@incollection{LueckBalderjahnKammetal.2000, author = {L{\"u}ck, Erika and Balderjahn, Ingo and Kamm, Birgit and Greil, Holle and Wallschl{\"a}ger, Hans-Dieter and Jessel, Beate and B{\"o}ckmann, Christine and Oberh{\"a}nsli, Roland and Soyez, Konrad and Schmeer, Ernst and Blumenstein, Oswald and Berndt, Klaus-Peter and Edeling, Thomas and Friedrich, Sabine and Kaden, Klaus and Scheller, Frieder W. and Petersen, Hans-Georg and Asche, Hartmut and Bronstert, Axel and Giest, Hartmut and Gaedke, Ursula and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Jeltsch, Florian and J{\"a}nkel, Ralph and Gzik, Axel and Bork, Hans-Rudolf and Bork, Hans-Rudolf}, title = {Umweltforschung f{\"u}r das Land Brandenburg : Arbeitsgruppen und Professuren}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-3797}, publisher = {Universit{\"a}t Potsdam}, year = {2000}, language = {de} } @misc{KormannBronstertFranckeetal.2017, author = {Kormann, Christoph and Bronstert, Axel and Francke, Till and Recknagel, Thomas and Gr{\"a}ff, Thomas}, title = {Model-Based attribution of high-resolution streamflow trends in two alpine basins of Western Austria}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400641}, pages = {21}, year = {2017}, abstract = {Several trend studies have shown that hydrological conditions are changing considerably in the Alpine region. However, the reasons for these changes are only partially understood and trend analyses alone are not able to shed much light. Hydrological modelling is one possible way to identify the trend drivers, i.e., to attribute the detected streamflow trends, given that the model captures all important processes causing the trends. We modelled the hydrological conditions for two alpine catchments in western Austria (a large, mostly lower-altitude catchment with wide valley plains and a nested high-altitude, glaciated headwater catchment) with the distributed, physically-oriented WaSiM-ETH model, which includes a dynamical glacier module. The model was calibrated in a transient mode, i.e., not only on several standard goodness measures and glacier extents, but also in such a way that the simulated streamflow trends fit with the observed ones during the investigation period 1980 to 2007. With this approach, it was possible to separate streamflow components, identify the trends of flow components, and study their relation to trends in atmospheric variables. In addition to trends in annual averages, highly resolved trends for each Julian day were derived, since they proved powerful in an earlier, data-based attribution study. We were able to show that annual and highly resolved trends can be modelled sufficiently well. The results provide a holistic, year-round picture of the drivers of alpine streamflow changes: Higher-altitude catchments are strongly affected by earlier firn melt and snowmelt in spring and increased ice melt throughout the ablation season. Changes in lower-altitude areas are mostly caused by earlier and lower snowmelt volumes. All highly resolved trends in streamflow and its components show an explicit similarity to the local temperature trends. Finally, results indicate that evapotranspiration has been increasing in the lower altitudes during the study period.}, language = {en} } @article{VormoorLawrenceHeistermannetal.2015, author = {Vormoor, Klaus Josef and Lawrence, D. and Heistermann, Maik and Bronstert, Axel}, title = {Climate change impacts on the seasonality and generation processes of floods}, series = {Hydrology and earth system sciences : HESS}, volume = {19}, journal = {Hydrology and earth system sciences : HESS}, number = {2}, publisher = {Copernicus Publications}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-19-913-2015}, pages = {913 -- 931}, year = {2015}, abstract = {Climate change is likely to impact the seasonality and generation processes of floods in the Nordic countries, which has direct implications for flood risk assessment, design flood estimation, and hydropower production management. Using a multi-model/multi-parameter approach to simulate daily discharge for a reference (1961-1990) and a future (2071-2099) period, we analysed the projected changes in flood seasonality and generation processes in six catchments with mixed snowmelt/rainfall regimes under the current climate in Norway. The multi-model/multi-parameter ensemble consists of (i) eight combinations of global and regional climate models, (ii) two methods for adjusting the climate model output to the catchment scale, and (iii) one conceptual hydrological model with 25 calibrated parameter sets. Results indicate that autumn/winter events become more frequent in all catchments considered, which leads to an intensification of the current autumn/winter flood regime for the coastal catchments, a reduction of the dominance of spring/summer flood regimes in a high-mountain catchment, and a possible systematic shift in the current flood regimes from spring/summer to autumn/winter in the two catchments located in northern and south-eastern Norway. The changes in flood regimes result from increasing event magnitudes or frequencies, or a combination of both during autumn and winter. Changes towards more dominant autumn/winter events correspond to an increasing relevance of rainfall as a flood generating process (FGP) which is most pronounced in those catchments with the largest shifts in flood seasonality. Here, rainfall replaces snowmelt as the dominant FGP primarily due to increasing temperature.We further analysed the ensemble components in contributing to overall uncertainty in the projected changes and found that the climate projections and the methods for downscaling or bias correction tend to be the largest contributors. The relative role of hydrological parameter uncertainty, however, is highest for those catchments showing the largest changes in flood seasonality, which confirms the lack of robustness in hydrological model parameterization for simulations under transient hydrometeorological conditions.}, language = {en} } @article{DeAraujoGuentnerBronstert2006, author = {De Araujo, Jos{\`e} Carlos and G{\"u}ntner, Andreas and Bronstert, Axel}, title = {Loss of reservoir volume by sediment deposition and its impact on water availability in semiarid Brazil}, issn = {0262-6667}, doi = {10.1623/hysj.51.1.157}, year = {2006}, abstract = {A methodology is presented to assess the impact of reservoir silting oil water availability for semiarid environments, applied to seven representative watersheds in the state of Ceara, Brazil. Water yield is computed using stochastic modelling for several reliability levels and water yield reduction is quantified for the focus areas. The yield-volume elasticity concept, which indicates the relative yield reduction in terms of relative storage capacity of the reservoirs, is presented and applied. Results chow that storage capacity was reduced by 0.2\% year(-1) due to silting, that the risk of water shortage almost doubled in less than 50 years for the most critical reservoir, and that reduction of storage capacity had three times more impact oil yield reduction than the increase in evaporation. Average 90\% reliable yield-volume elasticity was 0.8, which means that the global water yield (Q(90)) in Ceara is expected to diminish yearly by 388 L s(-1) due to reservoir silting}, language = {en} } @book{BronstertCarreraKabatetal.2005, author = {Bronstert, Axel and Carrera, Jesus and Kabat, Pavel and L{\"u}tkemeier, Sabine}, title = {Coupled models for the hydrological cycle : integrating atmosphere, biosphere and pedosphere}, publisher = {Springer-Verlag Berlin Heidelberg}, address = {Berlin, Heidelberg}, isbn = {3-540-22371-1}, doi = {10.1007/b138919}, pages = {345 S.}, year = {2005}, language = {en} } @article{KormannFranckeRenneretal.2015, author = {Kormann, C. and Francke, Till and Renner, M. and Bronstert, Axel}, title = {Attribution of high resolution streamflow trends in Western Austria}, series = {Hydrology and earth system sciences}, volume = {19}, journal = {Hydrology and earth system sciences}, publisher = {EGU}, address = {Katlenburg-Lindau}, issn = {1607-7938}, doi = {10.5194/hess-19-1225-2015}, pages = {1225 -- 1245}, year = {2015}, abstract = {The results of streamflow trend studies are often characterized by mostly insignificant trends and inexplicable spatial patterns. In our study region, Western Austria, this applies especially for trends of annually averaged runoff. However, analysing the altitudinal aspect, we found that there is a trend gradient from higher-altitude to lower-altitude stations, i.e. a pattern of mostly positive annual trends at higher stations and negative ones at lower stations. At midaltitudes, the trends are mostly insignificant. Here we hypothesize that the streamflow trends are caused by the following two main processes: on the one hand, melting glaciers produce excess runoff at higher-altitude watersheds. On the other hand, rising temperatures potentially alter hydrological conditions in terms of less snowfall, higher infiltration, enhanced evapotranspiration, etc., which in turn results in decreasing streamflow trends at lower-altitude watersheds. However, these patterns are masked at mid-altitudes because the resulting positive and negative trends balance each other. To support these hypotheses, we attempted to attribute the detected trends to specific causes. For this purpose, we analysed trends of filtered daily streamflow data, as the causes for these changes might be restricted to a smaller temporal scale than the annual one. This allowed for the explicit determination of the exact days of year (DOYs) when certain streamflow trends emerge, which were then linked with the corresponding DOYs of the trends and characteristic dates of other observed variables, e.g. the average DOY when temperature crosses the freezing point in spring. Based on these analyses, an empirical statistical model was derived that was able to simulate daily streamflow trends sufficiently well. Analyses of subdaily streamflow changes provided additional insights. Finally, the present study supports many modelling approaches in the literature which found out that the main drivers of alpine streamflow changes are increased glacial melt, earlier snowmelt and lower snow accumulation in wintertime.}, language = {en} } @article{DidovetsKrysanovaBuergeretal.2019, author = {Didovets, Iulii and Krysanova, Valentina and B{\"u}rger, Gerd and Snizhko, Sergiy and Balabukh, Vira and Bronstert, Axel}, title = {Climate change impact on regional floods in the Carpathian region}, series = {Journal of hydrology : Regional studies}, volume = {22}, journal = {Journal of hydrology : Regional studies}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2214-5818}, doi = {10.1016/j.ejrh.2019.01.002}, pages = {14}, year = {2019}, abstract = {Study region: Tisza and Prut catchments, originating on the slopes of the Carpathian mountains. Study focus: The study reported here investigates (i) climate change impacts on flood risk in the region, and (ii) uncertainty related to hydrological modelling, downscaling techniques and climate projections. The climate projections used in the study were derived from five GCMs, downscaled either dynamically with RCMs or with the statistical downscaling model XDS. The resulting climate change scenarios were applied to drive the eco-hydrological model SWIM, which was calibrated and validated for the catchments in advance using observed climate and hydrological data. The changes in the 30-year flood hazards and 98 and 95 percentiles of discharge were evaluated for the far future period (2071-2100) in comparison with the reference period (1981-2010). New hydrological insights for the region: The majority of model outputs under RCP 4.5 show a small to strong increase of the 30-year flood level in the Tisza ranging from 4.5\% to 62\%, and moderate increase in the Prut ranging from 11\% to 22\%. The impact results under RCP 8.5 are more uncertain with changes in both directions due to high uncertainties in GCM-RCM climate projections, downscaling methods and the low density of available climate stations.}, language = {en} } @article{KatzenmaierFritschBronstert2000, author = {Katzenmaier, Daniel and Fritsch, Uta and Bronstert, Axel}, title = {Influences of land-use and land-cover changes on storm-runoff generation}, year = {2000}, language = {en} } @article{FernandezPalominoHattermannKrysanovaetal.2022, author = {Fernandez-Palomino, Carlos Antonio and Hattermann, Fred and Krysanova, Valentina and Lobanova, Anastasia and Vega-Jacome, Fiorella and Lavado, Waldo and Santini, William and Aybar, Cesar and Bronstert, Axel}, title = {A novel high-resolution gridded precipitation dataset for peruvian and ecuadorian watersheds}, series = {Journal of hydrometeorology}, volume = {23}, journal = {Journal of hydrometeorology}, number = {3}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {1525-755X}, doi = {10.1175/JHM-D-20-0285.1}, pages = {309 -- 336}, year = {2022}, abstract = {A novel approach for estimating precipitation patterns is developed here and applied to generate a new hydrologically corrected daily precipitation dataset, called RAIN4PE (Rain for Peru and Ecuador), at 0.1 degrees spatial resolution for the period 1981-2015 covering Peru and Ecuador. It is based on the application of 1) the random forest method to merge multisource precipitation estimates (gauge, satellite, and reanalysis) with terrain elevation, and 2) observed and modeled streamflow data to first detect biases and second further adjust gridded precipitation by inversely applying the simulated results of the ecohydrological model SWAT (Soil and Water Assessment Tool). Hydrological results using RAIN4PE as input for the Peruvian and Ecuadorian catchments were compared against the ones when feeding other uncorrected (CHIRP and ERA5) and gauge-corrected (CHIRPS, MSWEP, and PISCO) precipitation datasets into the model. For that, SWAT was calibrated and validated at 72 river sections for each dataset using a range of performance metrics, including hydrograph goodness of fit and flow duration curve signatures. Results showed that gauge-corrected precipitation datasets outperformed uncorrected ones for streamflow simulation. However, CHIRPS, MSWEP, and PISCO showed limitations for streamflow simulation in several catchments draining into the Pacific Ocean and the Amazon River. RAIN4PE provided the best overall performance for streamflow simulation, including flow variability (low, high, and peak flows) and water budget closure. The overall good performance of RAIN4PE as input for hydrological modeling provides a valuable criterion of its applicability for robust countrywide hydrometeorological applications, including hydroclimatic extremes such as droughts and floods. Significance StatementWe developed a novel precipitation dataset RAIN4PE for Peru and Ecuador by merging multisource precipitation data (satellite, reanalysis, and ground-based precipitation) with terrain elevation using the random forest method. Furthermore, RAIN4PE was hydrologically corrected using streamflow data in watersheds with precipitation underestimation through reverse hydrology. The results of a comprehensive hydrological evaluation showed that RAIN4PE outperformed state-of-the-art precipitation datasets such as CHIRP, ERA5, CHIRPS, MSWEP, and PISCO in terms of daily and monthly streamflow simulations, including extremely low and high flows in almost all Peruvian and Ecuadorian catchments. This underlines the suitability of RAIN4PE for hydrometeorological applications in this region. Furthermore, our approach for the generation of RAIN4PE can be used in other data-scarce regions.