecast would have indicated the deadly potential of the 2021 flood in western Germany with sufficient lead time.}, language = {en} } @article{BillingThonickeSakschewskietal.2022, author = {Billing, Maik and Thonicke, Kirsten and Sakschewski, Boris and von Bloh, Werner and Walz, Ariane}, title = {Future tree survival in European forests depends on understorey tree diversity}, series = {Scientific reports}, volume = {12}, journal = {Scientific reports}, number = {1}, publisher = {Springer Nature}, address = {Berlin}, issn = {2045-2322}, doi = {10.1038/s41598-022-25319-7}, pages = {12}, year = {2022}, abstract = {Climate change heavily threatens forest ecosystems worldwide and there is urgent need to understand what controls tree survival and forests stability. There is evidence that biodiversity can enhance ecosystem stability (Loreau and de Mazancourt in Ecol Lett 16:106-115, 2013; McCann in Nature 405:228-233, 2000), however it remains largely unclear whether this also holds for climate change and what aspects of biodiversity might be most important. Here we apply machine learning to outputs of a flexible-trait Dynamic Global Vegetation Model to unravel the effects of enhanced functional tree trait diversity and its sub-components on climate-change resistance of temperate forests (http://www.pik-potsdam.de/similar to billing/video/Forest_Resistance_LPJmLFIT.mp4). We find that functional tree trait diversity enhances forest resistance. We explain this with 1. stronger complementarity effects (similar to 25\% importance) especially improving the survival of trees in the understorey of up to +16.8\% (+/- 1.6\%) and 2. environmental and competitive filtering of trees better adapted to future climate (40-87\% importance). We conclude that forests containing functionally diverse trees better resist and adapt to future conditions. In this context, we especially highlight the role of functionally diverse understorey trees as they provide the fundament for better survival of young trees and filtering of resistant tree individuals in the future.}, language = {en} } @article{LunaKorup2022, author = {Luna, Lisa and Korup, Oliver}, title = {Seasonal landslide activity lags annual precipitation pattern in the Pacific Northwest}, series = {Geophysical research letters}, volume = {49}, journal = {Geophysical research letters}, number = {18}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {0094-8276}, doi = {10.1029/2022GL098506}, pages = {11}, year = {2022}, abstract = {Seasonal variations in landslide activity remain understudied compared to recent advances in landslide early warning at hourly to daily timescales. Here, we learn the seasonal pattern of monthly landslide activity in the Pacific Northwest from five heterogeneous landslide inventories with differing spatial and temporal coverage and reporting protocols combined in a Bayesian multi-level model. We find that landslide activity is distinctly seasonal, with credible increases in landslide intensity, inter-annual variability, and probability marking the onset of the landslide season in November. Peaks in landslide probability in January and intensity in February lag the annual peak in mean monthly precipitation and landslide activity is more variable in winter than in summer, when landslides are rare. For a given monthly rainfall, landslide intensity at the season peak in February is up to 10 times higher than at the onset in November, underlining the importance of antecedent seasonal hillslope conditions.}, language = {en} } @article{SteinMukkavilliWagener2022, author = {Stein, Lina and Mukkavilli, Surya Karthik and Wagener, Thorsten}, title = {Lifelines for a drowning science - improving findability and synthesis of hydrologic publications}, series = {Hydrological processes}, volume = {36}, journal = {Hydrological processes}, number = {11}, publisher = {Wiley}, address = {New York, NY}, issn = {0885-6087}, doi = {10.1002/hyp.14742}, pages = {7}, year = {2022}, abstract = {Increasing publication numbers make it difficult to keep up with knowledge evolution in a science like hydrology. Here we give recommendations to authors and journals for writing future-proof articles that contribute to knowledge accumulation and synthesis.}, language = {en} } @phdthesis{Bryant2024, author = {Bryant, Seth}, title = {Aggregation and disaggregation in flood risk models}, doi = {10.25932/publishup-65095}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-650952}, school = {Universit{\"a}t Potsdam}, pages = {ix, 116}, year = {2024}, abstract = {Floods continue to be the leading cause of economic damages and fatalities among natural disasters worldwide. As future climate and exposure changes are projected to intensify these damages, the need for more accurate and scalable flood risk models is rising. Over the past decade, macro-scale flood risk models have evolved from initial proof-of-concepts to indispensable tools for decision-making at global-, nationaland, increasingly, the local-level. This progress has been propelled by the advent of high-performance computing and the availability of global, space-based datasets. However, despite such advancements, these models are rarely validated and consistently fall short of the accuracy achieved by high-resolution local models. While capabilities have improved, significant gaps persist in understanding the behaviours of such macro-scale models, particularly their tendency to overestimate risk. This dissertation aims to address such gaps by examining the scale transfers inherent in the construction and application of coarse macroscale models. To achieve this, four studies are presented that, collectively, address exposure, hazard, and vulnerability components of risk affected by upscaling or downscaling. The first study focuses on a type of downscaling where coarse flood hazard inundation grids are enhanced to a finer resolution. While such inundation downscaling has been employed in numerous global model chains, ours is the first study to focus specifically on this component, providing an evaluation of the state of the art and a novel algorithm. Findings demonstrate that our novel algorithm is eight times faster than existing methods, offers a slight improvement in accuracy, and generates more physically coherent flood maps in hydraulically challenging regions. When applied to a case study, the algorithm generated a 4m resolution inundation map from 30m hydrodynamic model outputs in 33 s, a 60-fold improvement in runtime with a 25\% increase in RMSE compared with direct hydrodynamic modelling. All evaluated downscaling algorithms yielded better accuracy than the coarse hydrodynamic model when compared to observations, demonstrating similar limits of coarse hydrodynamic models reported by others. The substitution of downscaling into flood risk model chains, in place of high-resolution modelling, can drastically improve the lead time of impactbased forecasts and the efficiency of hazard map production. With downscaling, local regions could obtain high resolution local inundation maps by post-processing a global model without the need for expensive modelling or expertise. The second study focuses on hazard aggregation and its implications for exposure, investigating implicit aggregations commonly used to intersect hazard grids with coarse exposure models. This research introduces a novel spatial classification framework to understand the effects of rescaling flood hazard grids to a coarser resolution. The study derives closed-form analytical solutions for the location and direction of bias from flood grid aggregation, showing that bias will always be present in regions near the edge of inundation. For example, inundation area will be positively biased when water depth grids are aggregated, while volume will be negatively biased when water elevation grids are aggregated. Extending the analysis to effects of hazard aggregation on building exposure, this study shows that exposure in regions at the edge of inundation are an order of magnitude more sensitive to aggregation errors than hazard alone. Among the two aggregation routines considered, averaging water surface elevation grids better preserved flood depths at buildings than averaging of water depth grids. The study provides the first mathematical proof and generalizeable treatment of flood hazard grid aggregation, demonstrating important mechanisms to help flood risk modellers understand and control model behaviour. The final two studies focus on the aggregation of vulnerability models or flood damage functions, investigating the practice of