TY - JOUR A1 - Barendrecht, Marlies H. A1 - Viglione, Alberto A1 - Kreibich, Heidi A1 - Merz, Bruno A1 - Vorogushyn, Sergiy A1 - Blöschl, G. T1 - The Value of Empirical Data for Estimating the Parameters of a Sociohydrological Flood Risk Model JF - Water resources research N2 - In this paper, empirical data are used to estimate the parameters of a sociohydrological flood risk model. The proposed model, which describes the interactions between floods, settlement density, awareness, preparedness, and flood loss, is based on the literature. Data for the case study of Dresden, Germany, over a period of 200years, are used to estimate the model parameters through Bayesian inference. The credibility bounds of their estimates are small, even though the data are rather uncertain. A sensitivity analysis is performed to examine the value of the different data sources in estimating the model parameters. In general, the estimated parameters are less biased when using data at the end of the modeled period. Data about flood awareness are the most important to correctly estimate the parameters of this model and to correctly model the system dynamics. Using more data for other variables cannot compensate for the absence of awareness data. More generally, the absence of data mostly affects the estimation of the parameters that are directly related to the variable for which data are missing. This paper demonstrates that combining sociohydrological modeling and empirical data gives additional insights into the sociohydrological system, such as quantifying the forgetfulness of the society, which would otherwise not be easily achieved by sociohydrological models without data or by standard statistical analysis of empirical data. Y1 - 2019 U6 - https://doi.org/10.1029/2018WR024128 SN - 0043-1397 SN - 1944-7973 VL - 55 IS - 2 SP - 1312 EP - 1336 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Rözer, Viktor A1 - Kreibich, Heidi A1 - Schröter, Kai A1 - Müller, Meike A1 - Sairam, Nivedita A1 - Doss-Gollin, James A1 - Lall, Upmanu A1 - Merz, Bruno T1 - Probabilistic Models Significantly Reduce Uncertainty in Hurricane Harvey Pluvial Flood Loss Estimates JF - Earths future N2 - Pluvial flood risk is mostly excluded in urban flood risk assessment. However, the risk of pluvial flooding is a growing challenge with a projected increase of extreme rainstorms compounding with an ongoing global urbanization. Considered as a flood type with minimal impacts when rainfall rates exceed the capacity of urban drainage systems, the aftermath of rainfall-triggered flooding during Hurricane Harvey and other events show the urgent need to assess the risk of pluvial flooding. Due to the local extent and small-scale variations, the quantification of pluvial flood risk requires risk assessments on high spatial resolutions. While flood hazard and exposure information is becoming increasingly accurate, the estimation of losses is still a poorly understood component of pluvial flood risk quantification. We use a new probabilistic multivariable modeling approach to estimate pluvial flood losses of individual buildings, explicitly accounting for the associated uncertainties. Except for the water depth as the common most important predictor, we identified the drivers for having loss or not and for the degree of loss to be different. Applying this approach to estimate and validate building structure losses during Hurricane Harvey using a property level data set, we find that the reliability and dispersion of predictive loss distributions vary widely depending on the model and aggregation level of property level loss estimates. Our results show that the use of multivariable zero-inflated beta models reduce the 90% prediction intervalsfor Hurricane Harvey building structure loss estimates on average by 78% (totalling U.S.$3.8 billion) compared to commonly used models. KW - pluvial flooding KW - loss modeling KW - urban flooding KW - probabilistic KW - Hurricane Harvey KW - climate change adaptation Y1 - 2019 U6 - https://doi.org/10.1029/2018EF001074 SN - 2328-4277 VL - 7 IS - 4 SP - 384 EP - 394 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Sairam, Nivedita A1 - Schröter, Kai A1 - Lüdtke, Stefan A1 - Merz, Bruno A1 - Kreibich, Heidi T1 - Quantifying Flood Vulnerability Reduction via Private Precaution JF - Earth future N2 - Private precaution is an important component in contemporary flood risk management and climate adaptation. However, quantitative knowledge about vulnerability reduction via private precautionary measures is scarce and their effects are hardly considered in loss modeling and risk assessments. However, this is a prerequisite to enable temporally dynamic flood damage and risk modeling, and thus the evaluation of risk management and adaptation strategies. To quantify the average reduction in vulnerability of residential buildings via private precaution empirical vulnerability data (n = 948) is used. Households with and without precautionary measures undertaken before the flood event are classified into treatment