}, language = {en} } @article{Bronstert, author = {Bronstert, Axel}, title = {Abflussbildung in der Landschaft}, series = {Hydrologie}, journal = {Hydrologie}, publisher = {Haupt Verlag}, address = {Bern}, isbn = {978-3-8252-4513-9}, pages = {143 -- 166}, language = {de} } @article{BronstertLange, author = {Bronstert, Axel and Lange, Jens}, title = {Hydrologie von Trockenregionen}, series = {Hydrologie}, journal = {Hydrologie}, publisher = {Haupt Verlag}, address = {Bern}, isbn = {978-3-8252-4513-9}, pages = {299 -- 312}, language = {de} } @article{VormoorRosslerBuergeretal.2017, author = {Vormoor, Klaus Josef and Rossler, Ole and B{\"u}rger, Gerd and Bronstert, Axel and Weingartner, Rolf}, title = {When timing matters-considering changing temporal structures in runoff response surfaces}, series = {Climatic change : an interdisciplinary, intern. journal devoted to the description, causes and implications of climatic change}, volume = {142}, journal = {Climatic change : an interdisciplinary, intern. journal devoted to the description, causes and implications of climatic change}, publisher = {Springer}, address = {Dordrecht}, issn = {0165-0009}, doi = {10.1007/s10584-017-1940-1}, pages = {213 -- 226}, year = {2017}, abstract = {Scenario-neutral response surfaces illustrate the sensitivity of a simulated natural system, represented by a specific impact variable, to systematic perturbations of climatic parameters. This type of approach has recently been developed as an alternative to top-down approaches for the assessment of climate change impacts. A major limitation of this approach is the underrepresentation of changes in the temporal structure of the climate input data (i.e., the seasonal and day-to-day variability) since this is not altered by the perturbation. This paper presents a framework that aims to examine this limitation by perturbing both observed and projected climate data time series for a future period, which both serve as input into a hydrological model (the HBV model). The resulting multiple response surfaces are compared at a common domain, the standardized runoff response surface (SRRS). We apply this approach in a case study catchment in Norway to (i) analyze possible changes in mean and extreme runoff and (ii) quantify the influence of changes in the temporal structure represented by 17 different climate input sets using linear mixed-effect models. Results suggest that climate change induced increases in mean and peak flow runoff and only small changes in low flow. They further suggest that the effect of the different temporal structures of the climate input data considerably affects low flows and floods (at least 21\% influence), while it is negligible for mean runoff.}, language = {en} } @article{vanSchaikBronstertdeJongetal.2014, author = {van Schaik, N. Loes M. B. and Bronstert, Axel and de Jong, S. M. and Jetten, V. G. and van Dam, J. C. and Ritsema, C. J. and Schnabel, Susanne}, title = {Process-based modelling of a headwater catchment in a semi-arid area: the influence of macropore flow}, series = {Hydrological processes}, volume = {28}, journal = {Hydrological processes}, number = {24}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0885-6087}, doi = {10.1002/hyp.10086}, pages = {5805 -- 5816}, year = {2014}, abstract = {Subsurface stormflow is thought to occur mainly in humid environments with steep terrains. However, in semi-arid areas, preferential flow through macropores can also result in a significant contribution of subsurface stormflow to catchment runoff for varying catchment conditions. Most hydrological models neglect this important subsurface preferential flow. Here, we use the process-oriented hydrological model Hillflow-3D, which includes a macropore flow approach, to simulate rainfall-runoff in the semi-arid Parapunos catchment in Spain, where macropore flow was observed in previous research. The model was extended for this study to account for sorptivity under very dry soil conditions. The results of the model simulations with and without macropore flow are compared. Both model versions give reasonable results for average rainfall situations, although the approach with the macropore concept provides slightly better results. The model results for scenarios of extreme rainfall events (>13.3mm30min(-1)) however show large differences between the versions with and without macropores. These model results compared with measured rainfall-runoff data show that the model with the macropore concept is better. Our conclusion is that preferential flow is important in controlling surface runoff in case of specific, high intensity rainfall events. Therefore, preferential flow processes must be included in hydrological models where we know that preferential flow occurs. Hydrological process models with a less detailed process description may fit observed average events reasonably well but can result in erroneous predictions for more extreme events. Copyright (c) 2013 John Wiley \& Sons, Ltd.}, language = {en} } @article{SalazarFrancesKommaetal.2012, author = {Salazar, S. and Frances, F. and Komma, J. and Blume, Theresa and Francke, Till and Bronstert, Axel and Bl{\"o}schl, G{\"u}nter}, title = {A comparative analysis of the effectiveness of flood management measures based on the concept of "retaining water in the landscape" in different European hydro-climatic regions}, series = {Natural hazards and earth system sciences}, volume = {12}, journal = {Natural hazards and earth system sciences}, number = {11}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-12-3287-2012}, pages = {3287 -- 3306}, year = {2012}, abstract = {In this paper, we analyse the effectiveness of flood management measures based on the concept known as "retaining water in the landscape". The investigated measures include afforestation, micro-ponds and small-reservoirs. A comparative and model-based methodological approach has been developed and applied for three meso-scale catchments located in different European hydro-climatological regions: Poyo (184 km(2)) in the Spanish Mediterranean, Upper Iller (954 km(2)) in the German Alps and Kamp (621 km(2)) in Northeast-Austria representing the Continental hydro-climate. This comparative analysis has found general similarities in spite of the particular differences among studied areas. In general terms, the flood reduction through the concept of "retaining water in the landscape" depends on the following factors: the storage capacity increase in the catchment resulting from such measures, the characteristics of the rainfall event, the antecedent soil moisture condition and the spatial distribution of such flood management measures in the catchment. In general, our study has shown that, this concept is effective for small and medium events, but almost negligible for the largest and less frequent floods: this holds true for all different hydro-climatic regions, and with different land-use, soils and morphological settings.}, language = {en} } @article{BuergerHeistermannBronstert2014, author = {B{\"u}rger, Gerd and Heistermann, Maik and Bronstert, Axel}, title = {Towards subdaily rainfall disaggregation via Clausius-Clapeyron}, series = {Journal of hydrometeorology}, volume = {15}, journal = {Journal of hydrometeorology}, number = {3}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {1525-755X}, doi = {10.1175/JHM-D-13-0161.1}, pages = {1303 -- 1311}, year = {2014}, abstract = {Two lines of research are combined in this study: first, the development of tools for the temporal disaggregation of precipitation, and second, some newer results on the exponential scaling of heavy short-term precipitation with temperature, roughly following the Clausius-Clapeyron (CC) relation. Having no extra temperature dependence, the traditional disaggregation schemes are shown to lack the crucial CC-type temperature dependence. The authors introduce a proof-of-concept adjustment of an existing disaggregation tool, the multiplicative cascade model of Olsson, and show that, in principal, it is possible to include temperature dependence in the disaggregation step, resulting in a fairly realistic temperature dependence of the CC type. They conclude by outlining the main calibration steps necessary to develop a full-fledged CC disaggregation scheme and discuss possible applications.}, language = {en} } @article{CostaBronstertdeAraujo2012, author = {Costa, A. C. and Bronstert, Axel and de Araujo, Jose Carlos}, title = {A channel transmission losses model for different dryland rivers}, series = {Hydrology and earth system sciences : HESS}, volume = {16}, journal = {Hydrology and earth system sciences : HESS}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-16-1111-2012}, pages = {1111 -- 1135}, year = {2012}, abstract = {Channel transmission losses in drylands take place normally in extensive alluvial channels or streambeds underlain by fractured rocks. They can play an important role in streamflow rates, groundwater recharge, freshwater supply and channel-associated ecosystems. We aim to develop a process-oriented, semi-distributed channel transmission losses model, using process formulations which are suitable for data-scarce dryland environments and applicable to both hydraulically disconnected losing streams and hydraulically connected losing(/gaining) streams. This approach should be able to cover a large variation in climate and hydro-geologic controls, which are typically found in dryland regions of the Earth. Our model was first evaluated for a losing/gaining, hydraulically connected 30 km reach of the Middle Jaguaribe River (MJR), Ceara, Brazil, which drains a catchment area of 20 000 km(2). Secondly, we applied it to a small losing, hydraulically disconnected 1.5 km channel reach in the Walnut Gulch Experimental Watershed (WGEW), Arizona, USA. The model was able to predict reliably the streamflow volume and peak for both case studies without using any parameter calibration procedure. We have shown that the evaluation of the hypotheses on the dominant hydrological processes was fundamental for reducing structural model uncertainties and improving the streamflow prediction. For instance, in the case of the large river reach (MJR), it was shown that both lateral stream-aquifer water fluxes and groundwater flow in the underlying alluvium parallel to the river course are necessary to predict streamflow volume and channel transmission losses, the former process being more relevant than the latter. Regarding model uncertainty, it was shown that the approaches, which were applied for the unsaturated zone processes (highly nonlinear with elaborate numerical solutions), are much more sensitive to parameter variability than those approaches which were used for the saturated zone (mathematically simple water budgeting in aquifer columns, including backwater effects). In case of the MJR-application, we have seen that structural uncertainties due to the limited knowledge of the subsurface saturated system interactions (i.e. groundwater coupling with channel water; possible groundwater flow parallel to the river) were more relevant than those related to the subsurface parameter variability. In case of the WEGW application we have seen that the non-linearity involved in the unsaturated flow processes in disconnected dryland river systems (controlled by the unsaturated zone) generally contain far more model uncertainties than do connected systems controlled by the saturated flow. Therefore, the degree of aridity of a dryland river may be an indicator of potential model uncertainty and subsequent attainable predictability of the system.}, language = {en} } @article{KormannFranckeRenneretal.2015, author = {Kormann, Christoph and Francke, Till and Renner, M. and Bronstert, Axel}, title = {Attribution of high resolution streamflow trends in Western Austria - an approach based on climate and discharge station data}, series = {Hydrology and earth system sciences : HESS}, volume = {19}, journal = {Hydrology and earth system sciences : HESS}, number = {3}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-19-1225-2015}, pages = {1225 -- 1245}, year = {2015}, abstract = {The results of streamflow trend studies are often characterized by mostly insignificant trends and inexplicable spatial patterns. In our study region, Western Austria, this applies especially for trends of annually averaged runoff. However, analysing the altitudinal aspect, we found that there is a trend gradient from higher-altitude to lower-altitude stations, i.e. a pattern of mostly positive annual trends at higher stations and negative ones at lower stations. At mid-altitudes, the trends are mostly insignificant. Here we hypothesize that the streamflow trends are caused by the following two main processes: on the one hand, melting glaciers produce excess runoff at higher-altitude watersheds. On the other hand, rising temperatures potentially alter hydrological conditions in terms of less snowfall, higher infiltration, enhanced evapotranspiration, etc., which in turn results in decreasing streamflow trends at lower-altitude watersheds. However, these patterns are masked at mid-altitudes because the resulting positive and negative trends balance each other. To support these hypotheses, we attempted to attribute the detected trends to specific causes. For this purpose, we analysed trends of filtered daily streamflow data, as the causes for these changes might be restricted to a smaller temporal scale than the annual one. This allowed for the explicit determination of the exact days of year (DOYs) when certain streamflow trends emerge, which were then linked with the corresponding DOYs of the trends and characteristic dates of other observed variables, e.g. the average DOY when temperature crosses the freezing point in spring. Based on these analyses, an empirical statistical model was derived that was able to simulate daily streamflow trends sufficiently well. Analyses of subdaily streamflow changes provided additional insights. Finally, the present study supports many modelling approaches in the literature which found out that the main drivers of alpine streamflow changes are increased glacial melt, earlier snowmelt and lower snow accumulation in wintertime.}, language = {en} } @article{MohrMangaWangetal.2015, author = {Mohr, Christian Heinrich and Manga, Michael and Wang, Chi-yuen and Kirchner, James W. and Bronstert, Axel}, title = {Shaking water out of soil}, series = {Geology}, volume = {43}, journal = {Geology}, number = {3}, publisher = {American Institute of Physics}, address = {Boulder}, issn = {0091-7613}, doi = {10.1130/G36261.1}, pages = {207 -- 210}, year = {2015}, abstract = {Moderate to large earthquakes can increase the amount of water flowing in streams. Previous interpretations and models assume that the extra water originates in the saturated zone. Here we show that earthquakes may also release water from the unsaturated zone when the seismic energy is sufficient to overcome the threshold of soil water retention. Soil water may then be released into aquifers, increasing streamflow. After the M8.8 Maule, Chile, earthquake, the discharge in some headwater catchments of the Chilean coastal range increased, and the amount of extra water in the discharge was similar to the total amount of water available for release from the unsaturated zone. Assuming rapid recharge of this water to the water table, a groundwater flow model that accounts for evapotranspiration and water released from soils can reproduce the increase in discharge as well as the enhanced diurnal discharge variations observed after the earthquake. Thus the unsaturated zone may play a previously unappreciated, and potentially significant, role in shallow hydrological responses to earthquakes.}, language = {en} } @article{MtilatilaBronstertShresthaetal.2020, author = {Mtilatila, Lucy Mphatso Ng'ombe and Bronstert, Axel and Shrestha, Pallav and Kadewere, Peter and Vormoor, Klaus Josef}, title = {Susceptibility of water resources and hydropower production to climate change in the tropics}, series = {Hydrology : open access journal}, volume = {7}, journal = {Hydrology : open access journal}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {2306-5338}, doi = {10.3390/hydrology7030054}, pages = {26}, year = {2020}, abstract = {The sensitivity of key hydrologic variables and hydropower generation to climate change in the Lake Malawi and Shire River basins is assessed. The study adapts the mesoscale Hydrological Model (mHM) which is applied separately in the Upper Lake Malawi and Shire River basins. A particular Lake Malawi model, which focuses on reservoir routing and lake water balance, has been developed and is interlinked between the two basins. Climate change projections from 20 Coordinated Regional Climate Downscaling Experiment (CORDEX) models for Africa based on two scenarios (RCP4.5 and RCP8.5) for the periods 2021-2050 and 2071-2100 are used. An annual temperature increase of 1 degrees C decreases mean lake level and outflow by 0.3 m and 17\%, respectively, signifying the importance of intensified evaporation for Lake Malawi's water budget. Meanwhile, a +5\% (-5\%) deviation in annual rainfall changes mean lake level by +0.7 m (-0.6 m). The combined effects of temperature increase and rainfall decrease result in significantly lower flows in the Shire River. The hydrological river regime may change from perennial to seasonal with the combination of annual temperature increase and precipitation decrease beyond 1.5 degrees C (3.5 degrees C) and -20\% (-15\%). The study further projects a reduction in annual hydropower production between 1\% (RCP8.5) and 2.5\% (RCP4.5) during 2021-2050 and between 5\% (RCP4.5) and 24\% (RCP8.5) during 2071-2100. The results show that it is of great importance that a further development of hydro energy on the Shire River should take into account the effects of climate change, e.g., longer low flow periods and/or higher discharge fluctuations, and thus uncertainty in the amount of electricity produced.