applying per-asset functions to aggregate exposure models. Both studies extend Jensen's inequality, a well-known 1906 mathematical proof, to demonstrate how the aggregation of flood damage functions leads to bias. Applying Jensen's proof in this new context, results show that typically concave flood damage functions will introduce a positive bias (overestimation) when aggregated. This behaviour was further investigated with a simulation experiment including 2 million buildings in Germany, four global flood hazard simulations and three aggregation scenarios. The results show that positive aggregation bias is not distributed evenly in space, meaning some regions identified as "hot spots of risk" in assessments may in fact just be hot spots of aggregation bias. This study provides the first application of Jensen's inequality to explain the overestimates reported elsewhere and advice for modellers to minimize such artifacts. In total, this dissertation investigates the complex ways aggregation and disaggregation influence the behaviour of risk models, focusing on the scale-transfers underpinning macro-scale flood risk assessments. Extending a key finding of the flood hazard literature to the broader context of flood risk, this dissertation concludes that all else equal, coarse models overestimate risk. This dissertation goes beyond previous studies by providing mathematical proofs for how and where such bias emerges in aggregation routines, offering a mechanistic explanation for coarse model overestimates. It shows that this bias is spatially heterogeneous, necessitating a deep understanding of how rescaling may bias models to effectively reduce or communicate uncertainties. Further, the dissertation offers specific recommendations to help modellers minimize scale transfers in problematic regions. In conclusion, I argue that such aggregation errors are epistemic, stemming from choices in model structure, and therefore hold greater potential and impetus for study and mitigation. This deeper understanding of uncertainties is essential for improving macro-scale flood risk models and their effectiveness in equitable, holistic, and sustainable flood management.}, language = {en} } @article{HeydenNatho2022, author = {Heyden, Janika and Natho, Stephanie}, title = {Assessing floodplain management in Germany - a case study on nationwide research and actions}, series = {Sustainability}, volume = {14}, journal = {Sustainability}, number = {17}, publisher = {MDPI}, address = {Basel}, issn = {2071-1050}, doi = {10.3390/su141710610}, pages = {18}, year = {2022}, abstract = {After a long history of floodplain degradation and substantial losses of inundation areas over the last decades, a rethinking of floodplain management has taken place in Germany. Floodplains are now acknowledged as important areas for both biodiversity and society. This transformation has been significantly supported by nationwide research activities. A systematic assessment of the current floodplain management is still lacking. We therefore developed a scheme to assess floodplain management through the steps of identification, analysis, implementation, and evaluation. Reviewing the data and literature on nationwide floodplain-related research and activities, we defined key elements of floodplain management for Germany. We concluded that research activities already follow a strategic nationwide approach of identifying and analyzing floodplains. Progress in implementation is slow, however, and potentials are far from being reached. Nevertheless, new and unique initiatives enable Germany to stay on the long-term path of giving rivers more space and improving floodplain conditions.}, language = {en} } @article{CescaMalebranLopezCominoetal.2021, author = {Cesca, Simone and Malebran, Carla Valenzuela and Lopez-Comino, Jose Angel and Davis, Timothy and Tassara, Carlos and Oncken, Onno and Dahm, Torsten}, title = {The 2014 Juan Fernandez microplate earthquake doublet}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {801}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2021.228720}, pages = {13}, year = {2021}, abstract = {On October 9, 2014, a Mw 7.1-6.7 seismic doublet occurred at the Juan Fernandez microplate, close to the triple junction with Pacific and Nazca plates. The Mw 7.1 earthquake is the largest earthquake ever to have been recorded in the region. Its thrust focal mechanism is also unusual for the region, although the northern part of the microplate is expected to undergo compression. The region is remote and seismological data is limited to a seismic station at similar to 600 km distance on Easter Island and teleseismic observations for the largest events. We use a combination of advanced seismological techniques to overcome the lack of local data and resolve earthquake source parameters for the doublet and its aftershock sequence, being able to reconstruct the chronology of the sequence and the geometry of affected fault segments. Our results depict a complex seismic sequence characterized by the interplay of thrust and strike-slip earthquakes along different structures, including a second, reversed strike slip-thrust seismic doublet in November 2014. Seismicity occurred within the microplate and only in the late part of the sequence migrated northward, towards the microplate boundary. The first largest doublet, whose rupture kinematic is well explained by stress changes imparted by the first subevent on the second one, may have activated unmapped E-W and NE-SW faults or an internal curved pseudofault, attributed to the longterm rotation of the microplate. Few large, thrust earthquakes are observed within the sequence, taking place in the vicinity of mapped compressional ridges. We suggest that compressional stresses in the northern part of the microplate and at its boundary are partially accommodated aseismically. However, the occasional occurrence of large, impulsive thrust earthquakes, with a considerable tsunamigenic potential, poses a relevant hazard for islands in the South Pacific region.}, language = {en} } @misc{SchoenfeldtPanekWinocuretal.2020, author = {Schoenfeldt, Elisabeth and Panek, Tomas and Winocur, Diego and Silhan, Karel and Korup, Oliver}, title = {Corrigendum to: postglacial Patagonian mass movement}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {373}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2020.107471}, pages = {1}, year = {2020}, language = {en} } @phdthesis{Reuss2024, author = {Reuß, Maximilian}, title = {Laborexperimente, {\"U}berwachung und Simulation einer reaktiven Wand zur Abreinigung von eisen- und sulfathaltigen Bergbauw{\"a}ssern bei sauren und neutralen pH-Bedingungen}, doi = {10.25932/publishup-64856}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-648564}, school = {Universit{\"a}t Potsdam}, pages = {XIV, 126, LXI}, year = {2024}, abstract = {In dieser Arbeit wurde eine reaktive Wand in einem kleinskaligen Laborma\ss stab (L{\"a}nge~=~40\,cm) entwickelt, die Eisen- und Sulfatbelastungen aus sauren Minenabw{\"a}ssern (engl. \textit{acid mine drainage} (AMD)) mit einer Effizienz von bis zu 30.2 bzw. 24.2\,\\% {\"u}ber einen Zeitraum von 146~Tagen (50\,pv) abreinigen k{\"o}nnen sollte. Als reaktives Material wurde eine Mischung aus Gartenkompost, Buchenholz, Kokosnussschale und Calciumcarbonat verwendet. Die Zugabebedingungen waren eine Eisenkonzentration von 1000\,mg/L, eine Sulfatkonzentration von 3000\,mg/L und ein pH-Wert von 6.2. Unterschiede in der Materialzusammensetzung ergaben keine gr{\"o}\ss eren {\"A}nderungen in der Sanierungseffizienz von Eisen- und Sulfatbelastungen (12.0 -- 15.4\,\\% bzw. 7.0 -- 10.1\,\\%) {\"u}ber einen Untersuchungszeitraum von 108~Tagen (41 -- 57\,pv). Der wichtigste Einflussfaktor auf die Abreinigungsleistung von Sulfat- und Eisenbelastungen war die Verweilzeit der AMD-L{\"o}sung im reaktiven Material. Diese kann durch eine Verringerung des Durchflusses oder eine Erh{\"o}hung der L{\"a}nge der reaktiven Wand (engl. \textit{Permeable Reactive Barrier} (PRB)) erh{\"o}ht werden. Ein halbierter Durchfluss erh{\"o}hte die Sanierungseffizienzen von Eisen und Sulfat auf 23.4 bzw. 32.7\,\\%. Weiterhin stieg die Sanierungseffizienz der Eisenbelastungen auf 24.2\,\\% bei einer Erh{\"o}hung der Sulfatzugabekonzentration auf 6000\,mg/L. Saure Startbedingungen (pH~=~2.2) konnten, durch das Calciumcarbonat im reaktiven Material, {\"u}ber einen Zeitraum von 47~Tagen (24\,pv) neutralisiert werden. Durch die Neutralisierung der sauren Startbedingungen wurde Calciumcarbonat in der \gls{prb} verbraucht und Calcium-Ionen freigesetzt, die