and nontreatment groups and matched. Postmatching regression is used to quantify the treatment effect. Additionally, we test state-of-the-art flood loss models regarding their capability to capture this difference in vulnerability. The estimated average treatment effect of implementing private precaution is between 11 and 15 thousand EUR per household, confirming the significant effectiveness of private precautionary measures in reducing flood vulnerability. From all tested flood loss models, the expert Bayesian network-based model BN-FLEMOps and the rule-based loss model FLEMOps perform best in capturing the difference in vulnerability due to private precaution. Thus, the use of such loss models is suggested for flood risk assessments to effectively support evaluations and decision making for adaptable flood risk management. KW - flood loss KW - average treatment effect KW - matching methods KW - loss models KW - risk analysis KW - adaptation Y1 - 2019 U6 - https://doi.org/10.1029/2018EF000994 SN - 2328-4277 VL - 7 IS - 3 SP - 235 EP - 249 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Steirou, Eva A1 - Gerlitz, Lars A1 - Apel, Heiko A1 - Sun, Xun A1 - Merz, Bruno T1 - Climate influences on flood probabilities across Europe JF - Hydrology and earth system sciences : HESS N2 - The link between streamflow extremes and climatology has been widely studied in recent decades. However, a study investigating the effect of large-scale circulation variations on the distribution of seasonal discharge extremes at the European level is missing. Here we fit a climate-informed generalized extreme value (GEV) distribution to about 600 streamflow records in Europe for each of the standard seasons, i.e., to winter, spring, summer and autumn maxima, and compare it with the classical GEV distribution with parameters invariant in time. The study adopts a Bayesian framework and covers the period 1950 to 2016. Five indices with proven influence on the European climate are examined independently as covariates, namely the North Atlantic Oscillation (NAO), the east Atlantic pattern (EA), the east Atlantic-western Russian pattern (EA/WR), the Scandinavia pattern (SCA) and the polar-Eurasian pattern (POL). It is found that for a high percentage of stations the climate-informed model is preferred to the classical model. Particularly for NAO during winter, a strong influence on streamflow extremes is detected for large parts of Europe (preferred to the classical GEV distribution for 46% of the stations). Climate-informed fits are characterized by spatial coherence and form patterns that resemble relations between the climate indices and seasonal precipitation, suggesting a prominent role of the considered circulation modes for flood generation. For certain regions, such as northwestern Scandinavia and the British Isles, yearly variations of the mean seasonal climate indices result in considerably different extreme value distributions and thus in highly different flood estimates for individual years that can also persist for longer time periods. Y1 - 2019 U6 - https://doi.org/10.5194/hess-23-1305-2019 SN - 1027-5606 SN - 1607-7938 VL - 23 IS - 3 SP - 1305 EP - 1322 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Wendi, Dadiyorto A1 - Merz, Bruno A1 - Marwan, Norbert T1 - Assessing hydrograph similarity and rare runoff dynamics by cross recurrence plots JF - Water resources research N2 - This paper introduces a novel measure to assess similarity between event hydrographs. It is based on cross recurrence plots (CRP) and recurrence quantification analysis (RQA), which have recently gained attention in a range of disciplines when dealing with complex systems. The method attempts to quantify the event runoff dynamics and is based on the time delay embedded phase space representation of discharge hydrographs. A phase space trajectory is reconstructed from the event hydrograph, and pairs of hydrographs are compared to each other based on the distance of their phase space trajectories. Time delay embedding allows considering the multidimensional relationships between different points in time within the event. Hence, the temporal succession of discharge values is taken into account, such as the impact of the initial conditions on the runoff event. We provide an introduction to cross recurrence plots and discuss their parameterization. An application example based on flood time series demonstrates how the method can be used to measure the similarity or dissimilarity of events, and how it can be used to detect events with rare runoff dynamics. It is argued that this methods provides a more comprehensive approach to quantify hydrograph similarity compared to conventional hydrological signatures. KW - runoff dynamics KW - cross recurrence plot in hydrology KW - rare flood dynamics KW - hydrograph similarity KW - time delay embedding for runoff series Y1 - 2019 U6 - https://doi.org/10.1029/2018WR024111 SN - 0043-1397 SN - 1944-7973 VL - 55 IS - 6 SP - 4704 EP - 4726 PB - American Geophysical Union CY - Washington ER -