}, language = {en} } @article{SeleemAyzelCostaTomazdeSouzaetal.2022, author = {Seleem, Omar and Ayzel, Georgy and Costa Tomaz de Souza, Arthur and Bronstert, Axel and Heistermann, Maik}, title = {Towards urban flood susceptibility mapping using data-driven models in Berlin, Germany}, series = {Geomatics, natural hazards and risk}, volume = {13}, journal = {Geomatics, natural hazards and risk}, number = {1}, publisher = {Taylor \& Francis}, address = {London}, issn = {1947-5705}, doi = {10.1080/19475705.2022.2097131}, pages = {1640 -- 1662}, year = {2022}, abstract = {Identifying urban pluvial flood-prone areas is necessary but the application of two-dimensional hydrodynamic models is limited to small areas. Data-driven models have been showing their ability to map flood susceptibility but their application in urban pluvial flooding is still rare. A flood inventory (4333 flooded locations) and 11 factors which potentially indicate an increased hazard for pluvial flooding were used to implement convolutional neural network (CNN), artificial neural network (ANN), random forest (RF) and support vector machine (SVM) to: (1) Map flood susceptibility in Berlin at 30, 10, 5, and 2 m spatial resolutions. (2) Evaluate the trained models' transferability in space. (3) Estimate the most useful factors for flood susceptibility mapping. The models' performance was validated using the Kappa, and the area under the receiver operating characteristic curve (AUC). The results indicated that all models perform very well (minimum AUC = 0.87 for the testing dataset). The RF models outperformed all other models at all spatial resolutions and the RF model at 2 m spatial resolution was superior for the present flood inventory and predictor variables. The majority of the models had a moderate performance for predictions outside the training area based on Kappa evaluation (minimum AUC = 0.8). Aspect and altitude were the most influencing factors on the image-based and point-based models respectively. Data-driven models can be a reliable tool for urban pluvial flood susceptibility mapping wherever a reliable flood inventory is available.}, language = {en} } @article{VormoorHeistermannBronstertetal.2018, author = {Vormoor, Klaus Josef and Heistermann, Maik and Bronstert, Axel and Lawrence, Deborah}, title = {Hydrological model parameter (in)stability}, series = {Hydrological sciences journal = Journal des sciences hydrologiques}, volume = {63}, journal = {Hydrological sciences journal = Journal des sciences hydrologiques}, number = {7}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0262-6667}, doi = {10.1080/02626667.2018.1466056}, pages = {991 -- 1007}, year = {2018}, abstract = {This paper investigates the transferability of calibrated HBV model parameters under stable and contrasting conditions in terms of flood seasonality and flood generating processes (FGP) in five Norwegian catchments with mixed snowmelt/rainfall regimes. We apply a series of generalized (differential) split-sample tests using a 6-year moving window over (i) the entire runoff observation periods, and (ii) two subsets of runoff observations distinguished by the seasonal occurrence of annual maximum floods during either spring or autumn. The results indicate a general model performance loss due to the transfer of calibrated parameters to independent validation periods of -5 to -17\%, on average. However, there is no indication that contrasting flood seasonality exacerbates performance losses, which contradicts the assumption that optimized parameter sets for snowmelt-dominated floods (during spring) perform particularly poorly on validation periods with rainfall-dominated floods (during autumn) and vice versa.}, language = {en} } @article{SeleemAyzelBronstertetal.2023, author = {Seleem, Omar and Ayzel, Georgy and Bronstert, Axel and Heistermann, Maik}, title = {Transferability of data-driven models to predict urban pluvial flood water depth in Berlin, Germany}, series = {Natural Hazards and Earth System Sciences}, volume = {23}, journal = {Natural Hazards and Earth System Sciences}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1684-9981}, doi = {10.5194/nhess-23-809-2023}, pages = {809 -- 822}, year = {2023}, abstract = {Data-driven models have been recently suggested to surrogate computationally expensive hydrodynamic models to map flood hazards. However, most studies focused on developing models for the same area or the same precipitation event. It is thus not obvious how transferable the models are in space. This study evaluates the performance of a convolutional neural network (CNN) based on the U-Net architecture and the random forest (RF) algorithm to predict flood water depth, the models' transferability in space and performance improvement using transfer learning techniques. We used three study areas in Berlin to train, validate and test the models. The results showed that (1) the RF models outperformed the CNN models for predictions within the training domain, presumable at the cost of overfitting; (2) the CNN models had significantly higher potential than the RF models to generalize beyond the training domain; and (3) the CNN models could better benefit from transfer learning technique to boost their performance outside training domains than RF models.}, language = {en} } @misc{PetrowHeistermannBronstert2017, author = {Petrow, Theresia and Heistermann, Maik and Bronstert, Axel}, title = {Analysis of Flash Floods in Germany}, series = {Hydrologie und Wasserbewirtschaftung}, volume = {61}, journal = {Hydrologie und Wasserbewirtschaftung}, publisher = {Bundesanst. f{\"u}r Gew{\"a}sserkunde}, address = {Koblenz}, issn = {1439-1783}, pages = {212 -- 212}, year = {2017}, language = {en} } @article{MiegelGraeffSelleetal.2016, author = {Miegel, Konrad and Graeff, Thomas and Selle, Benny and Salzmann, Thomas and Franck, Christian and Bronstert, Axel}, title = {Investigation of a renatured fen on the Baltic Sea coast of Mecklenburg - Part I: System description and basic hydrological characterisation}, series = {Hydrologie und Wasserbewirtschaftung}, volume = {60}, journal = {Hydrologie und Wasserbewirtschaftung}, publisher = {Bundesanst. f{\~A}¼r Gew{\~A}\isserkunde}, address = {Koblenz}, issn = {1439-1783}, doi = {10.5675/HyWa_2016.4_1}, pages = {242 -- 258}, year = {2016}, language = {de} } @article{BronstertKrolJaeger2000, author = {Bronstert, Axel and Krol, Marten S. and Jaeger, Annekathrin}, title = {WAVES : water availability, vulnerability of ecosystems and society in northeast brazil ; an overview of the interdisciplinary project and integrated modelling}, year = {2000}, language = {en} } @article{BronstertFritschKatzenmaieretal.2000, author = {Bronstert, Axel and Fritsch, Uta and Katzenmaier, Daniel and Bismuth, Christine}, title = {Quantification of the influence of the land-surface and river training on flood discharge of the Rhine Basin}, year = {2000}, language = {en} } @article{BronstertKundzewiczMenzel2000, author = {Bronstert, Axel and Kundzewicz, Zbigniew W. and Menzel, Lucas}, title = {Achievements and future needs towards improved flood protection in the Oder river basin : results of the EU- expert meeting on the Oder flood in Summer '97}, isbn = {0-7923-6451-1, 0-7923-6452-X}, year = {2000}, language = {en} } @article{BardossyBronstertBuiteveldetal.2000, author = {B{\´a}rdossy, Andras and Bronstert, Axel and Buiteveld, Hendrik and Disse, Markus and Fritsch, Uta and Katzenmaier, Daniel and Lammersen, Rita}, title = {Influence of the land surface and river training on flood conditions in the Rhine basin}, year = {2000}, language = {en} } @article{BronstertKrolJaegeretal.2000, author = {Bronstert, Axel and Krol, Marten S. and Jaeger, Annekathrin and G{\"u}ntner, Andreas and Hauschild, M. and D{\"o}ll, P.}, title = {Integrated modelling of water availability an management in the semi-arid Notheast of Brazil}, year = {2000}, language = {en} } @article{MenzelBronstertBuergeretal.2000, author = {Menzel, Lucas and Bronstert, Axel and B{\"u}rger, Gerd and Krysanova, Valentina}, title = {Environmental change scenarios and flood responses in the Elbe catchment (Germany)}, year = {2000}, language = {en} } @article{FritschKatzenmaierBronstert2000, author = {Fritsch, Uta and Katzenmaier, Daniel and Bronstert, Axel}, title = {Land-use and land-cover scenarios for flood risk analysis and river basin management}, year = {2000}, language = {en} } @article{Bronstert2000, author = {Bronstert, Axel}, title = {The possible impacts of environmental changes on flood formation : relevant processes and model requirements}, year = {2000}, language = {en} } @article{BronstertGuentner2000, author = {Bronstert, Axel and G{\"u}ntner, Andreas}, title = {A large-scale hydrological model for the semi-arid environment of north-eastern Brazil}, year = {2000}, language = {en} } @article{BronstertKatzenmaierFritsch2000, author = {Bronstert, Axel and Katzenmaier, Daniel and Fritsch, Uta}, title = {Hochwasserproblematik und der Zusammenhang mit Landnutzungs- und Klima{\"a}nderungen}, year = {2000}, language = {de} } @article{BronstertLahmer2000, author = {Bronstert, Axel and Lahmer, Werner}, title = {Bewirtschaftungsm{\"o}glichkeiten im Einzugsgebiet der Havel}, year = {2000}, language = {de} } @misc{KneisAbonBronstertetal.2016, author = {Kneis, David and Abon, Catherine Cristobal and Bronstert, Axel and Heistermann, Maik}, title = {Verification of short-term runoff forecasts for a small Philippine basin (Marikina)}, series = {Hydrological sciences journal = Journal des sciences hydrologiques}, volume = {62}, journal = {Hydrological sciences journal = Journal des sciences hydrologiques}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0262-6667}, doi = {10.1080/02626667.2016.1183773}, pages = {205 -- 216}, year = {2016}, abstract = {Storm runoff from the Marikina River Basin frequently causes flood events in the Philippine capital region Metro Manila. This paper presents and evaluates a system to predict short-term runoff from the upper part of that basin (380km(2)). It was designed as a possible component of an operational warning system yet to be installed. For the purpose of forecast verification, hindcasts of streamflow were generated for a period of 15 months with a time-continuous, conceptual hydrological model. The latter was fed with real-time observations of rainfall. Both ground observations and weather radar data were tested as rainfall forcings. The radar-based precipitation estimates clearly outperformed the raingauge-based estimates in the hydrological verification. Nevertheless, the quality of the deterministic short-term runoff forecasts was found to be limited. For the radar-based predictions, the reduction of variance for lead times of 1, 2 and 3hours was 0.61, 0.62 and 0.54, respectively, with reference to a no-forecast scenario, i.e. persistence. The probability of detection for major increases in streamflow was typically less than 0.5. Given the significance of flood events in the Marikina Basin, more effort needs to be put into the reduction of forecast errors and the quantification of remaining uncertainties.}, language = {en} } @article{RottlerFranckeBuergeretal.2020, author = {Rottler, Erwin and Francke, Till and B{\"u}rger, Gerd and Bronstert, Axel}, title = {Long-term changes in central European river discharge for 1869-2016}, series = {Hydrology and Earth System Sciences}, volume = {24}, journal = {Hydrology and Earth System Sciences}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-24-1721-2020}, pages = {1721 -- 1740}, year = {2020}, abstract = {Recent climatic changes have the potential to severely alter river runoff, particularly in snow-dominated river basins. Effects of changing snow covers superimpose with changes in precipitation and anthropogenic modifications of the watershed and river network. In the attempt to identify and disentangle long-term effects of different mechanisms, we employ a set of analytical tools to extract long-term changes in river runoff at high resolution. We combine quantile sampling with moving average trend statistics and empirical mode decomposition and apply these tools to discharge data recorded along rivers with nival, pluvial and mixed flow regimes as well as temperature and precipitation data covering the time frame 1869-2016. With a focus on central Europe, we analyse the long-term impact of snow cover and precipitation changes along with their interaction with reservoir constructions. Our results show that runoff seasonality of snow-dominated rivers decreases. Runoff increases in winter and spring, while discharge decreases in summer and at the beginning of autumn. We attribute this redistribution of annual flow mainly to reservoir constructions in the Alpine ridge. During the course of the last century, large fractions of the Alpine rivers were dammed to produce hydropower. In recent decades, runoff changes induced by reservoir constructions seem to overlap with changes in snow cover. We suggest that Alpine signals propagate downstream and affect runoff far outside the Alpine area in river segments with mixed flow regimes. Furthermore, our results hint at more (intense) rain-fall in recent decades. Detected increases in high discharge can be traced back to corresponding changes in precipitation.}, language = {en} } @article{RottlerVormoorFranckeetal.2021, author = {Rottler, Erwin and Vormoor, Klaus Josef and Francke, Till and Warscher, Michael and Strasser, Ulrich and Bronstert, Axel}, title = {Elevation-dependent compensation effects in snowmelt in the Rhine River Basin upstream gauge Basel}, series = {Hydrology research : an international journal / Nordic Association of Hydrology ; British Hydrological Society}, volume = {52}, journal = {Hydrology research : an international journal / Nordic Association of Hydrology ; British Hydrological Society}, number = {2}, publisher = {IWA Publ.}, address = {London}, issn = {2224-7955}, doi = {10.2166/nh.2021.092}, pages = {536 -- 557}, year = {2021}, abstract = {In snow-dominated river basins, floods often occur during early summer, when snowmelt-induced runoff superimposes with rainfall-induced runoff. An earlier onset of seasonal snowmelt as a consequence of a warming climate is often expected to shift snowmelt contribution to river runoff and potential flooding to an earlier date. Against this background, we assess the impact of rising temperatures on seasonal snowpacks and quantify changes in timing, magnitude and elevation of snowmelt. We analyse in situ snow measurements, conduct snow simulations and examine changes in river runoff at key gauging stations. With regard to snowmelt, we detect a threefold effect of rising temperatures: snowmelt becomes weaker, occurs earlier and forms at higher elevations. Due to the wide range of elevations in the catchment, snowmelt does not occur simultaneously at all elevations. Results indicate that elevation bands melt together in blocks. We hypothesise that in a warmer world with similar sequences of weather conditions, snowmelt is moved upward to higher elevation. The movement upward the elevation range makes snowmelt in individual elevation bands occur earlier, although the timing of the snowmelt-induced runoff stays the same. Meltwater from higher elevations, at least partly, replaces meltwater from elevations below.}, language = {en} } @article{MtilatilaBronstertVormoor2022, author = {Mtilatila, Lucy Mphatso Ng'ombe and Bronstert, Axel and Vormoor, Klaus Josef}, title = {Temporal evaluation and projections of meteorological droughts in the Greater Lake Malawi Basin, Southeast Africa}, series = {Frontiers in water}, volume = {4}, journal = {Frontiers in water}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2624-9375}, doi = {10.3389/frwa.2022.1041452}, pages = {16}, year = {2022}, abstract = {The study examined the potential future changes of drought characteristics in the Greater Lake Malawi Basin in Southeast Africa. This region strongly depends on water resources to generate electricity and food. Future projections (considering both moderate and high emission scenarios) of temperature and precipitation from an ensemble of 16 bias-corrected climate model combinations were blended with a scenario-neutral response surface approach to analyses changes in: (i) the meteorological conditions, (ii) the meteorological water balance, and (iii) selected drought characteristics such as drought intensity, drought months, and drought events, which were derived from the Standardized Precipitation and Evapotranspiration Index. Changes were analyzed for a near-term (2021-2050) and far-term period (2071-2100) with reference to 1976-2005. The effect of bias-correction (i.e., empirical quantile mapping) on the ability of the climate model ensemble to reproduce observed drought characteristics as compared to raw climate projections was also investigated. Results suggest that the bias-correction improves the climate models in terms of reproducing temperature and precipitation statistics but not drought characteristics. Still, despite the differences in the internal structures and uncertainties that exist among the climate models, they all agree on an increase of meteorological droughts in the future in terms of higher drought intensity and longer events. Drought intensity is projected to increase between +25 and +50\% during 2021-2050 and between +131 and +388\% during 2071-2100. This translates into +3 to +5, and +7 to +8 more drought months per year during both periods, respectively. With longer lasting drought events, the number of drought events decreases. Projected droughts based on the high emission scenario are 1.7 times more severe than droughts based on the moderate scenario. That means that droughts in this region will likely become more severe in the coming decades. Despite the inherent high uncertainties of climate projections, the results provide a basis in planning and (water-)managing activities for climate change adaptation measures in Malawi. This is of particular relevance for water management issues referring hydro power generation and food production, both for rain-fed and irrigated agriculture.