die Sulfatsanierungseffizienz erh{\"o}ht haben (24.9\,\\%). Aufgrund einer Vergr{\"o}\ss erung der \gls{prb} in Breite und Tiefe und einer 2D-Parameterbestimmung konnten Randl{\"a}ufigkeiten beobachtet werden, ohne deren Einfluss sich die Sanierungseffizienz f{\"u}r Eisen- und Sulfatbelastungen erh{\"o}ht (30.2 bzw. 24.2\,\\%). \par Zur \textit{in-situ} {\"U}berwachung der \gls{prb} wurden optische Sensoren verwendet, um den pH-Wert, die Sauerstoffkonzentration und die Temperatur zu ermitteln. Es wurden, nach dem Ort und der Zeit aufgel{\"o}st, stabile Sauerstoffkonzentrationen und pH-Verl{\"a}ufe detektiert. Auch die Temperatur konnte nach dem Ort aufgel{\"o}st ermittelt werden. Damit zeigte diese Arbeit, dass optische Sensoren zur {\"U}berwachung der Stabilit{\"a}t einer \gls{prb} f{\"u}r die Reinigung von \gls{amd} verwendet werden k{\"o}nnen. \par Mit dem Simulationsprogramm MIN3P wurde eine Simulation erstellt, die die entwickelte PRB darstellt. Die Simulation kann die erhaltenen Laborergebnisse gut wiedergeben. Anschlie\ss end wurde eine simulierte \gls{prb} bei unterschiedlichen Filtergeschwindigkeiten ((4.0 -- 23.5)~\$\cdot~\mathrm{10^{-7}}\$\,m/s) und L{\"a}ngen der PRB (25 -- 400\,cm) untersucht. Es wurden Zusammenh{\"a}nge der untersuchten Parameter mit der Sanierungseffizienz von Eisen- und Sulfatbelastungen ermittelt. Diese Zusammenh{\"a}nge k{\"o}nnen verwendet werden, um die ben{\"o}tigte Verweilzeit der AMD-L{\"o}sung in einem zuk{\"u}nftigen PRB-System, die f{\"u}r die maximal m{\"o}gliche Sanierungsleistung notwendig ist, zu berechnen.}, language = {de} } @article{BuergerHeistermann2023, author = {B{\"u}rger, Gerd and Heistermann, Maik}, title = {Shallow and deep learning of extreme rainfall events from convective atmospheres}, series = {Natural hazards and earth system sciences : NHESS}, volume = {23}, journal = {Natural hazards and earth system sciences : NHESS}, number = {9}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, issn = {1561-8633}, doi = {10.5194/nhess-23-3065-2023}, pages = {3065 -- 3077}, year = {2023}, abstract = {Our subject is a new catalogue of radar-based heavy rainfall events (CatRaRE) over Germany and how it relates to the concurrent atmospheric circulation. We classify daily ERA5 fields of convective indices according to CatRaRE, using an array of 13 statistical methods, consisting of 4 conventional ("shallow") and 9 more recent deep machine learning (DL) algorithms; the classifiers are then applied to corresponding fields of simulated present and future atmospheres from the Coordinated Regional Climate Downscaling Experiment (CORDEX) project. The inherent uncertainty of the DL results from the stochastic nature of their optimization is addressed by employing an ensemble approach using 20 runs for each network. The shallow random forest method performs best with an equitable threat score (ETS) around 0.52, followed by the DL networks ALL-CNN and ResNet with an ETS near 0.48. Their success can be understood as a result of conceptual simplicity and parametric parsimony, which obviously best fits the relatively simple classification task. It is found that, on summer days, CatRaRE convective atmospheres over Germany occur with a probability of about 0.5. This probability is projected to increase, regardless of method, both in ERA5-reanalyzed and CORDEX-simulated atmospheres: for the historical period we find a centennial increase of about 0.2 and for the future period one of slightly below 0.1.}, language = {en} } @article{ShikangalahMapaniMapaureetal.2021, author = {Shikangalah, Rosemary and Mapani, Benjamin and Mapaure, Isaac and Herzschuh, Ulrike}, title = {Responsiveness of Dichrostachys cinerea to seasonal variations in temperature and rainfall in central Namibia}, series = {Flora}, volume = {286}, journal = {Flora}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0367-2530}, doi = {10.1016/j.flora.2021.151974}, pages = {7}, year = {2021}, abstract = {Woody plants provide natural archives of climatic variation which can be investigated by applying dendroclimatological methods. Such studies are limited in Southern Africa but have great potential of improving our understanding of past climates and plant functional adaptations in the region. This study therefore investigated the responsiveness of Dichrostachys cinerea to seasonal variations in temperature and rainfall at two sites in central Namibia, Waterberg and Kuzikus. Dichrostachys cinerea is one of the encroacher species thriving well in Namibia. A moving correlation and response function analysis were used to test its responsiveness to seasonal climatic variations over time. Dichrostachys cinerea growth rings showed relationships to late summer warming, lasting up to half of the rainy season. The results also revealed that past temperatures had been fluctuating and their influence on growth rings had been intensifying over the years, but to varying extents between the two sites. Temperature was a more important determinant of ring growth at the drier site (Kuzikus), while rainfall was more important at the wetter site (Waterberg). Growth ring responsiveness to rainfall was not immediate but showed a rather lagged pattern. We conclude that D. cinerea differentially responds to variations in rainfall and temperature across short climatic gradients. This study showed that the species, due to its somewhat wide ecological amplitude, has great potential for dendroclimatological studies in tropical regions.}, language = {en} } @phdthesis{Bubeck2024, author = {Bubeck, Philip}, title = {Flood impacts, behavioural responses of individuals, and integrated risk management}, school = {Universit{\"a}t Potsdam}, pages = {328}, year = {2024}, language = {en} } @article{RomeroBarbosaCoelhoScheiffeleetal.2021, author = {Romero Barbosa, Lu{\´i}s and Coelho, Victor Hugo R. and Scheiffele, Lena and Baroni, Gabriele and Ramos Filho, Geraldo M. and Montenegro, Suzana M. G. L. and Das Neves Almeida, Cristiano and Oswald, Sascha}, title = {Dynamic groundwater recharge simulations based on cosmic-ray neutron sensing in a tropical wet experimental basin}, series = {Vadose zone journal : VZJ : advancing critical zone science}, volume = {20}, journal = {Vadose zone journal : VZJ : advancing critical zone science}, number = {4}, publisher = {Wiley}, address = {Hoboken}, issn = {1539-1663}, doi = {10.1002/vzj2.20145}, pages = {22}, year = {2021}, abstract = {Although cosmic-ray neutron sensing (CRNS) is probably the most promising noninvasive proximal soil moisture measurement technique at the field scale, its application for hydrological simulations remains underexplored in the literature so far. This study assessed the use of CRNS to inversely calibrate soil hydraulic parameters at the intermediate field scale to simulate the groundwater recharge rates at a daily timescale. The study was conducted for two contrasting hydrological years at the Guaraira experimental basin, Brazil, a 5.84-km(2), a tropical wet and rather flat landscape covered by secondary Atlantic forest. As a consequence of the low altitude and proximity to the equator low neutron count rates could be expected, reducing the precision of CRNS while constituting unexplored and challenging conditions for CRNS applications. Inverse calibration for groundwater recharge rates was used based on CRNS or point-scale soil moisture data. The CRNS-derived retention curve and saturated hydraulic conductivity were consistent with the literature and locally performed slug tests. Simulated groundwater recharge rates ranged from 60 to 470 mm yr(-1), corresponding to 5 and 29\% of rainfall, and correlated well with estimates based on water table fluctuations. In contrast, the estimated results based on inversive point-scale datasets were not in alignment with measured water table fluctuations. The better performance of CRNS-based estimations of field-scale hydrological variables, especially groundwater recharge, demonstrated its clear advantages over traditional invasive point-scale techniques. Finally, the study proved the ability of CRNS as practicable in low altitude, tropical wet areas, thus encouraging its adoption for water resources monitoring and management.