Journal of Flood Risk Management最新文献

Jakarta, a bustling Asian city, grapples with flooding issues due to urbanization, land subsidence, and climate changes. To tackle these challenges, an innovative solution is needed. This study assesses paddy field dam (PFD) to address these complex flood issues. PFD is the latest innovation of flood countermeasure from Japan, by applying the water storage concept on a paddy field to hold runoff before it flows into a river. We compared PFD to four other countermeasures such as embankment, river dredging, river widening, and long storage. A combination of rainfall runoff model and flood inundation model were employed to evaluate the impact of these countermeasures. Expected annual damage cost and benefit–cost ratio were used to assess economic feasibility metrics. The combination of land use change, land subsidence, sea level rises, and climate change was adopted to represent a future condition. This study found that the potential of PFD as flood prevention is very good. In the face of impending flood challenges and climate change impacts, the PFD emerges as a promising and economically viable solution, significantly contributing to Jakarta's sustainable flood management journey.

Flood hazards pose a significant threat to communities and ecosystems alike. Triggered by various factors such as heavy rainfall, storm surges, or rapid snowmelt, floods can wreak havoc by inundating low-lying areas and overwhelming infrastructure systems. Understanding the feedback between local geomorphology and sediment transport dynamics in terms of the extent and evolution of flood-related damage is necessary to build a system-level description of flood hazard. In this research, we present a multispectral imagery-based approach to broadly map sediment classes and how their spatial extent and relocation can be monitored. The methodology is developed and tested using data collected in the Ahr Valley in Germany during post-disaster reconnaissance of the July 2021 Western European flooding. Using uncrewed aerial vehicle-borne multispectral imagery calibrated with laboratory-based soil characterization, we illustrate how fine and coarse-grained sediments can be broadly identified and mapped to interpret their transport behavior during flood events and their role regarding flood impacts on infrastructure systems. The methodology is also applied to data from the 2022 flooding of the Yellowstone River, Gardiner, Montana, in the United States to illustrate the transferability of the developed approach across environments. Here, we show how the distribution of soil classes can be mapped remotely and rapidly, and how this facilitates understanding their influence on local flow patterns to induce bridge abutment scour. The limitations and potential expansions to the approach are also discussed.

England experienced a sequence of extreme flood events between June 2019 and April 2021. To understand the severity and likelihood of the events, a set of over 300 flow and river level stations was investigated for key events (identified by Environment Agency Area Teams), focusing on frequency analysis of peak flow, peak level and cumulative flow volume. In addition, groundwater, soil moisture and seasonal total rainfall were analysed to understand the antecedent conditions affecting the impacts of the rainfall experienced. While the period contained some of the wettest months on record, there were few extreme short-duration rainfall events. Record-breaking flows and river levels were seen across the country, in part due to the extreme antecedent conditions where many parts of England had record groundwater levels and soil moisture content preceding the events. A kernel density approach was used to identify statistically significant clusters of events over the study period (compared with a Poisson process) and found that most stations in northern and western England experienced a cluster during the study period. Urbanisation was investigated as a possible driver of these trends, but urban increase was not seen to be a significant driver.

On August 9–10, 2021, the Koakagawa Bridge in Mutsu, Aomori Prefecture, Japan, collapsed owing to the flood caused by a tropical cyclone. In this study, the cause of the collapse was examined. The characteristics of flood inundation with bypassing flows and countermeasures for bank erosion due to channel blockage by driftwood were investigated based on field surveys and numerical simulations. The scouring of the bed around the bridge pier was found to be the cause leading to bridge failure. Channel blockage owing to driftwood would have caused flood inundation and damage to the left bank, the top of the bank is bare of sediment, by forming a bypassing flow. However, the surface of the right bank on which the bypassing flow with high velocity formed was covered with concrete; therefore, bank erosion did not occur. These results indicate that to prevent bank erosion caused by bypassing flows during floods, it is important to protect banks downstream of the bridge using non-erosive materials. Only a small area, where bypassing flows form and non-dimensional shear stress is larger than 0.05, is sufficient for protection. It is also important to predict bed degradation characteristics around piers and banks, especially when the bed material is small.

In synergy with hydraulic works, hydro-meteorological forecasts and related preventive protection measures are effective tools for mitigating flood risk. Nevertheless, the performance and reliability of coupled prediction systems in real-time operations are often influenced by errors in meteorological and hydrological models and their interactions. The paper discusses the source and magnitude of such combined errors, analyzing the functionality of a warning system to predict river floods in northern Italian catchments. The proposed flood alert tool consists of a hydrological model, driven by atmospheric forcings from various weather models and ground observations. This study aims to analyze the sources of flood forecasting errors in small urbanized river basins by disentangling the uncertainties in precipitation and discharge predictions. The results emphasize the relationship between quantitative precipitation and peak discharge forecast errors during convective and stratiform events, with a prevalent tendency toward underestimation of peak flows. The paper highlights the added value and limitations of the real-time multi-model approach as an effective compromise amidst the wide spread of model forecasts. This assessment is based on 4 years of operational simulations (2019–2022) on the river Seveso, where a municipal monitoring system for flood alerts (MOCAP) has also been implemented to support local civil protection procedures.