}, language = {en} } @article{BuergerPfisterBronstert2019, author = {B{\"u}rger, Gerd and Pfister, A. and Bronstert, Axel}, title = {Temperature-Driven Rise in Extreme Sub-Hourly Rainfall}, series = {Journal of climate}, volume = {32}, journal = {Journal of climate}, number = {22}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {0894-8755}, doi = {10.1175/JCLI-D-19-0136.1}, pages = {7597 -- 7609}, year = {2019}, abstract = {Estimates of present and future extreme sub-hourly rainfall are derived from a daily spatial followed by a sub-daily temporal downscaling, the latter of which incorporates a novel, and crucial, temperature sensitivity. Specifically, daily global climate fields are spatially downscaled to local temperature T and precipitation P, which are then disaggregated to a temporal resolution of 10 min using a multiplicative random cascade model. The scheme is calibrated and validated with a group of 21 station records of 10-min resolution in Germany. The cascade model is used in the classical (denoted as MC) and in the new T-sensitive (MC+) version, which respects local Clausius-Clapeyron (CC) effects such as CC scaling. Extreme P is positively biased in both MC versions. Observed T sensitivity is absent in MC but well reproduced by MC+. Long-term positive trends in extreme sub-hourly P are generally more pronounced and more significant in MC+ than in MC. In units of 10-min rainfall, observed centennial trends in annual exceedance counts (EC) of P > 5 mm are +29\% and in 3-yr return levels (RL) +27\%. For the RCP4.5-simulated future, higher extremes are projected in both versions MC and MC+: per century, EC increases by 30\% for MC and by 83\% for MC+; the RL rises by 14\% for MC and by 33\% for MC+. Because the projected daily P trends are negligible, the sub-daily signal is mainly driven by local temperature.}, language = {en} } @misc{PilzDelgadoVossetal.2019, author = {Pilz, Tobias and Delgado, Jos{\´e} Miguel Martins and Voss, Sebastian and Vormoor, Klaus Josef and Francke, Till and Cunha Costa, Alexandre and Martins, Eduardo and Bronstert, Axel}, title = {Seasonal drought prediction for semiarid northeast Brazil}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {702}, issn = {1866-8372}, doi = {10.25932/publishup-42795}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427950}, pages = {21}, year = {2019}, abstract = {The semiarid northeast of Brazil is one of the most densely populated dryland regions in the world and recurrently affected by severe droughts. Thus, reliable seasonal forecasts of streamflow and reservoir storage are of high value for water managers. Such forecasts can be generated by applying either hydrological models representing underlying processes or statistical relationships exploiting correlations among meteorological and hydrological variables. This work evaluates and compares the performances of seasonal reservoir storage forecasts derived by a process-based hydrological model and a statistical approach. Driven by observations, both models achieve similar simulation accuracies. In a hindcast experiment, however, the accuracy of estimating regional reservoir storages was considerably lower using the process-based hydrological model, whereas the resolution and reliability of drought event predictions were similar by both approaches. Further investigations regarding the deficiencies of the process-based model revealed a significant influence of antecedent wetness conditions and a higher sensitivity of model prediction performance to rainfall forecast quality. Within the scope of this study, the statistical model proved to be the more straightforward approach for predictions of reservoir level and drought events at regionally and monthly aggregated scales. However, for forecasts at finer scales of space and time or for the investigation of underlying processes, the costly initialisation and application of a process-based model can be worthwhile. Furthermore, the application of innovative data products, such as remote sensing data, and operational model correction methods, like data assimilation, may allow for an enhanced exploitation of the advanced capabilities of process-based hydrological models.}, language = {en} } @article{KrauseBronstert2004, author = {Krause, Stefan and Bronstert, Axel}, title = {Wasserhaushaltssimulationen unter Einbeziehung von Grundwasser - Oberfl{\"a}chenwasser - Kopplung zur Optimierung szenarienbasierter Handlungsoptionen f{\"u}r ein nachhaltiges Flussgebietsmanagement an der Unteren Havel}, isbn = {3-89958-072-9}, year = {2004}, language = {de} } @article{KneisKnoescheBronstert2004, author = {Kneis, David and Kn{\"o}sche, R{\"u}diger and Bronstert, Axel}, title = {Ist ein Netto-N{\"a}hrstoffexport aus Flussgew{\"a}ssersedimenten eine realistische Option zur Trophiesenkung?}, isbn = {3-937758-18-6}, year = {2004}, language = {de} } @article{KrauseBronstert2004, author = {Krause, Stefan and Bronstert, Axel}, title = {Approximation of Groundwater - Surface Water - Interactions in a Mesoscale Lowland River Catchment}, year = {2004}, language = {en} } @article{Bronstert2004, author = {Bronstert, Axel}, title = {Probleme, Grenzen und Herausforderungen der hydrologischen Modellierung: Wasserhaushalt und Abfluss}, year = {2004}, language = {de} } @book{KundzewiczBudhakooncharoenBronstertetal.2001, author = {Kundzewicz, Zbigniew W. and Budhakooncharoen, Saisunee and Bronstert, Axel and Hoff, Holger and Lettenmaier, Dennis P. and Menzel, Lucas and Schulze, Roland}, title = {Floods and droughts : coping with variability and climate change ; thematic backround paper [for the International Conference on Freshwater 2001, Bonn, 3-7 December 2001]}, publisher = {Secretariat of the International Conference on Freshwater}, address = {Bonn}, pages = {29 S.}, year = {2001}, language = {en} } @article{GuentnerBronstert2001, author = {G{\"u}ntner, Andreas and Bronstert, Axel}, title = {WAVES - Water availability, vulnerability of ecosystems and society in the northeast of Brazil : sub-project large-scale hydrological modelling}, year = {2001}, language = {en} } @article{KatzenmaierFritschBronstert2001, author = {Katzenmaier, Daniel and Fritsch, Uta and Bronstert, Axel}, title = {Quantifizierung des Einflusses von Landnutzung und dezentraler Versickerung auf die Hochwasserentstehung}, isbn = {3-503-06021-9}, year = {2001}, language = {de} } @article{KrolJaegerBronstertetal.2001, author = {Krol, Marten S. and Jaeger, Annekathrin and Bronstert, Axel and Krywkow, J.}, title = {The Semi-arid Integrated Model (SIM), a regional integrated model assessing water availability, vulnerability of ecosystems and society in NE-Brazil}, year = {2001}, language = {en} } @article{GuentnerBronstert2001, author = {G{\"u}ntner, Andreas and Bronstert, Axel}, title = {Modelling the effects of climate change on water availability in the semi-arid of North-East Brazil}, year = {2001}, language = {en} } @article{NiehoffBronstert2001, author = {Niehoff, Daniel and Bronstert, Axel}, title = {Influences of land-use and land-surface conditions on flood generation : a simulation study}, year = {2001}, language = {en} } @article{KundzewiczBudhakooncharoenBronstertetal.2001, author = {Kundzewicz, Zbigniew W. and Budhakooncharoen, Saisunee and Bronstert, Axel and Hoff, Holger and Lettenmaier, Dennis P. and Menzel, Lucas and Schulze, Roland}, title = {Coping with variability and climate change : floods and droughts}, year = {2001}, language = {en} } @article{BronstertFritschLeonhardtetal.2001, author = {Bronstert, Axel and Fritsch, Uta and Leonhardt, H. and Niehoff, Daniel}, title = {Quantifizierung des Einflusses von Landnutzungs- und Klima{\"a}nderungen auf die Hochwasserentstehung am Beispiel ausgew{\"a}hlter Flussgebiete}, year = {2001}, language = {de} } @article{Bronstert2001, author = {Bronstert, Axel}, title = {The role of infiltration conditions for storm runoff generation at the hillslope and small catchment scale}, year = {2001}, language = {en} } @article{GraeffZeheSchlaegeretal.2010, author = {Gr{\"a}ff, Thomas and Zehe, Erwin and Schl{\"a}ger, Stefan and Morgner, Markus and Bauer, Andreas and Becker, Rolf and Creutzfeldt, Benjamin and Bronstert, Axel}, title = {A quality assessment of spatial TDR soil moisture measurements in homogenous and heterogeneous media with laboratory experiments}, issn = {1812-2108}, doi = {10.5194/hessd-7-269-2010}, year = {2010}, abstract = {Investigation of transient soil moisture profiles yields valuable information of near- surface processes. A recently developed reconstruction algorithm based on the telegraph equation allows the inverse estimation of soil moisture profiles along coated, three rod TDR probes. Laboratory experiments were carried out to prove the results of the inversion and to understand the influence of probe rod deformation and solid objects close to the probe in heterogonous media. Differences in rod geometry can lead to serious misinterpretations in the soil moisture profile but have small influence on the average soil moisture along the probe. Solids in the integration volume have almost no effect on average soil moisture but result in locally slightly decreased moisture values. Inverted profiles obtained in a loamy soil with a clay content of about 16\% were in good agreement with independent measurements.}, language = {en} } @article{SeleemHeistermannBronstert2021, author = {Seleem, Omar and Heistermann, Maik and Bronstert, Axel}, title = {Efficient Hazard Assessment For Pluvial Floods In Urban Environments}, series = {Water}, volume = {13}, journal = {Water}, number = {18}, publisher = {MDPI}, address = {Basel}, issn = {2073-4441}, doi = {10.3390/w13182476}, pages = {17}, year = {2021}, abstract = {The presence of impermeable surfaces in urban areas hinders natural drainage and directs the surface runoff to storm drainage systems with finite capacity, which makes these areas prone to pluvial flooding. The occurrence of pluvial flooding depends on the existence of minimal areas for surface runoff generation and concentration. Detailed hydrologic and hydrodynamic simulations are computationally expensive and require intensive resources. This study compared and evaluated the performance of two simplified methods to identify urban pluvial flood-prone areas, namely the fill-spill-merge (FSM) method and the topographic wetness index (TWI) method and used the TELEMAC-2D hydrodynamic numerical model for benchmarking and validation. The FSM method uses common GIS operations to identify flood-prone depressions from a high-resolution digital elevation model (DEM). The TWI method employs the maximum likelihood method (MLE) to probabilistically calibrate a TWI threshold (τ) based on the inundation maps from a 2D hydrodynamic model for a given spatial window (W) within the urban area. We found that the FSM method clearly outperforms the TWI method both conceptually and effectively in terms of model performance.}, language = {en} } @article{HeistermannCrisologoAbonetal.2013, author = {Heistermann, Maik and Crisologo, Irene and Abon, Catherine Cristobal and Racoma, B. A. and Jacobi, S. and Servando, N. T. and David, C. P. C. and Bronstert, Axel}, title = {Using the new Philippine radar network to reconstruct the Habagat of August 2012 monsoon event around Metropolitan Manila}, series = {Natural hazards and earth system sciences}, volume = {13}, journal = {Natural hazards and earth system sciences}, number = {3}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-13-653-2013}, pages = {653 -- 657}, year = {2013}, abstract = {From 6 to 9 August 2012, intense rainfall hit the northern Philippines, causing massive floods in Metropolitan Manila and nearby regions. Local rain gauges recorded almost 1000mm within this period. However, the recently installed Philippine network of weather radars suggests that Metropolitan Manila might have escaped a potentially bigger flood just by a whisker, since the centre of mass of accumulated rainfall was located over Manila Bay. A shift of this centre by no more than 20 km could have resulted in a flood disaster far worse than what occurred during Typhoon Ketsana in September 2009.}, language = {en} } @incollection{BronstertCrisologoHeistermannetal.2020, author = {Bronstert, Axel and Crisologo, Irene and Heistermann, Maik and {\"O}zt{\"u}rk, Ugur and Vogel, Kristin and Wendi, Dadiyorto}, title = {Flash-floods: more often, more severe, more damaging?}, series = {Climate change, hazards and adaptation options: handling the impacts of a changing climate}, booktitle = {Climate change, hazards and adaptation options: handling the impacts of a changing climate}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-37425-9}, issn = {1610-2010}, doi = {10.1007/978-3-030-37425-9_12}, pages = {225 -- 244}, year = {2020}, abstract = {In recent years, urban and rural flash floods in Europe and abroad have gained considerable attention because of their sudden occurrence, severe material damages and even danger to life of inhabitants. This contribution addresses questions about possibly changing environmental conditions which might have altered the occurrence frequencies of such events and their consequences. We analyze the following major fields of environmental changes. Altered high intensity rain storm conditions, as a consequence of regionalwarming; Possibly altered runoff generation conditions in response to high intensity rainfall events; Possibly altered runoff concentration conditions in response to the usage and management of the landscape, such as agricultural, forest practices or rural roads; Effects of engineering measures in the catchment, such as retention basins, check dams, culverts, or river and geomorphological engineering measures. We take the flash-flood in Braunsbach, SW-Germany, as an example, where a particularly concise flash flood event occurred at the end of May 2016. This extreme cascading natural event led to immense damage in this particular village. The event is retrospectively analyzed with regard to meteorology, hydrology, geomorphology and damage to obtain a quantitative assessment of the processes and their development. The results show that it was a very rare rainfall event with extreme intensities, which in combination with catchment properties and altered environmental conditions led to extreme runoff, extreme debris flow and immense damages. Due to the complex and interacting processes, no single flood cause can be identified, since only the interplay of those led to such an event. We have shown that environmental changes are important, but-at least for this case study-even natural weather and hydrologic conditions would still have resulted in an extreme flash flood event.