}, language = {en} } @phdthesis{Rasche2024, author = {Rasche, Daniel}, title = {Cosmic-ray neutron sensing for the estimation of soil moisture}, doi = {10.25932/publishup-63646}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-636465}, school = {Universit{\"a}t Potsdam}, pages = {xvi, 194}, year = {2024}, abstract = {Water stored in the unsaturated soil as soil moisture is a key component of the hydrological cycle influencing numerous hydrological processes including hydrometeorological extremes. Soil moisture influences flood generation processes and during droughts when precipitation is absent, it provides plant with transpirable water, thereby sustaining plant growth and survival in agriculture and natural ecosystems. Soil moisture stored in deeper soil layers e.g. below 100 cm is of particular importance for providing plant transpirable water during dry periods. Not being directly connected to the atmosphere and located outside soil layers with the highest root densities, water in these layers is less susceptible to be rapidly evaporated and transpired. Instead, it provides longer-term soil water storage increasing the drought tolerance of plants and ecosystems. Given the importance of soil moisture in the context of hydro-meteorological extremes in a warming climate, its monitoring is part of official national adaption strategies to a changing climate. Yet, soil moisture is highly variable in time and space which challenges its monitoring on spatio-temporal scales relevant for flood and drought risk modelling and forecasting. Introduced over a decade ago, Cosmic-Ray Neutron Sensing (CRNS) is a noninvasive geophysical method that allows for the estimation of soil moisture at relevant spatio-temporal scales of several hectares at a high, subdaily temporal resolution. CRNS relies on the detection of secondary neutrons above the soil surface which are produced from high-energy cosmic-ray particles in the atmosphere and the ground. Neutrons in a specific epithermal energy range are sensitive to the amount of hydrogen present in the surroundings of the CRNS neutron detector. Due to same mass as the hydrogen nucleus, neutrons lose kinetic energy upon collision and are subsequently absorbed when reaching low, thermal energies. A higher amount of hydrogen therefore leads to fewer neutrons being detected per unit time. Assuming that the largest amount of hydrogen is stored in most terrestrial ecosystems as soil moisture, changes of soil moisture can be estimated through an inverse relationship with observed neutron intensities. Although important scientific advancements have been made to improve the methodological framework of CRNS, several open challenges remain, of which some are addressed in the scope of this thesis. These include the influence of atmospheric variables such as air pressure and absolute air humidity, as well as, the impact of variations in incoming primary cosmic-ray intensity on observed epithermal and thermal neutron signals and their correction. Recently introduced advanced neutron-to-soil moisture transfer functions are expected to improve CRNS-derived soil moisture estimates, but potential improvements need to be investigated at study sites with differing environmental conditions. Sites with strongly heterogeneous, patchy soil moisture distributions challenge existing transfer functions and further research is required to assess the impact of, and correction of derived soil moisture estimates under heterogeneous site conditions. Despite its capability of measuring representative averages of soil moisture at the field scale, CRNS lacks an integration depth below the first few decimetres of the soil. Given the importance of soil moisture also in deeper soil layers, increasing the observational window of CRNS through modelling approaches or in situ measurements is of high importance for hydrological monitoring applications. By addressing these challenges, this thesis aids to closing knowledge gaps and finding answers to some of the open questions in CRNS research. Influences of different environmental variables are quantified, correction approaches are being tested and developed. Neutron-to-soil moisture transfer functions are evaluated and approaches to reduce effects of heterogeneous soil moisture distributions are presented. Lastly, soil moisture estimates from larger soil depths are derived from CRNS through modified, simple modelling approaches and in situ estimates by using CRNS as a downhole technique. Thereby, this thesis does not only illustrate the potential of new, yet undiscovered applications of CRNS in future but also opens a new field of CRNS research. Consequently, this thesis advances the methodological framework of CRNS for above-ground and downhole applications. Although the necessity of further research in order to fully exploit the potential of CRNS needs to be emphasised, this thesis contributes to current hydrological research and not least to advancing hydrological monitoring approaches being of utmost importance in context of intensifying hydro-meteorological extremes in a changing climate.}, language = {en} } @article{SchulteMeucciStoofLeichsenringetal.2022, author = {Schulte, Luise and Meucci, Stefano and Stoof-Leichsenring, Kathleen R. and Heitkam, Tony and Schmidt, Nicola and von Hippel, Barbara and Andreev, Andrei A. and Diekmann, Bernhard and Biskaborn, Boris and Wagner, Bernd and Melles, Martin and Pestryakova, Lyudmila A. and Alsos, Inger G. and Clarke, Charlotte and Krutovsky, Konstantin and Herzschuh, Ulrike}, title = {Larix species range dynamics in Siberia since the Last Glacial captured from sedimentary ancient DNA}, series = {Communications biology}, volume = {5}, journal = {Communications biology}, number = {1}, publisher = {Springer Nature}, address = {London}, issn = {2399-3642}, doi = {10.1038/s42003-022-03455-0}, pages = {11}, year = {2022}, abstract = {Climate change is expected to cause major shifts in boreal forests which are in vast areas of Siberia dominated by two species of the deciduous needle tree larch (Larix). The species differ markedly in their ecosystem functions, thus shifts in their respective ranges are of global relevance. However, drivers of species distribution are not well understood, in part because paleoecological data at species level are lacking. This study tracks Larix species distribution in time and space using target enrichment on sedimentary ancient DNA extracts from eight lakes across Siberia. We discovered that Larix sibirica, presently dominating in western Siberia, likely migrated to its northern distribution area only in the Holocene at around 10,000 years before present (ka BP), and had a much wider eastern distribution around 33 ka BP. Samples dated to the Last Glacial Maximum (around 21 ka BP), consistently show genotypes of L. gmelinii. Our results suggest climate as a strong determinant of species distribution in Larix and provide temporal and spatial data for species projection in a changing climate. Using ancient sedimentary DNA from up to 50 kya, dramatic distributional shifts are documented in two dominant boreal larch species, likely guided by environmental changes suggesting climate as a strong determinant of species distribution.}, language = {en} } @article{DunkerBoydDurkaetal.2022, author = {Dunker, Susanne and Boyd, Matthew and Durka, Walter and Erler, Silvio and Harpole, W. Stanley and Henning, Silvia and Herzschuh, Ulrike and Hornick, Thomas and Knight, Tiffany and Lips, Stefan and M{\"a}der, Patrick and Švara, Elena Motivans and Mozarowski, Steven and Rakosy, Demetra and R{\"o}mermann, Christine and Schmitt-Jansen, Mechthild and Stoof-Leichsenring, Kathleen and Stratmann, Frank and Treudler, Regina and Virtanen, Risto and Wendt-Potthoff, Katrin and Wilhelm, Christian}, title = {The potential of multispectral imaging flow cytometry for environmental monitoring}, series = {Cytometry part A}, volume = {101}, journal = {Cytometry part A}, number = {9}, publisher = {Wiley}, address = {Hoboken}, issn = {1552-4922}, doi = {10.1002/cyto.a.24658}, pages = {782 -- 799}, year = {2022}, abstract = {Environmental monitoring involves the quantification of microscopic cells and particles such as algae, plant cells, pollen, or fungal spores. Traditional methods using conventional microscopy require expert knowledge, are time-intensive and not well-suited for automated high throughput. Multispectral imaging flow cytometry (MIFC) allows measurement of up to 5000 particles per second from a fluid suspension and can simultaneously capture up to 12 images of every single particle for brightfield and different spectral ranges, with up to 60x magnification. The high throughput of MIFC has high potential for increasing the amount and accuracy of environmental monitoring, such as for plant-pollinator interactions, fossil samples, air, water or food quality that currently rely on manual microscopic methods. Automated recognition of particles and cells is also possible, when MIFC is combined with deep-learning computational techniques. Furthermore, various fluorescence dyes can be used to stain specific parts of the cell to highlight physiological and chemical features including: vitality of pollen or algae, allergen content of individual pollen, surface chemical composition (carbohydrate coating) of cells, DNA- or enzyme-activity staining. Here, we outline the great potential for MIFC in environmental research for a variety of research fields and focal organisms. In addition, we provide best practice recommendations.