In July 2021, a flash flood event affected hilly watersheds in Western Germany and neighbouring countries. Many people reported being surprised by the event and in Germany, there were 190 fatalities recorded, pointing to failures in the flood early warning system. We analyze the warning situation based on the results of an online survey with 1351 participants from the most affected areas in two German federal states, Rhineland-Palatinate (RLP), and North Rhine-Westphalia (NRW). Among other topics, the survey addressed whether and when residents received a flood warning and if they knew what to do in response to a flood. We look at differences in the performance of the warning system at the district level and at the watershed segment level from upstream to downstream. We find significant differences between the districts but also due to the location of districts within different federal states and the presence of operational flood forecasting systems. We find some differences between watershed segments; however, the severity of the flood is more important than location within the watershed. Results show that timely warnings through official channels based on operational flood forecasting can help close the warning gap for flash floods.

The aim of this study is to determine the level and source of pollution by potentially toxic elements (PTEs) due to torrential floods in the catchment area of the Drina River under complex geological conditions. The degree of soil and sediment pollution by PTEs was estimated by calculating the Pollution Index (PI) and the Geo-accumulation index (Igeo). Sources of PTEs were determined using Principal component analysis (PCA) for soil and sediment and the Positive Matrix Factorisation (PMF) model for sediment. To fully include the spatial component when determining the source of PTEs, Bivariate Local Moran's I analysis was also applied. By comparing the applied methods, it was determined that PCA is suitable for determining the sources of PTEs in soil and for investigating the sedimentation process in sediment, while the PMF model is more suitable for determining the sources of PTEs in sediment. It was also determined that when the geological substrate is rich and after high-intensity flooding, there is an increase in As, Cd, Co, Cu and Fe content in sediment compared with soil. Arsenic was partially impacted by anthropogenic factors, with Igeo values for soil (16.21%) and sediment (21.76%) at the polluted level.

Mooyaart, L. F., Bakker, A. M. R., Bogaard, J. A., Jorissen, R. E., Rijcken, T., & Jonkman, S. N. (2025). Storm Surge Barrier Performance—The Effect of Barrier Failures on Extreme Water Level Frequencies. Journal of Flood Risk Management, 18(1), e13048. https://doi.org/10.1111/jfr3.13048

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Flash floods and coastal flooding are more and more frequent and damaging in the context of climate change. In addition, the concentration of the population in urban areas contributes to increasing flood risk in these areas. Furthermore, not all territories are at the same level in their risk and resilience management approaches. Regarding this, the French overseas territories have been identified as particularly vulnerable to flood risk. This is the case for Tahiti, the main island of French Polynesia where the capital is located. It is a dense urban area subject to coastal and river flooding hazards, largely exacerbated by the physical environment. Our goal is to propose a method to assess flood resilience in Tahiti. We developed an indicator-based method and used GIS to produce and represent a spatial analysis of territorial resilience. We developed a list of comprehensive spatial indicators that take into account three main dimensions: a structural dimension (e.g., building resilience), an organisational dimension (e.g., the resilience of actions during crisis) and a socio-economic dimension (e.g., human economic capital). The final objective of this research is to design decision-making tools for territorial stakeholders to help them in long-term reflection and collaboration.

Climate change and Land Use Land Cover Change (LULCC) impact on rainfall and runoff is globally evident. However, flash flood impacts on drylands are rarely investigated. A comparable watershed in the dryland of Sudan experienced devastating flash flood impacts for the last four decades (1980s–2020s). The unexpected severity of the 2013 flash flood prompted an investigation into hydrologic and LULCC to determine its cause. We combined spatial cloud computing with hydrological analysis to investigate the relationship between LULCC and peri-hydrological processes for four decades. The Landsat time series analysis shows significant LULC changes: agricultural and rangelands decreased by over 80%, while urban and barren areas increased by 81% and 31%, respectively. The daily rainfall analysis shows that rainstorms exceeding 40 mm were classified as destructive only under wet antecedent soil moisture conditions (1988, 2009, and 2019). Unexpectedly, the 41 mm rainstorm in 2013 occurred under dry conditions. The respective flood magnitude was 4.6 Mm3 according to the US-Natural Resources Conservation Service (US-NRCS). This represents only 14% of the potential runoff under wet conditions (32.3 Mm3) for the same rainstorm. Therefore, the devastating impact of the rainstorm emphasizes the impact of LULCC on flood dynamics in peri-urban areas of drylands.