}, language = {en} } @article{BronstertKoehler2000, author = {Bronstert, Axel and K{\"o}hler, Birgit}, title = {Simulation der Einfl{\"u}sse anthropogener Klima{\"a}nderungen auf die Hochwasserentstehung : eine Fallstudie in einem kleinen l{\"a}ndlichen Einzugsgebiet im Ostharz}, year = {2000}, language = {de} } @article{BronstertCreutzfeldtGraeffetal.2012, author = {Bronstert, Axel and Creutzfeldt, Benjamin and Gr{\"a}ff, Thomas and Hajnsek, Irena and Heistermann, Maik and Itzerott, Sibylle and Jagdhuber, Thomas and Kneis, David and Lueck, Erika and Reusser, Dominik and Zehe, Erwin}, title = {Potentials and constraints of different types of soil moisture observations for flood simulations in headwater catchments}, series = {Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards}, volume = {60}, journal = {Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards}, number = {3}, publisher = {Springer}, address = {New York}, issn = {0921-030X}, doi = {10.1007/s11069-011-9874-9}, pages = {879 -- 914}, year = {2012}, abstract = {Flood generation in mountainous headwater catchments is governed by rainfall intensities, by the spatial distribution of rainfall and by the state of the catchment prior to the rainfall, e. g. by the spatial pattern of the soil moisture, groundwater conditions and possibly snow. The work presented here explores the limits and potentials of measuring soil moisture with different methods and in different scales and their potential use for flood simulation. These measurements were obtained in 2007 and 2008 within a comprehensive multi-scale experiment in the Weisseritz headwater catchment in the Ore-Mountains, Germany. The following technologies have been applied jointly thermogravimetric method, frequency domain reflectometry (FDR) sensors, spatial time domain reflectometry (STDR) cluster, ground-penetrating radar (GPR), airborne polarimetric synthetic aperture radar (polarimetric SAR) and advanced synthetic aperture radar (ASAR) based on the satellite Envisat. We present exemplary soil measurement results, with spatial scales ranging from point scale, via hillslope and field scale, to the catchment scale. Only the spatial TDR cluster was able to record continuous data. The other methods are limited to the date of over-flights (airplane and satellite) or measurement campaigns on the ground. For possible use in flood simulation, the observation of soil moisture at multiple scales has to be combined with suitable hydrological modelling, using the hydrological model WaSiM-ETH. Therefore, several simulation experiments have been conducted in order to test both the usability of the recorded soil moisture data and the suitability of a distributed hydrological model to make use of this information. The measurement results show that airborne-based and satellite-based systems in particular provide information on the near-surface spatial distribution. However, there are still a variety of limitations, such as the need for parallel ground measurements (Envisat ASAR), uncertainties in polarimetric decomposition techniques (polarimetric SAR), very limited information from remote sensing methods about vegetated surfaces and the non-availability of continuous measurements. The model experiments showed the importance of soil moisture as an initial condition for physically based flood modelling. However, the observed moisture data reflect the surface or near-surface soil moisture only. Hence, only saturated overland flow might be related to these data. Other flood generation processes influenced by catchment wetness in the subsurface such as subsurface storm flow or quick groundwater drainage cannot be assessed by these data. One has to acknowledge that, in spite of innovative measuring techniques on all spatial scales, soil moisture data for entire vegetated catchments are still today not operationally available. Therefore, observations of soil moisture should primarily be used to improve the quality of continuous, distributed hydrological catchment models that simulate the spatial distribution of moisture internally. Thus, when and where soil moisture data are available, they should be compared with their simulated equivalents in order to improve the parameter estimates and possibly the structure of the hydrological model.}, language = {en} } @article{ConradtWechsungBronstert2013, author = {Conradt, Tobias and Wechsung, F. and Bronstert, Axel}, title = {Three perceptions of the evapotranspiration landscape comparing spatial patterns from a distributed hydrological model, remotely sensed surface temperatures, and sub-basin water balances}, series = {Hydrology and earth system sciences : HESS}, volume = {17}, journal = {Hydrology and earth system sciences : HESS}, number = {7}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-17-2947-2013}, pages = {2947 -- 2966}, year = {2013}, abstract = {A problem encountered by many distributed hydrological modelling studies is high simulation errors at interior gauges when the model is only globally calibrated at the outlet. We simulated river runoff in the Elbe River basin in central Europe (148 268 km(2)) with the semi-distributed eco-hydrological model SWIM (Soil and Water Integrated Model). While global parameter optimisation led to Nash-Sutcliffe efficiencies of 0.9 at the main outlet gauge, comparisons with measured runoff series at interior points revealed large deviations. Therefore, we compared three different strategies for deriving sub-basin evapotranspiration: (1) modelled by SWIM without any spatial calibration, (2) derived from remotely sensed surface temperatures, and (3) calculated from long-term precipitation and discharge data. The results show certain consistencies between the modelled and the remote sensing based evapotranspiration rates, but there seems to be no correlation between remote sensing and water balance based estimations. Subsequent analyses for single sub-basins identify amongst others input weather data and systematic error amplification in inter-gauge discharge calculations as sources of uncertainty. The results encourage careful utilisation of different data sources for enhancements in distributed hydrological modelling.}, language = {en} } @article{FranckeFoersterBrosinskyetal.2018, author = {Francke, Till and F{\"o}rster, Saskia and Brosinsky, Arlena and Sommerer, Erik and Lopez-Tarazonl, Jose Andres and G{\"u}ntner, Andreas and Batalla, Ramon J. and Bronstert, Axel}, title = {Water and sediment fluxes in Mediterranean mountainous regions}, series = {Earth System Science Data}, volume = {10}, journal = {Earth System Science Data}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1866-3508}, doi = {10.5194/essd-10-1063-2018}, pages = {1063 -- 1075}, year = {2018}, abstract = {A comprehensive hydro-sedimentological dataset for the Isabena catchment, northeastern (NE) Spain, for the period 2010-2018 is presented to analyse water and sediment fluxes in a Mediterranean mesoscale catchment. The dataset includes rainfall data from 12 rain gauges distributed within the study area complemented by meteorological data of 12 official meteo-stations. It comprises discharge data derived from water stage measurements as well as suspended sediment concentrations (SSCs) at six gauging stations of the River Isabena and its sub-catchments. Soil spectroscopic data from 351 suspended sediment samples and 152 soil samples were collected to characterize sediment source regions and sediment properties via fingerprinting analyses. The Isabena catchment (445 km(2)) is located in the southern central Pyrenees ranging from 450 m to 2720 m a.s.l.; together with a pronounced topography, this leads to distinct temperature and precipitation gradients. The River Isabena shows marked discharge variations and high sediment yields causing severe siltation problems in the downstream Barasona Reservoir. The main sediment source is badland areas located on Eocene marls that are well connected to the river network. The dataset features a comprehensive set of variables in a high spatial and temporal resolution suitable for the advanced process understanding of water and sediment fluxes, their origin and connectivity and sediment budgeting and for the evaluation and further development of hydro-sedimentological models in Mediterranean mesoscale mountainous catchments.}, language = {en} } @article{BronstertBuergerPfister2021, author = {Bronstert, Axel and B{\"u}rger, Gerhard and Pfister, Angela}, title = {Vorhersage und Projektion von Sturzfluten - Vorwort}, series = {Hydrologie und Wasserbewirtschaftung : HyWa = Hydrology and water resources management, Germany / Hrsg.: Fachverwaltungen des Bundes und der L{\"a}nder}, volume = {65}, journal = {Hydrologie und Wasserbewirtschaftung : HyWa = Hydrology and water resources management, Germany / Hrsg.: Fachverwaltungen des Bundes und der L{\"a}nder}, number = {6}, publisher = {Bundesanst. f{\"u}r Gew{\"a}sserkunde, BfG}, address = {Koblenz}, issn = {1439-1783}, pages = {260 -- 261}, year = {2021}, language = {de} } @article{MohrMontgomeryHuberetal.2012, author = {Mohr, Christian Heinrich and Montgomery, David R. and Huber, Anton and Bronstert, Axel and Iroume, Andres}, title = {Streamflow response in small upland catchments in the Chilean coastal range to the M-W 8.8 Maule earthquake on 27 February 2010}, series = {Journal of geophysical research : Earth surface}, volume = {117}, journal = {Journal of geophysical research : Earth surface}, number = {23}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0148-0227}, doi = {10.1029/2011JF002138}, pages = {16}, year = {2012}, abstract = {Hydrological response to earthquakes has long been observed, yet the mechanisms responsible still remain unclear and likely vary in space and time. This study explores the base flow response in small upland catchments of the Coastal Range of south-central Chile after the M-W 8.8 Maule earthquake of 27 February 2010. An initial decline in streamflow followed by an increase of up to 400\% of the discharge measured immediately before the earthquake occurred, and diurnal streamflow oscillations intensified after the earthquake. Neither response time, nor time to maximum streamflow discharge showed any relationship with catchment topography or size, suggesting non-uniform release of water across the catchments. The fast response, unaffected stream water temperatures and a simple diffusion model point to the sandy saprolite as the source of the excess water. Base flow recession analysis reveals no evidence for substantial enhancement of lateral hydraulic conductivity in the saprolite after the earthquake. Seismic energy density reached similar to 170 J/m(3) for the main shock and similar to 0.9 J/m(3) for the aftershock, exceeding the threshold for liquefaction by undrained consolidation only during the main shock. Although increased hydraulic gradient due to ground acceleration-triggered, undrained consolidation is consistent with empirical magnitude-distance relationships for liquefaction, the lack of independent evidence for liquefaction means that enhanced vertical permeability (probably in combination with co-seismic near-surface dilatancy) cannot be excluded as a potential mechanism. Undrained consolidation may have released additional water from the saturated saprolite into the overlying soil, temporarily reducing water transfer to the creeks but enlarging the cross-section of the saturated zone, which in turn enhanced streamflow after establishment of a new hydraulic equilibrium. The enlarged saturated zone facilitated water uptake by roots and intensified evapotranspiration.}, language = {en} } @article{MohrCoppusIroumeetal.2013, author = {Mohr, Christian Heinrich and Coppus, Ruben and Iroume, Andres and Huber, Anton and Bronstert, Axel}, title = {Runoff generation and soil erosion processes after clear cutting}, series = {Journal of geophysical research : Earth surface}, volume = {118}, journal = {Journal of geophysical research : Earth surface}, number = {2}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9003}, doi = {10.1002/jgrf.20047}, pages = {814 -- 831}, year = {2013}, abstract = {Timber harvesting by clear cutting is known to impose environmental impacts, including severe disturbance of the soil hydraulic properties which intensify the frequency and magnitude of surface runoff and soil erosion. However, it remains unanswered if harvest areas act as sources or sinks for runoff and soil erosion and whether such behavior operates in a steady state or evolves through time. For this purpose, 92 small-scale rainfall simulations of different intensities were carried out under pine plantation conditions and on two clear-cut harvest areas of different age. Nonparametrical Random Forest statistical models were set up to quantify the impact of environmental variables on the hydrological and erosion response. Regardless of the applied rainfall intensity, runoff always initiated first and yielded most under plantation cover. Counter to expectations, infiltration rates increased after logging activities. Once a threshold rainfall intensity of 20mm/h was exceeded, the younger harvest area started to act as a source for both runoff and erosion after connectivity was established, whereas it remained a sink under lower applied rainfall intensities. The results suggest that the impact of microtopography on surface runoff connectivity and water-repellent properties of the topsoil act as first-order controls for the hydrological and erosion processes in such environments. Fast rainfall-runoff response, sediment-discharge-hystereses, and enhanced postlogging groundwater recharge at catchment scale support our interpretation. At the end, we show the need to account for nonstationary hydrological and erosional behavior of harvest areas, a fact previously unappreciated in predictive models.}, language = {en} } @article{PilzFranckeBronstert2017, author = {Pilz, Tobias and Francke, Till and Bronstert, Axel}, title = {lumpR 2.0.0: an R package facilitating landscape discretisation for hillslope-based hydrological models}, series = {Geoscientific model development : an interactive open access journal of the European Geosciences Union}, volume = {10}, journal = {Geoscientific model development : an interactive open access journal of the European Geosciences Union}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1991-959X}, doi = {10.5194/gmd-10-3001-2017}, pages = {3001 -- 3023}, year = {2017}, abstract = {The characteristics of a landscape pose essential factors for hydrological processes. Therefore, an adequate representation of the landscape of a catchment in hydrological models is vital. However, many of such models exist differing, amongst others, in spatial concept and discretisation. The latter constitutes an essential pre-processing step, for which many different algorithms along with numerous software implementations exist. In that context, existing solutions are often model specific, commercial, or depend on commercial back-end software, and allow only a limited or no workflow automation at all. Consequently, a new package for the scientific software and scripting environment R, called lumpR, was developed. lumpR employs an algorithm for hillslope-based landscape discretisation directed to large-scale application via a hierarchical multi-scale approach. The package addresses existing limitations as it is free and open source, easily extendible to other hydrological models, and the workflow can be fully automated. Moreover, it is user-friendly as the direct coupling to a GIS allows for immediate visual inspection and manual adjustment. Sufficient control is furthermore retained via parameter specification and the option to include expert knowledge. Conversely, completely automatic operation also allows for extensive analysis of aspects related to landscape discretisation. In a case study, the application of the package is presented. A sensitivity analysis of the most important discretisation parameters demonstrates its efficient workflow automation. Considering multiple streamflow metrics, the employed model proved reasonably robust to the discretisation parameters. However, parameters determining the sizes of subbasins and hillslopes proved to be more important than the others, including the number of representative hillslopes, the number of attributes employed for the lumping algorithm, and the number of sub-discretisations of the representative hillslopes.}, language = {en} } @article{KneisBuergerBronstert2012, author = {Kneis, David and Buerger, Gerd and Bronstert, Axel}, title = {Evaluation of medium-range runoff forecasts for a 50 km(2) watershed}, series = {Journal of hydrology}, volume = {414}, journal = {Journal of hydrology}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2011.11.005}, pages = {341 -- 353}, year = {2012}, abstract = {We generated medium-range forecasts of runoff for a 50 km(2) headwater catchment upstream of a reservoir using numerical weather predictions (NWPs) of the past as input to an operational hydrological model. NWP data originating from different sources were tested. For a period of 8.5 years, we computed daily forecasts with a lead time of +120 h based on an empirically downscaled version of the ECMWF's ensemble prediction system. For the last 3.5 years of the test period, we also tried the deterministic COSMO-EU forecast disseminated by the German Weather Service for lead times of up to +72 h. Common measures of skill indicate superiority of the ensemble runoff forecast over single-value forecasts for longer lead times. However, regardless of which NWP data were being used, the probability of event detection (POD) was found to be generally lower than 50\%. In many cases, values in the range of 20-30\% were obtained. At the same time, the false alarms ratio (FAR) was often found to be considerably high. The observed uncertainties in the hydrological forecasts were shown to originate from both the insufficient quality of precipitation forecasts as well as deficiencies in hydrological modeling and quantitative precipitation estimation. With respect to the anticipatory control of reservoirs in the studied catchment, the value of the tested runoff forecasts appears to be limited. This is due to the unfavorably low POD/FAR ratio in conjunction with a high cost-loss ratio. However, our results indicate that, in many cases, major runoff events related to snow melt can be successfully predicted as early as 4-5 days in advance.