}, language = {en} } @article{CaoChenTianetal.2022, author = {Cao, Xianyong and Chen, Jianhui and Tian, Fang and Xu, Qinghai and Herzschuh, Ulrike and Telford, Richard and Huang, Xiaozhong and Zheng, Zhuo and Shen, Caiming and Li, Wenjia}, title = {Long-distance modern analogues bias results of pollen-based precipitation reconstructions}, series = {Science bulletin}, volume = {67}, journal = {Science bulletin}, number = {11}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2095-9273}, doi = {10.1016/j.scib.2022.01.003}, pages = {1115 -- 1117}, year = {2022}, language = {en} } @article{NitzscheKleebergHoffmannetal.2022, author = {Nitzsche, Kai Nils and Kleeberg, Andreas and Hoffmann, Carsten and Merz, Christoph and Premke, Katrin and Gessler, Arthur and Sommer, Michael and Kayler, Zachary E.}, title = {Kettle holes reflect the biogeochemical characteristics of their catchment area and the intensity of the element-specific input}, series = {Journal of soils and sediments : protection, risk assessment and remediation}, volume = {22}, journal = {Journal of soils and sediments : protection, risk assessment and remediation}, number = {3}, publisher = {Springer}, address = {Heidelberg}, issn = {1439-0108}, doi = {10.1007/s11368-022-03145-8}, pages = {994 -- 1009}, year = {2022}, abstract = {Purpose Kettle holes are small inland water bodies known to be dominated by terrigenous material; however, the processes and structures that drive the enrichment and depletion of specific geochemical elements in the water column and kettle hole sediment remain unclear. We hypothesized that the mobile elements (Ca, Fe, K, P) behave different from each other in their transport, intermediate soil retention, and final accumulation in the kettle hole sediment. Methods Topsoils from transects spanning topographic positions from erosional to depositional areas, sediment cores, shallow groundwater, and kettle hole water of two glacial kettle holes in NE Germany (Rittgarten (RG) and Kraatz (KR)) were collected. The Fe, Ca, K, and total P (TP) concentrations were quantified and additionally the major anions in shallow groundwater and kettle hole water. The element-specific mobilization, relocation, and, finally, accumulation in the sediment were investigated by enrichment factors. Furthermore, a piper diagram was used to estimate groundwater flow directions and pond-internal processes. Results At KR only, the upper 10 cm of the kettle hole sediment reflected the relative element composition of the eroded terrestrial soils. The sediment from both kettle holes was enriched in Ca, Fe, K, and P compared to topsoils, indicating several possible processes including the input of clay and silt sized particles enriched in these elements, fertilizer input, and pond-internal processes including biogenic calcite and hydroxyapatite precipitation, Fe-P binding (KR), FeSx formation (RG), and elemental fixation and deposition via floating macrophytes (RG). High Ca concentrations in the kettle hole water indicated a high input of Ca from shallow groundwater inflow, while Ca precipitation in the kettle hole water led to lower Ca concentration in groundwater outflow. Conclusions The considerable element losses in the surrounding soils and the inputs into the kettle holes should be addressed by comprehensive soil and water protection measures, i.e., avoiding tillage, fertilizing conservatively, and creating buffer zones.}, language = {en} } @article{HeistermannFranckeScheiffeleetal.2023, author = {Heistermann, Maik and Francke, Till and Scheiffele, Lena and Petrova, Katya Dimitrova and Budach, Christian and Schr{\"o}n, Martin and Trost, Benjamin and Rasche, Daniel and G{\"u}ntner, Andreas and Doepper, Veronika and F{\"o}rster, Michael and K{\"o}hli, Markus and Angermann, Lisa and Antonoglou, Nikolaos and Zude, Manuela and Oswald, Sascha}, title = {Three years of soil moisture observations by a dense cosmic-ray neutron sensing cluster at an agricultural research site in north-east Germany}, series = {Earth system science data : ESSD}, volume = {15}, journal = {Earth system science data : ESSD}, number = {7}, publisher = {Copernics Publications}, address = {Katlenburg-Lindau}, issn = {1866-3508}, doi = {10.5194/essd-15-3243-2023}, pages = {3243 -- 3262}, year = {2023}, abstract = {Cosmic-ray neutron sensing (CRNS) allows for the estimation of root-zone soil water content (SWC) at the scale of several hectares. In this paper, we present the data recorded by a dense CRNS network operated from 2019 to 2022 at an agricultural research site in Marquardt, Germany - the first multi-year CRNS cluster. Consisting, at its core, of eight permanently installed CRNS sensors, the cluster was supplemented by a wealth of complementary measurements: data from seven additional temporary CRNS sensors, partly co-located with the permanent ones; 27 SWC profiles (mostly permanent); two groundwater observation wells; meteorological records; and Global Navigation Satellite System reflectometry (GNSS-R). Complementary to these continuous measurements, numerous campaign-based activities provided data by mobile CRNS roving, hyperspectral im-agery via UASs, intensive manual sampling of soil properties (SWC, bulk density, organic matter, texture, soil hydraulic properties), and observations of biomass and snow (cover, depth, and density). The unique temporal coverage of 3 years entails a broad spectrum of hydro-meteorological conditions, including exceptional drought periods and extreme rainfall but also episodes of snow coverage, as well as a dedicated irrigation experiment. Apart from serving to advance CRNS-related retrieval methods, this data set is expected to be useful for vari-ous disciplines, for example, soil and groundwater hydrology, agriculture, or remote sensing. Hence, we show exemplary features of the data set in order to highlight the potential for such subsequent studies. The data are available at doi.org/10.23728/b2share.551095325d74431881185fba1eb09c95 (Heistermann et al., 2022b).}, language = {en} } @article{CaoTianHerzschuhetal.2022, author = {Cao, Xianyong and Tian, Fang and Herzschuh, Ulrike and Ni, Jian and Xu, Qinghai and Li, Wenjia and Zhang, Yanrong and Luo, Mingyu and Chen, Fahu}, title = {Human activities have reduced plant diversity in eastern China over the last two millennia}, series = {Global change biology}, volume = {28}, journal = {Global change biology}, number = {16}, publisher = {Wiley}, address = {Hoboken}, issn = {1354-1013}, doi = {10.1111/gcb.16274}, pages = {4962 -- 4976}, year = {2022}, abstract = {Understanding the history and regional singularities of human impact on vegetation is key to developing strategies for sustainable ecosystem management. In this study, fossil and modern pollen datasets from China are employed to investigate temporal changes in pollen composition, analogue quality, and pollen diversity during the Holocene. Anthropogenic disturbance and vegetation's responses are also assessed. Results reveal that pollen assemblages from non-forest communities fail to provide evidence of human impact for the western part of China (annual precipitation less than 400 mm and/or elevation more than 3000 m.a.s.l.), as inferred from the stable quality of modern analogues, principal components, and diversity of species and communities throughout the Holocene. For the eastern part of China, the proportion of fossil pollen spectra with good modern analogues increases from ca. 50\% to ca. 80\% during the last 2 millennia, indicating an enhanced intensity of anthropogenic disturbance on vegetation. This disturbance has caused the pollen spectra to become taxonomically less diverse over space (reduced abundances of arboreal taxa and increased abundances of herbaceous taxa), highlighting a reduced south-north differentiation and divergence from past vegetation between regions in the eastern part of China. We recommend that care is taken in eastern China when basing the development of ecosystem management strategies on vegetation changes in the region during the last 2000 years, since humans have significantly disturbed the vegetation during this period.