TY - JOUR A1 - He, Zhihua A1 - Vorogushyn, Sergiy A1 - Unger-Shayesteh, Katy A1 - Gafurov, Abror A1 - Kalashnikova, Olga A1 - Omorova, Elvira A1 - Merz, Bruno T1 - The Value of Hydrograph Partitioning Curves for Calibrating Hydrological Models in Glacierized Basins JF - Water resources research N2 - This study refines the method for calibrating a glacio-hydrological model based on Hydrograph Partitioning Curves (HPCs), and evaluates its value in comparison to multidata set optimization approaches which use glacier mass balance, satellite snow cover images, and discharge. The HPCs are extracted from the observed flow hydrograph using catchment precipitation and temperature gradients. They indicate the periods when the various runoff processes, such as glacier melt or snow melt, dominate the basin hydrograph. The annual cumulative curve of the difference between average daily temperature and melt threshold temperature over the basin, as well as the annual cumulative curve of average daily snowfall on the glacierized areas are used to identify the starting and end dates of snow and glacier ablation periods. Model parameters characterizing different runoff processes are calibrated on different HPCs in a stepwise and iterative way. Results show that the HPC-based method (1) delivers model-internal consistency comparably to the tri-data set calibration method; (2) improves the stability of calibrated parameter values across various calibration periods; and (3) estimates the contributions of runoff components similarly to the tri-data set calibration method. Our findings indicate the potential of the HPC-based approach as an alternative for hydrological model calibration in glacierized basins where other calibration data sets than discharge are often not available or very costly to obtain. KW - hydrograph partitioning curves KW - model calibration KW - glacierized basins Y1 - 2018 U6 - https://doi.org/10.1002/2017WR021966 SN - 0043-1397 SN - 1944-7973 VL - 54 IS - 3 SP - 2336 EP - 2361 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Merz, Bruno A1 - Nguyen, Viet Dung A1 - Apel, Heiko A1 - Gerlitz, Lars A1 - Schröter, Kai A1 - Steirou, Eva Styliani A1 - Vorogushyn, Sergiy T1 - Spatial coherence of flood-rich and flood-poor periods across Germany JF - Journal of hydrology N2 - Despite its societal relevance, the question whether fluctuations in flood occurrence or magnitude are coherent in space has hardly been addressed in quantitative terms. We investigate this question for Germany by analysing fluctuations in annual maximum series (AMS) values at 68 discharge gauges for the common time period 1932-2005. We find remarkable spatial coherence across Germany given its different flood regimes. For example, there is a tendency that flood-rich/-poor years in sub-catchments of the Rhine basin, which are dominated by winter floods, coincide with flood-rich/-poor years in the southern sub-catchments of the Danube basin, which have their dominant flood season in summer. Our findings indicate that coherence is caused rather by persistence in catchment wetness than by persistent periods of higher/lower event precipitation. Further, we propose to differentiate between event-type and non-event-type coherence. There are quite a number of hydrological years with considerable nonevent-type coherence, i.e. AMS values of the 68 gauges are spread out through the year but in the same magnitude range. Years with extreme flooding tend to be of event-type and non-coherent, i.e. there is at least one precipitation event that affects many catchments to various degree. Although spatial coherence is a remarkable phenomenon, and large-scale flooding across Germany can lead to severe situations, extreme magnitudes across the whole country within one event or within one year were not observed in the investigated period. (C) 2018 Elsevier B.V. All rights reserved. KW - Flood timing KW - Spatial coherence KW - Flood regimes KW - Climate variability KW - Catchment wetness Y1 - 2018 U6 - https://doi.org/10.1016/j.jhydrol.2018.02.082 SN - 0022-1694 SN - 1879-2707 VL - 559 SP - 813 EP - 826 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Metin, Ayse Duha A1 - Nguyen Viet Dung, A1 - Schröter, Kai A1 - Guse, Björn A1 - Apel, Heiko A1 - Kreibich, Heidi A1 - Vorogushyn, Sergiy A1 - Merz, Bruno T1 - How do changes along the risk chain affect flood risk? JF - Natural hazards and earth system sciences N2 - Flood risk is impacted by a range of physical and socio-economic processes. Hence, the quantification of flood risk ideally considers the complete flood risk chain, from atmospheric processes through catchment and river system processes to damage mechanisms in the affected areas. Although it is generally accepted that a multitude of changes along the risk chain can occur and impact flood risk, there is a lack of knowledge of how and to what extent changes in influencing factors propagate through the chain and finally affect flood risk. To fill this gap, we present a comprehensive sensitivity analysis which considers changes in all risk components, i.e. changes in climate, catchment, river system, land use, assets, and vulnerability. The application of this framework to the mesoscale Mulde catchment in Germany shows that flood risk can vary dramatically as a consequence of plausible change scenarios. It further reveals that components that have not received much attention, such as changes in dike systems or in vulnerability, may outweigh changes in often investigated components, such as climate. Although the specific results are conditional on the case study area and the selected assumptions, they emphasize the need for a broader consideration of potential drivers of change in a comprehensive way. Hence, our approach contributes to a better understanding of how the different risk components influence the overall flood risk. Y1 - 2018 U6 - https://doi.org/10.5194/nhess-18-3089-2018 SN - 1561-8633 SN - 1684-9981 VL - 18 IS - 11 SP - 3089 EP - 3108 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Di Baldassarre, Giuliano A1 - Kreibich, Heidi A1 - Vorogushyn, Sergiy A1 - Aerts, Jeroen A1 - Arnbjerg-Nielsen, Karsten A1 - Barendrecht, Marlies A1 - Bates, Paul A1 - Borga, Marco A1 - Botzen, Wouter A1 - Bubeck, Philip A1 - De Marchi, Bruna A1 - Llasat, Carmen Maria A1 - Mazzoleni, Maurizio A1 - Molinari, Daniela A1 - Mondino, Elena A1 - Mard, Johanna A1 - Petrucci, Olga A1 - Scolobig, Anna A1 - Viglione, Alberto A1 - Ward, Philip J. T1 - Hess Opinions: An interdisciplinary research agenda to explore the unintended consequences of structural flood protection JF - Hydrology and earth system sciences : HESS N2 - One common approach to cope with floods is the implementation of structural flood protection measures, such as levees or flood-control reservoirs, which substantially reduce the probability of flooding at the time of implementation. Numerous scholars have problematized this approach. They have shown that increasing the levels of flood protection can attract more settlements and high-value assets in the areas protected by the new measures. Other studies have explored how structural measures can generate a sense of complacency, which can act to reduce preparedness. These paradoxical risk changes have been described as "levee effect", "safe development paradox" or "safety dilemma". In this commentary, we briefly review this phenomenon by critically analysing the intended benefits and unintended effects of structural flood protection, and then we propose an interdisciplinary research agenda to uncover these paradoxical dynamics of risk. Y1 - 2018 U6 - https://doi.org/10.5194/hess-22-5629-2018 SN - 1027-5606 SN - 1607-7938 VL - 22 IS - 11 SP - 5629 EP - 5637 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Merz, Bruno A1 - Apel, Heiko A1 - Dung Nguyen, Viet-Dung A1 - Falter, Daniela A1 - Guse, Björn A1 - Hundecha, Yeshewatesfa A1 - Kreibich, Heidi A1 - Schröter, Kai A1 - Vorogushyn, Sergiy T1 - From precipitation to damage BT - a coupled model chain for spatially coherent, large-scale flood risk assessment JF - Global flood hazard : applications in modeling, mapping and forecasting N2 - Flood risk assessments for large river basins often involve piecing together smaller-scale assessments leading to erroneous risk statements. We describe a coupled model chain for quantifying flood risk at the scale of 100,000 km(2). It consists of a catchment model, a 1D-2D river network model, and a loss model. We introduce the model chain and present two applications. The first application for the Elbe River basin with an area of 66,000 km(2) demonstrates that it is feasible to simulate the complete risk chain for large river basins in a continuous simulation mode with high temporal and spatial resolution. In the second application, RFM is coupled to a multisite weather generator and applied to the Mulde catchment with an area of 6,000 km(2). This approach is able to provide a very long time series of spatially heterogeneous patterns of precipitation, discharge, inundation, and damage. These patterns respect the spatial correlation of the different processes and are suitable to derive large-scale risk estimates. We discuss how the RFM approach can be transferred to the continental scale. Y1 - 2018 SN - 978-1-119-21788-6 SN - 978-1-119-21786-2 U6 - https://doi.org/10.1002/9781119217886.ch10 SN - 0065-8448 VL - 233 SP - 169 EP - 183 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Murawski, Aline A1 - Vorogushyn, Sergiy A1 - Bürger, Gerd A1 - Gerlitz, Lars A1 - Merz, Bruno T1 - Do changing weather types explain observed climatic trends in the rhine basin? BT - an analysis of within- and between-type changes JF - Journal of geophysical of geophysical research-atmosheres N2 - For attributing hydrological changes to anthropogenic climate change, catchment models are driven by climate model output. A widespread approach to bridge the spatial gap between global climate and hydrological catchment models is to use a weather generator conditioned on weather patterns (WPs). This approach assumes that changes in local climate are characterized by between-type changes of patterns. In this study we test this assumption by analyzing a previously developed WP classification for the Rhine basin, which is based on dynamic and thermodynamic variables. We quantify changes in pattern characteristics and associated climatic properties. The amount of between- and within-type changes is investigated by comparing observed trends to trends resulting solely from WP occurrence. To overcome uncertainties in trend detection resulting from the selected time period, all possible periods in 1901-2010 with a minimum length of 31 years are analyzed. Increasing frequency is found for some patterns associated with high precipitation, although the trend sign highly depends on the considered period. Trends and interannual variations of WP frequencies are related to the long-term variability of large-scale circulation modes. Long-term WP internal warming is evident for summer patterns and enhanced warming for spring/autumn patterns since the 1970s. Observed trends in temperature and partly in precipitation are mainly associated with frequency changes of specific WPs, but some amount of within-type changes remains. The classification can be used for downscaling of past changes considering this limitation, but the inclusion of thermodynamic variables into the classification impedes the downscaling of future climate projections. KW - attribution KW - weather pattern KW - trend analysis KW - downscaling KW - hypothetical trend Y1 - 2018 U6 - https://doi.org/10.1002/2017JD026654 SN - 2169-897X SN - 2169-8996 VL - 123 IS - 3 SP - 1562 EP - 1584 PB - American Geophysical Union CY - Washington ER -