}, language = {en} } @article{CostaBronstertKneis2012, author = {Costa, Alexandre Cunha and Bronstert, Axel and Kneis, David}, title = {Probabilistic flood forecasting for a mountainous headwater catchment using a nonparametric stochastic dynamic approach}, series = {Hydrological sciences journal = Journal des sciences hydrologiques}, volume = {57}, journal = {Hydrological sciences journal = Journal des sciences hydrologiques}, number = {1}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0262-6667}, doi = {10.1080/02626667.2011.637043}, pages = {10 -- 25}, year = {2012}, abstract = {Hydrological models are commonly used to perform real-time runoff forecasting for flood warning. Their application requires catchment characteristics and precipitation series that are not always available. An alternative approach is nonparametric modelling based only on runoff series. However, the following questions arise: Can nonparametric models show reliable forecasting? Can they perform as reliably as hydrological models? We performed probabilistic forecasting one, two and three hours ahead for a runoff series, with the aim of ascribing a probability density function to predicted discharge using time series analysis based on stochastic dynamics theory. The derived dynamic terms were compared to a hydrological model, LARSIM. Our procedure was able to forecast within 95\% confidence interval 1-, 2- and 3-h ahead discharge probability functions with about 1.40 m(3)/s of range and relative errors (\%) in the range [-30; 30]. The LARSIM model and the best nonparametric approaches gave similar results, but the range of relative errors was larger for the nonparametric approaches.}, language = {en} } @article{BronstertEngel2005, author = {Bronstert, Axel and Engel, H.}, title = {Ver{\"a}nderung der Abfl{\"u}sse}, series = {Warnsignal Klima - genug Wasser f{\"u}r alle? : wissenschaftliche Fakten}, journal = {Warnsignal Klima - genug Wasser f{\"u}r alle? : wissenschaftliche Fakten}, publisher = {Wissenschaftliche Auswertungen}, address = {Hamburg}, isbn = {978-3-9809668-0-1}, pages = {175 -- 181}, year = {2005}, language = {de} } @article{Bronstert2004, author = {Bronstert, Axel}, title = {Rainfall-runoff modelling for assessing impacts of climate and land-use change}, year = {2004}, language = {en} } @article{PfisterKwadijkMusyetal.2003, author = {Pfister, L. and Kwadijk, J. and Musy, A. and Bronstert, Axel and Hoffmann, L.}, title = {Climate change, land use change and run-off prediction in the Rhine-Meuse basins}, issn = {1535-1459}, year = {2003}, abstract = {As a consequence of increasing winter rainfall totals and intensities over the second half of the 20th century, signs of increased flooding probability in many areas of the Rhine and Meuse basins have been documented. These changes affecting rainfall characteristics are most evidently due to an increase in westerly atmospheric circulation types. Land use changes, particularly urbanization, can have significant local effects in small basins (headwaters) with respect to flooding, especially during heavy local rainstorms, but no evidence exists that land use change has had significant effects on peak flows in the rivers Rhine and Meuse. For the 21st century, most global circulation models suggest higher winter rainfall totals. Most hydrological simulations of the Rhine-Meuse river basins suggest an increased flooding probability, with a progressive shift of the Rhine from a 'rain-fed/meltwater' river into a mainly 'rain-fed' river. A very limited effect of changes in land use on the discharge regime seems to exist for the main branches of the Meuse and Rhine rivers. For mesoscale basins, future changes in peak flows depend on the changes in the variability of extreme precipitations in combination with land use changes. Copyright (C) 2004 John Wiley Sons, Ltd}, language = {en} } @article{MenzelNiehoffBuergeretal.2002, author = {Menzel, Lucas and Niehoff, Daniel and B{\"u}rger, Gerd and Bronstert, Axel}, title = {Climate change impacts on river flooding : a modelling study of three meso-scale catchments}, year = {2002}, language = {en} } @article{BronstertNiehoffBuerger2002, author = {Bronstert, Axel and Niehoff, Daniel and B{\"u}rger, Gerd}, title = {Effects of climate and land-use change on storm runoff generation : present knowledge and modelling capabilities}, year = {2002}, language = {en} } @article{GuentnerBronstert2004, author = {G{\"u}ntner, Andreas and Bronstert, Axel}, title = {Representation of landscape variability and lateral redistribution processes for large-scale hydrological modelling in semi-arid areas}, issn = {0022-1694}, year = {2004}, abstract = {The spatial variability of landscape features such as topography, soils and vegetation defines the spatial pattern of hydrological state variables like soil moisture. Spatial variability thereby controls the functional behaviour of the landscape in terms of its runoff response. A consequence of spatial variability is that exchange processes between landscape patches can occur at various spatial scales ranging from the plot to the basin scale. In semi-arid areas, the lateral redistribution of surface runoff between adjacent landscape patches is an important process. For applications to large river basins of 10(4)-10(5) km(2) in size, a multi-scale landscape discretization scheme is presented in this paper. The landscape is sub-divided into modelling units within a hierarchy of spatial scale levels. By delineating areas characterized by a typical toposequence, organised and random variability of landscape characteristics is captured in the model. Using runoff-runon relationships with transition frequencies based on areal fractions of modelling units, lateral surface and subsurface water fluxes between modelling units at the hillslope scale are represented. Thus, the new approach allows for a manageable description of interactions between fine-scale landscape features for inclusion in coarse-scale models. Model applications for the State of Ceara (148,000 km(2)) in the north- east of Brazil demonstrate the importance of taking into account landscape variability and interactions between landscape patches in a semi-arid environment. Using mean landscape characteristics leads to a considerable underestimation of infiltration-excess surface runoff and total simulated runoff. Re-infiltration of surface runoff and lateral redistribution processes between landscape patches cause a reduction of runoff volumes at the basin scale and contribute to the amplification of variations in runoff volumes relative to variations in rainfall volumes for semi-arid areas. (C) 2004 Elsevier B.V. All rights reserved}, language = {en} } @article{BronstertKrolJaegeretal.2002, author = {Bronstert, Axel and Krol, Marten S. and Jaeger, Annekathrin and G{\"u}ntner, Andreas}, title = {Integrated modelling of climate, water, soil, agricultural and socio-economic processes : a general introduction to the methodology and some exemplary results from the semi-arid Northeast of Brazil}, year = {2002}, language = {en} } @article{GuentnerBronstert2002, author = {G{\"u}ntner, Andreas and Bronstert, Axel}, title = {Process-based modelling of large-scale water availability in a semi-arid environment : process representation and scaling issues}, year = {2002}, language = {en} } @article{NiehoffFritschBronstert2002, author = {Niehoff, Daniel and Fritsch, Uta and Bronstert, Axel}, title = {Land-use impacts on storm-runoff generation : scenarios of land-use change and simulation of hydrological response in a meso-scale catchment in SW-Germany}, year = {2002}, language = {en} } @article{NiehoffBronstert2002, author = {Niehoff, Daniel and Bronstert, Axel}, title = {Landnutzung und Hochwasserentstehung : Modellierung anhand dreier mesoskaliger Einzugsgebiete}, year = {2002}, language = {de} } @article{BronstertMenzel2002, author = {Bronstert, Axel and Menzel, Lucas}, title = {Advances in Flood Research}, year = {2002}, language = {en} } @article{MtilatilaBronstertVormoor2022, author = {Mtilatila, Lucy Mphatso Ng'ombe and Bronstert, Axel and Vormoor, Klaus Josef}, title = {Temporal evaluation and projections of meteorological droughts in the Greater Lake Malawi Basin, Southeast Africa}, series = {Frontiers in Water}, journal = {Frontiers in Water}, publisher = {Frontiers Media S.A.}, address = {Lausanne, Schweiz}, issn = {2624-9375}, doi = {10.3389/frwa.2022.1041452}, pages = {1 -- 16}, year = {2022}, abstract = {The study examined the potential future changes of drought characteristics in the Greater Lake Malawi Basin in Southeast Africa. This region strongly depends on water resources to generate electricity and food. Future projections (considering both moderate and high emission scenarios) of temperature and precipitation from an ensemble of 16 bias-corrected climate model combinations were blended with a scenario-neutral response surface approach to analyses changes in: (i) the meteorological conditions, (ii) the meteorological water balance, and (iii) selected drought characteristics such as drought intensity, drought months, and drought events, which were derived from the Standardized Precipitation and Evapotranspiration Index. Changes were analyzed for a near-term (2021-2050) and far-term period (2071-2100) with reference to 1976-2005. The effect of bias-correction (i.e., empirical quantile mapping) on the ability of the climate model ensemble to reproduce observed drought characteristics as compared to raw climate projections was also investigated. Results suggest that the bias-correction improves the climate models in terms of reproducing temperature and precipitation statistics but not drought characteristics. Still, despite the differences in the internal structures and uncertainties that exist among the climate models, they all agree on an increase of meteorological droughts in the future in terms of higher drought intensity and longer events. Drought intensity is projected to increase between +25 and +50\% during 2021-2050 and between +131 and +388\% during 2071-2100. This translates into +3 to +5, and +7 to +8 more drought months per year during both periods, respectively. With longer lasting drought events, the number of drought events decreases. Projected droughts based on the high emission scenario are 1.7 times more severe than droughts based on the moderate scenario. That means that droughts in this region will likely become more severe in the coming decades. Despite the inherent high uncertainties of climate projections, the results provide a basis in planning and (water-)managing activities for climate change adaptation measures in Malawi. This is of particular relevance for water management issues referring hydro power generation and food production, both for rain-fed and irrigated agriculture.}, language = {en} } @article{PilzDelgadoVossetal.2019, author = {Pilz, Tobias and Delgado, Jos{\´e} Miguel Martins and Voss, Sebastian and Vormoor, Klaus Josef and Francke, Till and Cunha Costa, Alexandre and Martins, Eduardo and Bronstert, Axel}, title = {Seasonal drought prediction for semiarid northeast Brazil}, series = {Hydrology and Earth System Sciences}, volume = {23}, journal = {Hydrology and Earth System Sciences}, publisher = {Copernicus Publications}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-23-1951-2019}, pages = {1951 -- 1971}, year = {2019}, abstract = {The semiarid northeast of Brazil is one of the most densely populated dryland regions in the world and recurrently affected by severe droughts. Thus, reliable seasonal forecasts of streamflow and reservoir storage are of high value for water managers. Such forecasts can be generated by applying either hydrological models representing underlying processes or statistical relationships exploiting correlations among meteorological and hydrological variables. This work evaluates and compares the performances of seasonal reservoir storage forecasts derived by a process-based hydrological model and a statistical approach. Driven by observations, both models achieve similar simulation accuracies. In a hindcast experiment, however, the accuracy of estimating regional reservoir storages was considerably lower using the process-based hydrological model, whereas the resolution and reliability of drought event predictions were similar by both approaches. Further investigations regarding the deficiencies of the process-based model revealed a significant influence of antecedent wetness conditions and a higher sensitivity of model prediction performance to rainfall forecast quality. Within the scope of this study, the statistical model proved to be the more straightforward approach for predictions of reservoir level and drought events at regionally and monthly aggregated scales. However, for forecasts at finer scales of space and time or for the investigation of underlying processes, the costly initialisation and application of a process-based model can be worthwhile. Furthermore, the application of innovative data products, such as remote sensing data, and operational model correction methods, like data assimilation, may allow for an enhanced exploitation of the advanced capabilities of process-based hydrological models.}, language = {en} } @article{NiehoffBronstert2000, author = {Niehoff, Daniel and Bronstert, Axel}, title = {Influences of land-use and land-surface conditions on flood generation : a simulation study}, year = {2000}, language = {en} } @article{HuangHattermannKrysanovaetal.2013, author = {Huang, Shaochun and Hattermann, Fred and Krysanova, Valentina and Bronstert, Axel}, title = {Projections of climate change impacts on river flood conditions in Germany by combining three different RCMs with a regional eco-hydrological model}, series = {Climatic change : an interdisciplinary, intern. journal devoted to the description, causes and implications of climatic change}, volume = {116}, journal = {Climatic change : an interdisciplinary, intern. journal devoted to the description, causes and implications of climatic change}, number = {3-4}, publisher = {Springer}, address = {Dordrecht}, issn = {0165-0009}, doi = {10.1007/s10584-012-0586-2}, pages = {631 -- 663}, year = {2013}, abstract = {A general increase in precipitation has been observed in Germany in the last century, and potential changes in flood generation and intensity are now at the focus of interest. The aim of the paper is twofold: a) to project the future flood conditions in Germany accounting for various river regimes (from pluvial to nival-pluvial regimes) and under different climate scenarios (the high, A2, low, B1, and medium, A1B, emission scenarios) and b) to investigate sources of uncertainty generated by climate input data and regional climate models. Data of two dynamical Regional Climate Models (RCMs), REMO (REgional Model) and CCLM (Cosmo-Climate Local Model), and one statistical-empirical RCM, Wettreg (Wetterlagenbasierte Regionalisierungsmethode: weather-type based regionalization method), were applied to drive the eco-hydrological model SWIM (Soil and Water Integrated Model), which was previously validated for 15 gauges in Germany. At most of the gauges, the 95 and 99 percentiles of the simulated discharge using SWIM with observed climate data had a good agreement with the observed discharge for 1961-2000 (deviation within +/- 10 \%). However, the simulated discharge had a bias when using RCM climate as input for the same period. Generalized Extreme Value (GEV) distributions were fitted to the annual maximum series of river runoff for each realization for the control and scenario periods, and the changes in flood generation over the whole simulation time were analyzed. The 50-year flood values estimated for two scenario periods (2021-2060, 2061-2100) were compared to the ones derived from the control period using the same climate models. The results driven by the statistical-empirical model show a declining trend in the flood level for most rivers, and under all climate scenarios. The simulations driven by dynamical models give various change directions depending on region, scenario and time period. The uncertainty in estimating high flows and, in particular, extreme floods remains high, due to differences in regional climate models, emission scenarios and multi-realizations generated by RCMs.