}, language = {en} } @article{RodriguesRodriguesRaabeetal.2023, author = {Rodrigues, Glauber Pontes and Rodrigues, {\´I}talo Sampaio and Raabe, Armin and Holstein, Peter and De Araujo, Jos{\`e} Carlos}, title = {Direct measurement of open-water evaporation}, series = {Hydrological sciences journal}, volume = {68}, journal = {Hydrological sciences journal}, number = {3}, publisher = {Taylor \& Francis}, address = {Abingdon, Oxon}, issn = {0262-6667}, doi = {10.1080/02626667.2022.2157278}, pages = {379 -- 394}, year = {2023}, abstract = {This study investigates the sensitivity and uncertainty of evaporation assessment in a tropical reservoir in northeastern Brazil. For this purpose, four approaches were used: Penman, a Dalton-modified equation, a pressure meter and a novel acoustic sensor. The main objective is to evaluate whether sensors can be employed to adequately assess lake evaporation. The sensors were installed in floating pans and the equations are based on variables collected from a raft. The wind-inducted waves in the reservoir often disturbed the measurements using both pressure (uncertainty of +/- 0.6 mm) and acoustic (uncertainty of +/- 0.1 mm) sensors, causing flaws and affecting continuous monitoring. The modified Dalton model, based on data collected with a floating station, estimated values over three-hour courses of evaporation similar to those measured by the pressure meter. These findings are important contributions to an accurate monitoring of water losses through evaporation and reservoir operation, particularly in dry regions.}, language = {en} } @article{TianQinZhangetal.2022, author = {Tian, Fang and Qin, Wen and Zhang, Ran and Herzschuh, Ulrike and Ni, Jian and Zhang, Chengjun and Mischke, Steffen and Cao, Xianyong}, title = {Palynological evidence for the temporal stability of the plant community in the Yellow River Source Area over the last 7,400 years}, series = {Vegetation history and archaeobotany}, volume = {31}, journal = {Vegetation history and archaeobotany}, number = {6}, publisher = {Springer}, address = {New York}, issn = {0939-6314}, doi = {10.1007/s00334-022-00870-5}, pages = {549 -- 558}, year = {2022}, abstract = {The terrestrial ecosystem in the Yellow River Source Area (YRSA) is sensitive to climate change and human impacts, although past vegetation change and the degree of human disturbance are still largely unknown. A 170-cm-long sediment core covering the last 7,400 years was collected from Lake Xingxinghai (XXH) in the YRSA. Pollen, together with a series of other environmental proxies (including grain size, total organic carbon (TOC) and carbonate content), were analysed to explore past vegetation and environmental changes for the YRSA. Dominant and common pollen components-Cyperaceae, Poaceae, Artemisia, Chenopodiaceae and Asteraceae-are stable throughout the last 7,400 years. Slight vegetation change is inferred from an increasing trend of Cyperaceae and decreasing trend of Poaceae, suggesting that alpine steppe was replaced by alpine meadow at ca. 3.5 ka cal bp. The vegetation transformation indicates a generally wetter climate during the middle and late Holocene, which is supported by increased amounts of TOC and Pediastrum (representing high water-level) and is consistent with previous past climate records from the north-eastern Tibetan Plateau. Our results find no evidence of human impact on the regional vegetation surrounding XXH, hence we conclude the vegetation change likely reflects the regional climate signal.}, language = {en} } @article{WalchSinghSoreideetal.2022, author = {Walch, Daniela M. R. and Singh, Rakesh K. and Soreide, Janne E. and Lantuit, Hugues and Poste, Amanda}, title = {Spatio-temporal variability of suspended particulate matter in a high-arctic estuary (Adventfjorden, Svalbard) using sentinel-2 time-series}, series = {Remote sensing}, volume = {14}, journal = {Remote sensing}, number = {13}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs14133123}, pages = {22}, year = {2022}, abstract = {Arctic coasts, which feature land-ocean transport of freshwater, sediments, and other terrestrial material, are impacted by climate change, including increased temperatures, melting glaciers, changes in precipitation and runoff. These trends are assumed to affect productivity in fjordic estuaries. However, the spatial extent and temporal variation of the freshwater-driven darkening of fjords remain unresolved. The present study illustrates the spatio-temporal variability of suspended particulate matter (SPM) in the Adventfjorden estuary, Svalbard, using in-situ field campaigns and ocean colour remote sensing (OCRS) via high-resolution Sentinel-2 imagery. To compute SPM concentration (C-SPMsat), a semi-analytical algorithm was regionally calibrated using local in-situ data, which improved the accuracy of satellite-derived SPM concentration by similar to 20\% (MRD). Analysis of SPM concentration for two consecutive years (2019, 2020) revealed strong seasonality of SPM in Adventfjorden. Highest estimated SPM concentrations and river plume extent (\% of fjord with C-SPMsat > 30 mg L-1) occurred during June, July, and August. Concurrently, we observed a strong relationship between river plume extent and average air temperature over the 24 h prior to the observation (R-2 = 0.69). Considering predicted changes to environmental conditions in the Arctic region, this study highlights the importance of the rapidly changing environmental parameters and the significance of remote sensing in analysing fluxes in light attenuating particles, especially in the coastal Arctic Ocean.}, language = {en} } @article{AndreevRaschkeBiskabornetal.2021, author = {Andreev, Andrei and Raschke, Elena and Biskaborn, Boris and Vyse, Stuart Andrew and Courtin, J{\´e}r{\´e}my and B{\"o}hmer, Thomas and Stoof-Leichsenring, Kathleen R. and Kruse, Stefan and Pestryakova, Luidmila Agafyevna and Herzschuh, Ulrike}, title = {Late Pleistocene to Holocene vegetation and climate changes in northwestern Chukotka (Far East Russia) deduced from lakes Ilirney and Rauchuagytgyn pollen records}, series = {Boreas : an international journal of quaternary research}, volume = {50}, journal = {Boreas : an international journal of quaternary research}, number = {3}, publisher = {Wiley-Blackwell}, address = {Oxford [u.a.]}, issn = {0300-9483}, doi = {10.1111/bor.12521}, pages = {652 -- 670}, year = {2021}, abstract = {This paper presents two new pollen records and quantitative climate reconstructions from northern Chukotka documenting environmental changes over the last 27.9 ka. Open tundra- and steppe-like habitats dominated between 27.9 and 18.7 cal. ka BP. Betula and Alnus shrubs might have grown in sheltered microhabitats but disappeared after 18.7 cal. ka BP. Although the climate was rather harsh, local herb-dominated communities supported herbivores as is evident by the presence of coprophilous spores in the sediments. The increase in Salix and Cyperaceae similar to 16.1 cal. ka BP suggests climate amelioration. Shrub Betula appeared similar to 15.9 cal. ka BP, and became dominant after similar to 15.52 cal. ka BP, whilst typical steppe communities drastically reduced. Very high presence of Botryococcus in the Lateglacial sediments reflects widespread shallow habitats, probably due to lake level increase. Shrub Alnus became common after similar to 13 cal. ka BP reflecting further climate amelioration. Simultaneously, herb communities gradually decreased in the vegetation reaching a minimum similar to 11.8 cal. ka BP. A gradual decrease of algae remains suggests a reduction of shallow-water habitats. Shrubby and graminoid tundra was dominant similar to 11.8-11.1 cal. ka BP, later Salix stands significantly decreased. The forest-tundra ecotone established in the Early Holocene, shortly after 11.1 cal. ka BP. Low contents of green algae in the Early Holocene sediments likely reflect deeper aquatic conditions. The most favourable climate conditions were between similar to 10.6 and 7 cal. ka BP. Vegetation became similar to the modern after similar to 7 cal. ka BP but Pinus pumila came to the Ilirney area at about 1.2 cal. ka BP. It is important to emphasize that the study area provided refugia for Betula and Alnus during MIS 2. It is also notable that our records do not reflect evidence of Younger Dryas cooling, which is inconsistent with some regional environmental records but in good accordance with some others.}, language = {en} } @article{ZhangCaoXuetal.2022, author = {Zhang, Naimeng and Cao, Xianyong and Xu, Qinghai and Huang, Xiaozhong and Herzschuh, Ulrike and Shen, Zhongwei and Peng, Wei and Liu, Sisi and Wu, Duo and Wang, Jian and Xia, Huan and Zhang, Dongju and Chen, Fahu}, title = {Vegetation change and human-environment interactions in the Qinghai Lake Basin, northeastern Tibetan Plateau, since the last deglaciation}, series = {Catena}, volume = {210}, journal = {Catena}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0341-8162}, doi = {10.1016/j.catena.2021.105892}, pages = {14}, year = {2022}, abstract = {The nature of the interaction between prehistoric humans and their environment, especially the vegetation, has long been of interest. The Qinghai Lake Basin in North China is well-suited to exploring the interactions between prehistoric humans and vegetation in the Tibetan Plateau, because of the comparatively dense distribution of archaeological sites and the ecologically fragile environment. Previous pollen studies of Qinghai Lake have enabled a detailed reconstruction of the regional vegetation, but they have provided relatively little information on vegetation change within the Qinghai Lake watershed. To address the issue we conducted a pollen-based vegetation reconstruction for an archaeological site (YWY), located on the southern shore of Qinghai Lake. We used high temporal-resolution pollen records from the YWY site and from Qinghai Lake, spanning the interval since the last deglaciation (15.3 kyr BP to the present) to quantitatively reconstruct changes in the local and regional vegetation using Landscape Reconstruction Algorithm models. The results show that, since the late glacial, spruce forest grew at high altitudes in the surrounding mountains, while the lakeshore environment was occupied mainly by shrub-steppe. From the lateglacial to the middle Holocene, coniferous woodland began to expand downslope and reached the YWY site at 7.1 kyr BP. The living environment of the local small groups of Paleolithic-Epipaleolithic humans (during 15.3-13.1 kyr BP and 9-6.4 kyr BP) changed from shrub-steppe to coniferous forest-steppe. The pollen record shows no evidence of pronounced changes in the vegetation community corresponding to human activity. However, based on a comparison of the local and regional vegetation reconstructions, low values of biodiversity and a significant increase in two indicators of vegetation degradation, Chenopodiaceae and Rosaceae, suggest that prehistoric hunters-gatherers likely disturbed the local vegetation during 9.0-6.4 kyr BP. Our findings are a preliminary attempt to study human-environment interactions at Paleolithic-Epipaleolithic sites in the region, and they contribute to ongoing environmental archaeology research in the Tibetan Plateau.}, language = {en} } @article{DietzeBellOeztuerketal.2022, author = {Dietze, Michael and Bell, Rainer and {\"O}zt{\"u}rk, Ugur and Cook, Kristen L. and Andermann, Christoff and Beer, Alexander R. and Damm, Bodo and Lucia, Ana and Fauer, Felix S. and Nissen, Katrin M. and Sieg, Tobias and Thieken, Annegret H.}, title = {More than heavy rain turning into fast-flowing water - a landscape perspective on the 2021 Eifel floods}, series = {Natural hazards and earth system sciences}, volume = {22}, journal = {Natural hazards and earth system sciences}, number = {6}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-22-1845-2022}, pages = {1845 -- 1856}, year = {2022}, abstract = {Rapidly evolving floods are rare but powerful drivers of landscape reorganisation that have severe and long-lasting impacts on both the functions of a landscape's subsystems and the affected society. The July 2021 flood that particularly hit several river catchments of the Eifel region in western Germany and Belgium was a drastic example. While media and scientists highlighted the meteorological and hydrological aspects of this flood, it was not just the rising water levels in the main valleys that posed a hazard, caused damage, and drove environmental reorganisation. Instead, the concurrent coupling of landscape elements and the wood, sediment, and debris carried by the fast-flowing water made this flood so devastating and difficult to predict. Because more intense floods are able to interact with more landscape components, they at times reveal rare non-linear feedbacks, which may be hidden during smaller events due to their high thresholds of initiation. Here, we briefly review the boundary conditions of the 14-15 July 2021 flood and discuss the emerging features that made this event different from previous floods. We identify hillslope processes, aspects of debris mobilisation, the legacy of sustained human land use, and emerging process connections and feedbacks as critical non-hydrological dimensions of the flood. With this landscape scale perspective, we develop requirements for improved future event anticipation, mitigation, and fundamental system understanding.}, language = {en} } @article{YadavSenMaoetal.2022, author = {Yadav, Anshul and Sen, Sumit and Mao, Luca and Schwanghart, Wolfgang}, title = {Evaluation of flow resistance equations for high gradient rivers using geometric standard deviation of bed material}, series = {Journal of hydrology}, volume = {605}, journal = {Journal of hydrology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2021.127292}, pages = {16}, year = {2022}, abstract = {A dataset of 2184 field measurements reported in the literature was used to evaluate the predictive capability of eight conventional flow resistance equations to predict the mean flow velocity in gravel-bed rivers. The results reveal considerable disagreement with the observed flow velocities for relative submergence less than 4 and for the non-uniformity of the bed material greater than 7.5 for all the equations. However, the predictions made using the Smart and Jaggi (1983), Ferguson (2007), and Rickenmann and Recking (2011) equations were closer to the observed values. Furthermore, bedload sediment transport also reduces the predictive capability of the equations considered in this study except for the Recking et al. (2008) equation, which was developed consid- ering active bedload transport. The performance of flow resistance equations improves when corrected by considering the geometric standard deviation of the bed material. Here we present an empirical approach using the whole dataset and its subsets for accounting for the additional energy losses occurring due to the wake vortices, spill losses, and free surface instabilities occurring due to the protrusions from the bed. The results obtained using the validation dataset shows the importance and usefulness of this approach to account for the additional energy losses, especially for the Strickler (1923) and Keulegan (1938) equations.}, language = {en} } @article{AndreevNazarovaLenzetal.2022, author = {Andreev, Andrei and Nazarova, Larisa B. and Lenz, Marlene M. and B{\"o}hmer, Thomas and Syrykh, Ludmila and Wagner, Bernd and Melles, Martin and Pestryakova, Luidmila A. and Herzschuh, Ulrike}, title = {Late Quaternary paleoenvironmental reconstructions from sediments of Lake Emanda (Verkhoyansk Mountains, East Siberia)}, series = {Journal of quaternary science : JQS}, volume = {37}, journal = {Journal of quaternary science : JQS}, number = {5}, publisher = {Wiley}, address = {New York, NY [u.a.]}, issn = {0267-8179}, doi = {10.1002/jqs.3419}, pages = {884 -- 899}, year = {2022}, abstract = {Continuous pollen and chironomid records from Lake Emanda (65 degrees 17'N, 135 degrees 45'E) provide new insights into the Late Quaternary environmental history of the Yana Highlands (Yakutia). Larch forest with shrubs (alders, pines, birches) dominated during the deposition of the lowermost sediments suggesting its Early Weichselian [Marine Isotope Stage (MIS) 5] age. Pollen- and chironomid-based climate reconstructions suggest July temperatures (T-July) slightly lower than modern. Gradually increasing amounts of herb pollen and cold stenotherm chironomid head capsules reflect cooler and drier environments, probably during the termination of MIS 5. T-July dropped to 8 degrees C. Mostly treeless vegetation is reconstructed during MIS 3. Tundra and steppe communities dominated during MIS 2. Shrubs became common after similar to 14.5 ka BP but herb-dominated habitats remained until the onset of the Holocene. Larch forests with shrub alder and dwarf birch dominated after the Holocene onset, ca. 11.7 ka BP. Decreasing amounts of shrub pollen during the Lateglacial are assigned to the Older Dryas and Younger Dryas with T-July similar to 7.5 degrees C. T-July increased up to 13 degrees C. Shrub stone pine was present after similar to 7.5 ka BP. The vegetation has been similar to modern since ca. 5.8 ka BP. Chironomid diversity and concentration in the sediments increased towards the present day, indicating the development of richer hydrobiological communities in response to the Holocene thermal maximum.