}, language = {en} } @article{GraeffZeheReusseretal.2009, author = {Gr{\"a}ff, Thomas and Zehe, Erwin and Reusser, Dominik and Lueck, Erika and Schroeder, Boris and Wenk, Gerald and John, Hermann and Bronstert, Axel}, title = {Process identification through rejection of model structures in a mid-mountainous rural catchment : observations of rainfall-runoff response, geophysical conditions and model inter-comparison}, issn = {0885-6087}, doi = {10.1002/Hyp.7171}, year = {2009}, abstract = {The intention of the presented study is to gain a better understanding of the mechanisms that caused the bimodal rainfall-runoff responses which occurred up to the mid-1970s regularly in the Schafertal catchment and vanished after the onset of mining activities. Understanding, this process is a first step to understanding the ongoing hydrological change in this area. It is hypothesized that either subsurface stormflow, or fast displacement of groundwater, could cause the second delayed peak. A top-down analysis of rainfall-runoff data, field observations as well as process modelling are combined within a rejectionistic framework. A statistical analysis is used to test whether different predictors. which characterize the forcing. near surface water content and deeper subsurface store, allow the prediction of the type of rainfall-runoff response. Regression analysis is used with generalized linear models Lis they can deal with non-Gaussian error distributions Lis well its a non-stationary variance. The analysis reveals that the dominant predictors are the pre-event discharge (proxy of state of the groundwater store) and the precipitation amount, In the field campaign, the subsurface at a representative hillslope was investigated by means of electrical resistivity tomography in order to identify possible strata as flow paths for subsurface stormflow. A low resistivity in approximately 4 in depth-either due to a less permeable layer or the groundwater surface-was detected. The former Could serve as a flow path for subsurface stormflow. Finally, the physical-based hydrological model CATFLOW and the groundwater model FEFLOW are compared with respect to their ability to reproduce the bimodal runoff responses. The groundwater model is able to reproduce the observations, although it uses only an abstract representation of the hillslopes. Process model analysis as well Lis statistical analysis strongly suggest that fast displacement of groundwater is the dominant process underlying the bimodal runoff reactions.}, language = {en} } @article{BrosinskyFoersterSegletal.2014, author = {Brosinsky, Arlena and F{\"o}rster, Saskia and Segl, Karl and Lopez-Tarazon, Jos{\´e} Andr{\´e}s and Pique, Gemma and Bronstert, Axel}, title = {Spectral fingerprinting: characterizing suspended sediment sources by the use of VNIR-SWIR spectral information}, series = {Journal of soils and sediments : protection, risk assessment and remediation}, volume = {14}, journal = {Journal of soils and sediments : protection, risk assessment and remediation}, number = {12}, publisher = {Springer}, address = {Heidelberg}, issn = {1439-0108}, doi = {10.1007/s11368-014-0927-z}, pages = {1965 -- 1981}, year = {2014}, abstract = {Knowledge of sediment sources is a prerequisite for sustainable management practices and may furthermore improve our understanding of water and sediment fluxes. Investigations have shown that a number of characteristic soil properties can be used as "fingerprints" to trace back the sources of river sediments. Spectral properties have recently been successfully used as such characteristics in fingerprinting studies. Despite being less labour-intensive than geochemical analyses, for example, spectroscopy allows measurements of small amounts of sediment material (> 60 mg), thus enabling inexpensive analyses even of intra-event variability. The focus of this study is on the examination of spectral properties of fluvial sediment samples to detect changes in source contributions, both between and within individual flood events. Sediment samples from the following three different origins were collected in the Isabena catchment (445 km(2)) in the central Spanish Pyrenees: (1) soil samples from the main potential source areas, (2) stored fine sediment from the channel bed once each season in 2011 and (3) suspended sediment samples during four flood events in autumn 2011 and spring 2012 at the catchment outlet as well as at several subcatchment outlets. All samples were dried and measured for spectral properties in the laboratory using an ASD spectroradiometer. Colour parameters and physically based features (e.g. organic carbon, iron oxide and clay content) were calculated from the spectra. Principal component analyses (PCA) were applied to all three types of samples to determine natural clustering of samples, and a mixing model was applied to determine source contributions. We found that fine sediment stored in the river bed seems to be mainly influenced by grain size and seasonal variability, while sampling location-and thus the effect of individual tributaries or subcatchments-seem to be of minor importance. Suspended sediment sources were found to vary between, as well as within, flood events; although badlands were always the major source. Forests and grasslands contributed little (< 10 \%), and other sources (not further determinable) contributed up to 40 \%. The analyses further suggested that sediment sources differ among the subcatchments and that subcatchments comprising relatively large proportions of badlands contributed most to the four flood events analyzed. Spectral fingerprints provide a rapid and cost-efficient alternative to conventional fingerprint properties. However, a combination of spectral and conventional fingerprint properties could potentially permit discrimination of a larger number of source types.}, language = {en} } @article{RottlerKormannFranckeetal.2018, author = {Rottler, Erwin and Kormann, Christoph Martin and Francke, Till and Bronstert, Axel}, title = {Elevation-dependent warming in the Swiss Alps 1981-2017}, series = {International journal of climatology : a journal of the Royal Meteorological Society}, volume = {39}, journal = {International journal of climatology : a journal of the Royal Meteorological Society}, number = {5}, publisher = {Wiley}, address = {Hoboken}, issn = {0899-8418}, doi = {10.1002/joc.5970}, pages = {2556 -- 2568}, year = {2018}, abstract = {Due to the environmental and socio-economic importance of mountainous regions, it is crucial to understand causes and consequences of climatic changes in those sensitive landscapes. Daily resolution alpine climate data from Switzerland covering an elevation range of over 3,000m between 1981 and 2017 have been analysed using highly resolved trends in order to gain a better understanding of features, forcings and feedbacks related to temperature changes in mountainous regions. Particular focus is put on processes related to changes in weather types, incoming solar radiation, cloud cover, air humidity, snow/ice and elevation dependency of temperature trends. Temperature trends in Switzerland differ depending on the time of the year, day and elevation. Warming is strongest during spring and early summer with enhanced warming of daytime maximum temperatures. Elevation-based differences in temperature trends occur during autumn and winter with stronger warming at lower elevations. We attribute this elevation-dependent temperature signal mainly to elevation-based differences in trends of incoming solar radiation and elevation-sensitive responses to changes in frequencies of weather types. In general, effects of varying frequencies of weather types overlap with trends caused by transmission changes in short- and long-wave radiation. Temperature signals arising from snow/ice albedo feedback mechanisms are probably small and might be hidden by other effects.}, language = {en} } @misc{LopezTarazonBronstertThiekenetal.2019, author = {Lopez Tarazon, Jos{\´e} Andr{\´e}s and Bronstert, Axel and Thieken, Annegret and Petrow, Theresia}, title = {The effects of global change on floods, fluvial geomorphology and related hazards in mountainous rivers}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {669}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2019.03.026}, pages = {7 -- 10}, year = {2019}, language = {en} } @book{BronstertSeiertOberholzer1993, author = {Bronstert, Axel and Seiert, S. and Oberholzer, Gustav}, title = {Maßnahmen der Flurbereinigung und ihre Wirkung auf das Abflußverhalten l{\"a}ndlicher Gebiete : gemeinsamer Bericht des Instituts f{\"u}r Hydrologie und Wasserwirtschaft, Universit{\"a}t Karlsruhe, und des Instituts f{\"u}r Liegenschaftswesen, Planung und Bodenordnung, Universit{\"a}t der Bundeswehr, Neubiberg bei M{\"u}nchen}, series = {Flurneuordnung und Landentwicklung Baden W{\"u}rttemberg}, volume = {3}, journal = {Flurneuordnung und Landentwicklung Baden W{\"u}rttemberg}, publisher = {LfU}, address = {Karlsruhe}, pages = {145 S.}, year = {1993}, language = {de} } @article{BronstertKneisBogena2009, author = {Bronstert, Axel and Kneis, David and Bogena, Heye R.}, title = {Interactions and feedbacks in hydrological change : relevance and possibilities of modelling}, issn = {1439-1783}, year = {2009}, abstract = {The hydrological cycle is a dynamic system by its nature, but sometimes accelerated through anthropogenic activity. A "hydrological change" (i.e. a water cycle that is significantly changing over a longer period of time) can be very different in character, depending on the specific natural conditions and the underlying spatial and temporal scales. Such changes may affect the availability and quality of water as essential pre-requisites for human development and ecosystem stability. Hydrological extremes, such as floods and droughts, may also be affected, what is also vitally important, because of their profound economic and societal impacts. Anthropogenically induced hydrological change can be attributed to three main external causes: first, the Earth's climate is changing significantly and thus directly affecting the terrestrial hydro-systems via the exchange of energy and heat. The second major issue is the land cover and its management that has been modified fundamentally by conversion of land for agriculture, forestry, and other purposes such as industrialisation and urbanisation. Finally, water resources are being used more than ever for human development, especially for agriculture, industrial activities, and navigation. If the regional terrestrial hydrological cycle is changing and counter-measures are desirable, it is from a scientific perspective mandatory to understand the extent and nature of such changes, and, especially, to identify their possible anthropogenic origin. There are, however, fundamental gaps in our knowledge, in particular about the role of feedbacks between individual processes and compartments of the hydrological cycle or the relevance of the interactions with other sub-systems of our planet, such as the atmosphere or the vegetation. This paper mentions several examples of hydrological change and discusses their identification, interaction processes, and feedback mechanisms, along with modelling issues. The possibilities and limitations of modelling are demonstrated by means of two studies: one from the river-lake system on the Middle-Havel River and one from the catchment of the Wahnbach Reservoir. The applied model systems comprise a series of consecutively coupled individual models (so-called one-way-coupling). Model systems that are able reflect feedback effects (two-way- coupling) are still in the development stage. It became clear that the applied model systems were able to reproduce the observed dynamics of the hydrological cycle and of selected matter fluxes. However, one has to be aware that the simulated time periods and scenarios represent rather moderately transient conditions, what is the justification why the one-way-coupling seems to be applicable. Furthermore, it was shown that the modelling uncertainty is considerably large. Nevertheless, this uncertainty can be distinguished from effects of changed internal systems dynamics or from changed boundary conditions, what is a basis for the usability of such model systems for prognostic purposes.}, language = {en} } @article{BreuerWillemsBormannetal.2009, author = {Breuer, Lutz and Willems, Patrick and Bormann, Helge and Bronstert, Axel and Croke, Barry and Frede, Hans Georg and Gr{\"a}ff, Thomas and Hubrechts, Lode and Kite, Geoffrey and Lanini, Jordan and Leavesley, George and Lettenmaier, Dennis P. and Lindstroem, Goeran and Seibert, Jan and Sivapalan, Mayuran and Viney, Neil R.}, title = {Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) : I: model intercomparison with current land use}, issn = {0309-1708}, doi = {10.1016/j.advwatres.2008.10.003}, year = {2009}, abstract = {This paper introduces the project on 'Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM)' that aims at investigating the envelope of predictions on changes in hydrological fluxes due to land use change. As part of a series of four papers, this paper outlines the motivation and setup of LUCHEM, and presents a model intercomparison for the present-day simulation results. Such an intercomparison provides a valuable basis to investigate the effects of different model structures on model predictions and paves the ground for the analysis of the performance of multi-model ensembles and the reliability of the scenario predictions in companion papers. in this study, we applied a set of 10 lumped, semi-lumped and fully distributed hydrological models that have been previously used in land use change studies to the low mountainous Dill catchment. Germany. Substantial differences in model performance were observed with Nash-Sutcliffe efficiencies ranging from 0.53 to 0.92. Differences in model performance were attributed to (1) model input data, (2) model calibration and (3) the physical basis of the models. The models were applied with two sets of input data: an original and a homogenized data set. This homogenization of precipitation, temperature and leaf area index was performed to reduce the variation between the models. Homogenization improved the comparability of model simulations and resulted in a reduced average bias, although some variation in model data input remained. The effect of the physical differences between models on the long-term water balance was mainly attributed to differences in how models represent evapotranspiration. Semi-lumped and lumped conceptual models slightly outperformed the fully distributed and physically based models. This was attributed to the automatic model calibration typically used for this type of models. Overall, however, we conclude that there was no superior model if several measures of model performance are considered and that all models are suitable to participate in further multi-model ensemble set-ups and land use change scenario investigations.}, language = {en} } @article{KneisFoersterBronstert2009, author = {Kneis, David and F{\"o}rster, Saskia and Bronstert, Axel}, title = {Simulation of water quality in a flood detention area using models of different spatial discretization}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2009.04.006}, year = {2009}, abstract = {Detention areas provide a means to lower peak discharges in rivers by temporarily storing excess water. In the case of extreme flood events, the storage effect reduces the risk of dike failures or extensive inundations for downstream reaches and near the site of abstraction. Due to the large amount of organic matter contained in the river water and the inundation of terrestrial vegetation in the detention area, a deterioration of water quality may occur. In particular, decay processes can cause a severe depletion of dissolved oxygen (DO) in the temporary water body. In this paper, we studied the potential of a water quality model to simulate the DO dynamics in a large but shallow detention area to be built at the Elbe River (Germany). Our focus was on examining the impact of spatial discretization on the model's performance and usability. Therefore, we used a zero-dimensional (OD) and a two-dimensional (2D) modeling approach in parallel. The two approaches solely differ in their spatial discretization, while conversion processes, parameters, and boundary conditions were kept identical. The dynamics of DO simulated by the two models are similar in the initial flooding period but diverge when the system starts to drain. The deviation can be attributed to the different spatial discretization of the two models, leading to different estimates of flow velocities and water depths. Only the 2D model can account for the impact of spatial variability on the evolution of state variables. However, its application requires high efforts for pre- and post-processing and significantly longer computation times. The 2D model is, therefore, not suitable for investigating various flood scenarios or for analyzing the impact of parameter uncertainty. For practical applications, we recommend to firstly set up a fast-running model of reduced spatial discretization, e.g. a OD model. Using this tool, the reliability of the simulation results should be checked by analyzing the parameter uncertainty of the water quality model. A particular focus may be on those parameters that are spatially variable and, therefore, believed to be better represented in a 2D approach. The benefit from the application of the more costly 2D model should be assessed, based on the analyses carried out with the OD model. A 2D model appears to be preferable only if the simulated detention area has a complex topography, flow velocities are highly variable in space, and the parameters of the water quality model are well known.