}, language = {en} } @article{RabbiShantKarmakaretal.2021, author = {Rabbi, Sifat E. and Shant, Reza and Karmakar, Sourav and Habib, Azhar and Kropp, J{\"u}rgen}, title = {Regional mapping of climate variability index and identifying}, series = {Environment, development and sustainability : a multidisciplinary approach to the theory and practice of sustainable development}, volume = {23}, journal = {Environment, development and sustainability : a multidisciplinary approach to the theory and practice of sustainable development}, number = {7}, publisher = {Springer}, address = {Dordrecht}, issn = {1387-585X}, doi = {10.1007/s10668-020-01104-2}, pages = {11050 -- 11066}, year = {2021}, abstract = {Studies conducted in Bangladesh so far did not unequivocally identify the modus operandi of local farmers to perceive and experience the climate variability at a national scale. Hence, this study aims to decipher local farmer's perception on climate variability for the last 10 years, by constructing climate variability index (CVI). Additionally, this study demystified the socio-economic determinants for influencing farmer perception regarding climate variability as well as its impact on their livelihoods. The study was designed on a cross-sectional data through a country-wide primary survey of 16,053 households who were largely dependent on agriculture. A weighted index was constructed for mapping the regional climate variability using model-builder programming in ArcGIS. Also, a multivariable probit model was employed to identify the factors influencing farmers' perception and resulting impact of climate variability on their livelihoods. According to local farmer's perception, the CVI mapping identified that Bangladesh experienced variegated climatic variability since last 10 years. However, local farmer's perception varied with different socio-economic factors like gender, education, farmer's category, credit, monthly income and access to media. Moreover, landless, small and medium farm holders were more aware of the local climate variability and eventually, they also experienced the higher influence of climate variability on their livelihoods. Since an effective mapping of regional climate variability is a sine qua non to devise region specific policies, this study will facilitate the government to determine its priorities, formulate efficacious strategies and thereby help to adapt with future climate-induced risks and vulnerabilities.}, language = {en} } @misc{DietzeOeztuerk2021, author = {Dietze, Michael and {\"O}zt{\"u}rk, Ugur}, title = {A flood of disaster response challenges}, series = {Science}, volume = {373}, journal = {Science}, number = {6561}, publisher = {American Association for the Advancement of Science}, address = {Washington}, issn = {0036-8075}, doi = {10.1126/science.abm0617}, pages = {1317 -- 1318}, year = {2021}, language = {en} } @article{BryantMcGrathBoudreault2022, author = {Bryant, Seth and McGrath, Heather and Boudreault, Mathieu}, title = {Gridded flood depth estimates from satellite-derived inundations}, series = {Natural hazards and earth system sciences}, volume = {22}, journal = {Natural hazards and earth system sciences}, number = {4}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, issn = {1561-8633}, doi = {10.5194/nhess-22-1437-2022}, pages = {1437 -- 1450}, year = {2022}, abstract = {Canada's RADARSAT missions improve the potential to study past flood events; however, existing tools to derive flood depths from this remote-sensing data do not correct for errors, leading to poor estimates. To provide more accurate gridded depth estimates of historical flooding, a new tool is proposed that integrates Height Above Nearest Drainage and Cost Allocation algorithms. This tool is tested against two trusted, hydraulically derived, gridded depths of recent floods in Canada. This validation shows the proposed tool outperforms existing tools and can provide more accurate estimates from minimal data without the need for complex physics-based models or expert judgement. With improvements in remote-sensing data, the tool proposed here can provide flood researchers and emergency managers accurate depths in near-real time.}, language = {en} } @article{RanaOeztuerkMalik2021, author = {Rana, Kamal and {\"O}zt{\"u}rk, Ugur and Malik, Nishant}, title = {Landslide geometry reveals its trigger}, series = {Geophysical research letters : GRL / American Geophysical Union}, volume = {48}, journal = {Geophysical research letters : GRL / American Geophysical Union}, number = {4}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1029/2020GL090848}, pages = {8}, year = {2021}, abstract = {Electronic databases of landslides seldom include the triggering mechanisms, rendering these inventories unusable for landslide hazard modeling. We present a method for classifying the triggering mechanisms of landslides in existing inventories, thus, allowing these inventories to aid in landslide hazard modeling corresponding to the correct event chain. Our method uses various geometric characteristics of landslides as the feature space for the machine-learning classifier random forest, resulting in accurate and robust classifications of landslide triggers. We applied the method to six landslide inventories spread over the Japanese archipelago in several different tests and training configurations to demonstrate the effectiveness of our approach. We achieved mean accuracy ranging from 67\% to 92\%. We also provide an illustrative example of a real-world usage scenario for our method using an additional inventory with unknown ground truth. Furthermore, our feature importance analysis indicates that landslides having identical trigger mechanisms exhibit similar geometric properties.}, language = {en} } @article{StoofLeichsenringHuangLiuetal.2022, author = {Stoof-Leichsenring, Kathleen R. and Huang, Sichao and Liu, Sisi and Jia, Weihan and Li, Kai and Liu, Xingqi and Pestryakova, Luidmila A. and Herzschuh, Ulrike}, title = {Sedimentary DNA identifies modern and past macrophyte diversity and its environmental drivers in high-latitude and high-elevation lakes in Siberia and China}, series = {Limnology and oceanography}, volume = {67}, journal = {Limnology and oceanography}, number = {5}, publisher = {Wiley-Blackwell}, address = {Oxford [u.a.]}, issn = {0024-3590}, doi = {10.1002/lno.12061}, pages = {1126 -- 1141}, year = {2022}, abstract = {Arctic and alpine aquatic ecosystems are changing rapidly under recent global warming, threatening water resources by diminishing trophic status and changing biotic composition. Macrophytes play a key role in the ecology of freshwaters and we need to improve our understanding of long-term macrophytes diversity and environmental change so far limited by the sporadic presence of macrofossils in sediments. In our study, we applied metabarcoding using the trnL P6 loop marker to retrieve macrophyte richness and composition from 179 surface-sediment samples from arctic Siberian and alpine Chinese lakes and three representative lake cores. The surface-sediment dataset suggests that macrophyte richness and composition are mostly affected by temperature and conductivity, with highest richness when mean July temperatures are higher than 12 degrees C and conductivity ranges between 40 and 400 mu S cm(-1). Compositional turnover during the Late Pleistocene/Holocene is minor in Siberian cores and characterized by a less rich, but stable emergent macrophyte community. Richness decreases during the Last Glacial Maximum and rises during wetter and warmer climate in the Late-glacial and Mid-Holocene. In contrast, we detect a pronounced change from emergent to submerged taxa at 14 ka in the Tibetan alpine core, which can be explained by increasing temperature and conductivity due to glacial runoff and evaporation. Our study provides evidence for the suitability of the trnL marker to recover modern and past macrophyte diversity and its applicability for the response of macrophyte diversity to lake-hydrochemical and climate variability predicting contrasting macrophyte changes in arctic and alpine lakes under intensified warming and human impact.}, language = {en} }