}, language = {en} } @article{BronstertKneisBogena2009, author = {Bronstert, Axel and Kneis, David and Bogena, Heye R.}, title = {Interaktionen und R{\"u}ckkopplungen beim hydrologischen Wandel : Relevanz und M{\"o}glichkeiten der Modellierung}, issn = {1439-1783}, year = {2009}, language = {de} } @article{MedeirosdeAraujoBronstert2009, author = {Medeiros, Pedro Henrique Augusto and de Araujo, Jose Carlos and Bronstert, Axel}, title = {Interception measurements and assessment of Gash model performance for a tropical semi-arid region}, issn = {0045-6888}, year = {2009}, abstract = {Semi-arid environments usually face water scarcity and conflicts for its use; therefore a complete understanding of the water balance in these regions is desired. To evaluate interception, measurements of precipitation, throughfall and stemflow were carried out in a Brazilian tropical semi-arid experimental watershed with well preserved Caatinga vegetation. Data analysis indicates that interception losses correspond to 13\% of total rainfall, representing an important process in the watershed's water balance, where runoff is only 6\% of total precipitation. Gash interception model was applied in the region with good results for long term simulation. Nevertheless, the model produced significant but not systematic errors on a daily basis. This was attributed to its incapability of representing the temporal variation of precipitation during the event, which is a major factor affecting interception. Rainfall intensity was shown to be a good parameter to determine an applicability threshold for Gash model in the study area.}, language = {en} } @article{MiegelGraeffFrancketal.2017, author = {Miegel, Konrad and Gr{\"a}ff, Thomas and Franck, Christian and Salzmann, Thomas and Bronstert, Axel and Walther, Marc and Oswald, Sascha}, title = {Auswirkungen des Sturmhochwassers der Ostsee am 4./5. Januar 2017 auf das renaturierte Nieder- moor „H{\"u}telmoor und Heiligensee" an der deut- schen Ostseek{\"u}ste}, series = {Hydrologie und Wasserbewirtschaftung}, volume = {61}, journal = {Hydrologie und Wasserbewirtschaftung}, number = {4}, publisher = {Bundesanst. f{\"u}r Gew{\"a}sserkunde}, address = {Koblenz}, issn = {1439-1783}, doi = {10.5675/HyWa_2017,4_2}, pages = {232 -- 243}, year = {2017}, abstract = {Entlang der K{\"u}stenniederung des Naturschutzgebietes „H{\"u}telmoor und Heiligensee", ca. 6 km nord{\"o}stlich von Rostock-Warnem{\"u}nde gelegen, wird seit dem Jahr 2000 die K{\"u}stend{\"u}ne nicht mehr instand gehalten. Im Rahmen der Renaturierung des Gebietes werden so grunds{\"a}tzlich wieder {\"U}berflutungen bei Ostseehochwassern zugelassen, was bisher jedoch noch nicht eingetreten ist. Am 4./5. Januar 2017 ereignete sich ein Sturmhochwasser der Ostsee, mit einem Scheitelwasserstand in Warnem{\"u}nde, der sich zwischen dem 10- und 20-j{\"a}hrlichen Hochwasserstand einordnet. Dennoch kam es bei diesem Ereignis nicht zum D{\"u}nendurchbruch und zur seeseitigen {\"U}berflutung, wohl aber zum binnenseitigen Einstrom von Salz- bzw. Brackwasser. Dieser erfolgte {\"u}ber den Graben, durch den das Gebiet normalerweise {\"u}ber die Warnow in die Ostsee entw{\"a}ssert. Durch das Einstr{\"o}men {\"u}ber die Sohlschwelle, sonst Auslass des Gebietes, stiegen die Wasserst{\"a}nde und Salzkonzentrationen in der s{\"u}dwestlichen H{\"a}lfte der Niederung an. Mit zunehmender Entfernung zur Sohlschwelle waren diese Auswirkungen jedoch geringer sp{\"u}rbar. Dies gilt wegen der Retentionswirkung der Niederung mehr f{\"u}r den Wasserstand als f{\"u}r die Salzkonzentration. W{\"a}hrend der Wasserstand durch den Einstau der Niederung und {\"U}berschwemmungen fl{\"a}chenhaft anstieg, breitete sich die Salzfront pr{\"a}ferentiell in den ehemaligen Entw{\"a}sserungsgr{\"a}ben, die trotz des Einstaus nach wie vor hydraulisch aktiv sind, eher linienhaft aus. Diese Interpretation beruht auf Messergebnissen von Wasserstand, elektrischer Leitf{\"a}higkeit und Wassertemperatur.}, language = {de} } @misc{MtilatilaBronstertVormoor2022, author = {Mtilatila, Lucy Mphatso Ng'ombe and Bronstert, Axel and Vormoor, Klaus Josef}, title = {Temporal evaluation and projections of meteorological droughts in the Greater Lake Malawi Basin, Southeast Africa}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1287}, issn = {1866-8372}, doi = {10.25932/publishup-57128}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-571284}, pages = {16}, year = {2022}, abstract = {The study examined the potential future changes of drought characteristics in the Greater Lake Malawi Basin in Southeast Africa. This region strongly depends on water resources to generate electricity and food. Future projections (considering both moderate and high emission scenarios) of temperature and precipitation from an ensemble of 16 bias-corrected climate model combinations were blended with a scenario-neutral response surface approach to analyses changes in: (i) the meteorological conditions, (ii) the meteorological water balance, and (iii) selected drought characteristics such as drought intensity, drought months, and drought events, which were derived from the Standardized Precipitation and Evapotranspiration Index. Changes were analyzed for a near-term (2021-2050) and far-term period (2071-2100) with reference to 1976-2005. The effect of bias-correction (i.e., empirical quantile mapping) on the ability of the climate model ensemble to reproduce observed drought characteristics as compared to raw climate projections was also investigated. Results suggest that the bias-correction improves the climate models in terms of reproducing temperature and precipitation statistics but not drought characteristics. Still, despite the differences in the internal structures and uncertainties that exist among the climate models, they all agree on an increase of meteorological droughts in the future in terms of higher drought intensity and longer events. Drought intensity is projected to increase between +25 and +50\% during 2021-2050 and between +131 and +388\% during 2071-2100. This translates into +3 to +5, and +7 to +8 more drought months per year during both periods, respectively. With longer lasting drought events, the number of drought events decreases. Projected droughts based on the high emission scenario are 1.7 times more severe than droughts based on the moderate scenario. That means that droughts in this region will likely become more severe in the coming decades. Despite the inherent high uncertainties of climate projections, the results provide a basis in planning and (water-)managing activities for climate change adaptation measures in Malawi. This is of particular relevance for water management issues referring hydro power generation and food production, both for rain-fed and irrigated agriculture.}, language = {en} } @misc{SeleemAyzelCostaTomazdeSouzaetal.2022, author = {Seleem, Omar and Ayzel, Georgy and Costa Tomaz de Souza, Arthur and Bronstert, Axel and Heistermann, Maik}, title = {Towards urban flood susceptibility mapping using data-driven models in Berlin, Germany}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1297}, issn = {1866-8372}, doi = {10.25932/publishup-57680}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-576806}, pages = {1640 -- 1662}, year = {2022}, abstract = {Identifying urban pluvial flood-prone areas is necessary but the application of two-dimensional hydrodynamic models is limited to small areas. Data-driven models have been showing their ability to map flood susceptibility but their application in urban pluvial flooding is still rare. A flood inventory (4333 flooded locations) and 11 factors which potentially indicate an increased hazard for pluvial flooding were used to implement convolutional neural network (CNN), artificial neural network (ANN), random forest (RF) and support vector machine (SVM) to: (1) Map flood susceptibility in Berlin at 30, 10, 5, and 2 m spatial resolutions. (2) Evaluate the trained models' transferability in space. (3) Estimate the most useful factors for flood susceptibility mapping. The models' performance was validated using the Kappa, and the area under the receiver operating characteristic curve (AUC). The results indicated that all models perform very well (minimum AUC = 0.87 for the testing dataset). The RF models outperformed all other models at all spatial resolutions and the RF model at 2 m spatial resolution was superior for the present flood inventory and predictor variables. The majority of the models had a moderate performance for predictions outside the training area based on Kappa evaluation (minimum AUC = 0.8). Aspect and altitude were the most influencing factors on the image-based and point-based models respectively. Data-driven models can be a reliable tool for urban pluvial flood susceptibility mapping wherever a reliable flood inventory is available.}, language = {en} } @misc{SeleemAyzelBronstertetal.2023, author = {Seleem, Omar and Ayzel, Georgy and Bronstert, Axel and Heistermann, Maik}, title = {Transferability of data-driven models to predict urban pluvial flood water depth in Berlin, Germany}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1323}, issn = {1866-8372}, doi = {10.25932/publishup-58916}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-589168}, pages = {809 -- 822}, year = {2023}, abstract = {Data-driven models have been recently suggested to surrogate computationally expensive hydrodynamic models to map flood hazards. However, most studies focused on developing models for the same area or the same precipitation event. It is thus not obvious how transferable the models are in space. This study evaluates the performance of a convolutional neural network (CNN) based on the U-Net architecture and the random forest (RF) algorithm to predict flood water depth, the models' transferability in space and performance improvement using transfer learning techniques. We used three study areas in Berlin to train, validate and test the models. The results showed that (1) the RF models outperformed the CNN models for predictions within the training domain, presumable at the cost of overfitting; (2) the CNN models had significantly higher potential than the RF models to generalize beyond the training domain; and (3) the CNN models could better benefit from transfer learning technique to boost their performance outside training domains than RF models.}, language = {en} } @misc{RottlerFranckeBuergeretal.2020, author = {Rottler, Erwin and Francke, Till and B{\"u}rger, Gerd and Bronstert, Axel}, title = {Long-term changes in central European river discharge for 1869-2016}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {4}, issn = {1866-8372}, doi = {10.25932/publishup-51776}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-517763}, pages = {22}, year = {2020}, abstract = {Recent climatic changes have the potential to severely alter river runoff, particularly in snow-dominated river basins. Effects of changing snow covers superimpose with changes in precipitation and anthropogenic modifications of the watershed and river network. In the attempt to identify and disentangle long-term effects of different mechanisms, we employ a set of analytical tools to extract long-term changes in river runoff at high resolution. We combine quantile sampling with moving average trend statistics and empirical mode decomposition and apply these tools to discharge data recorded along rivers with nival, pluvial and mixed flow regimes as well as temperature and precipitation data covering the time frame 1869-2016. With a focus on central Europe, we analyse the long-term impact of snow cover and precipitation changes along with their interaction with reservoir constructions. Our results show that runoff seasonality of snow-dominated rivers decreases. Runoff increases in winter and spring, while discharge decreases in summer and at the beginning of autumn. We attribute this redistribution of annual flow mainly to reservoir constructions in the Alpine ridge. During the course of the last century, large fractions of the Alpine rivers were dammed to produce hydropower. In recent decades, runoff changes induced by reservoir constructions seem to overlap with changes in snow cover. We suggest that Alpine signals propagate downstream and affect runoff far outside the Alpine area in river segments with mixed flow regimes. Furthermore, our results hint at more (intense) rain-fall in recent decades. Detected increases in high discharge can be traced back to corresponding changes in precipitation.}, language = {en} } @misc{RottlerBronstertBuergeretal.2021, author = {Rottler, Erwin and Bronstert, Axel and B{\"u}rger, Gerd and Rakovec, Oldrich}, title = {Projected changes in Rhine River flood seasonality under global warming}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, issn = {1866-8372}, doi = {10.25932/publishup-52296}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-522962}, pages = {21}, year = {2021}, abstract = {Climatic change alters the frequency and intensity of natural hazards. In order to assess potential future changes in flood seasonality in the Rhine River Basin, we analyse changes in streamflow, snowmelt, precipitation, and evapotranspiration at 1.5, 2.0 and 3.0 ◦C global warming levels. The mesoscale Hydrological Model (mHM) forced with an ensemble of climate projection scenarios (five general circulation models under three representative concentration pathways) is used to simulate the present and future climate conditions of both, pluvial and nival hydrological regimes. Our results indicate that the interplay between changes in snowmelt- and rainfall-driven runoff is crucial to understand changes in streamflow maxima in the Rhine River. Climate projections suggest that future changes in flood characteristics in the entire Rhine River are controlled by both, more intense precipitation events and diminishing snow packs. The nature of this interplay defines the type of change in runoff peaks. On the sub-basin level (the Moselle River), more intense rainfall during winter is mostly counterbalanced by reduced snowmelt contribution to the streamflow. In the High Rhine (gauge at Basel), the strongest increases in streamflow maxima show up during winter, when strong increases in liquid precipitation intensity encounter almost unchanged snowmelt-driven runoff. The analysis of snowmelt events suggests that at no point in time during the snowmelt season, a warming climate results in an increase in the risk of snowmelt-driven flooding. We do not find indications of a transient merging of pluvial and nival floods due to climate warming.}, language = {en} } @misc{SeleemHeistermannBronstert2021, author = {Seleem, Omar and Heistermann, Maik and Bronstert, Axel}, title = {Efficient Hazard Assessment For Pluvial Floods In Urban Environments}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {18}, issn = {1866-8372}, doi = {10.25932/publishup-52215}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-522158}, pages = {19}, year = {2021}, abstract = {The presence of impermeable surfaces in urban areas hinders natural drainage and directs the surface runoff to storm drainage systems with finite capacity, which makes these areas prone to pluvial flooding. The occurrence of pluvial flooding depends on the existence of minimal areas for surface runoff generation and concentration. Detailed hydrologic and hydrodynamic simulations are computationally expensive and require intensive resources. This study compared and evaluated the performance of two simplified methods to identify urban pluvial flood-prone areas, namely the fill-spill-merge (FSM) method and the topographic wetness index (TWI) method and used the TELEMAC-2D hydrodynamic numerical model for benchmarking and validation. The FSM method uses common GIS operations to identify flood-prone depressions from a high-resolution digital elevation model (DEM). The TWI method employs the maximum likelihood method (MLE) to probabilistically calibrate a TWI threshold (τ) based on the inundation maps from a 2D hydrodynamic model for a given spatial window (W) within the urban area. We found that the FSM method clearly outperforms the TWI method both conceptually and effectively in terms of model performance.}, language = {en} }