Journal of Flood Risk Management最新文献

The July 2021 flood heavily affected many inhabitants, buildings and critical infrastructure throughout Germany, Belgium and the Netherlands. Specifically, the Ahr Valley (Germany) showcased the destructive power associated with these extreme events. Hence, this region was the focus of a field survey, aiming at describing the flood-induced damage to buildings and assessing the possible underlying processes that led to structural failures. The field assessment revealed a close connection between building failures and (1) local flow depths and velocities, (2) building location, (3) distance from the riverbank and (4) construction type. Although it is difficult to identify the exact causes that induced failures, the detailed assessment revealed that damages mainly originated from local scour and hydraulic loads, often unevenly distributed around buildings. Importantly, many buildings were significantly affected by (large) floating debris impacts and damming, both responsible for additional loads, highlighting their importance in flood-resistant building design. Furthermore, data showed that buildings near the riverbanks and in the upstream part of villages were more severely damaged. Altogether, data provide a better understanding of the flood processes that lead to building failures, fostering future research towards the development of safer protection measures and more effective flood risk management strategies.

Nature-based coastal adaptation is a subset of nature-based solutions that has to this point focused on the materiality of managing coastal risks: what our coastal protections are made of or where we put things that are in the way of harm. In our collaborative interdisciplinary work, we have been reimagining nature-based coastal adaptation to start with first principles: how we think about the coast and what makes a good coastal life. In a nature-based approach our shared sense of what is good and possible, also known as the social imaginary, needs shifting before any physical material. This paper presents a new nested framework for thinking about nature-based coastal adaptation using five words starting with R: Reimagine, Reserve, Relocate, Restore, Reinforce. We use the nature-based adaptation option of managed dyke realignment in Bay of Fundy agricultural dykelands to illustrate the utility of the framework in practice but assert its more generic applicability.

Mountain torrents are frequent and severe hazards, causing serious economic losses and personnel casualties, and in particular, they are the most dangerous threat in the complex terrain. Multi-source precipitation products should be used to drive the hydrological models to improve understanding of the processes of mountain torrents. Fifteen sets of precipitation products are evaluated against the ground observations in situ within a serious mountain torrent caused by a severe rainstorm at June 26, 2020 in Sichuan. The multi-source merged precipitation products performed better than the others. Satellite-based precipitation performed better than model-based products, while IMERG-Early and FY2G performed better than other satellite-based precipitation products. The reanalysis datasets are relatively worse than the observed products. The operational NWPs strongly underestimated precipitation in the mountainous areas. Furthermore, the related floods caused by the rainstorm is simulated based on various precipitation products by a raster-based hydrodynamic two-dimensional model of FloodArea. Most observation-based precipitation products represented the flooding area well, while the model-based precipitation products underestimated the severity of the mountain torrents. Finally, the risk of mountain torrents under variant return-period rainfall is analyzed. The result shows the potential of real-time torrent monitoring and forecasting using high-resolution DEM and precipitation products.

Land use change, managed retreat, and relocation programs are examples of exposure reduction measures in flood risk management (FRM). Exposure reduction measures are especially prone to conflict at the local level due to competing interests, values, and attachments. In this paper, we build upon the capability approach to justice and specifically the concept of political capabilities to advance justice in exposure reduction measures in FRM. A capabilities-based approach to justice helps to recognize the multiplicity of valuable ways of life and addresses a wide range of inequalities including concerns related to recognition justice. The innovation of our capabilities-based approach to justice is that we include both actors who have too little political influence as well as those who have too much and can thus excessively steer FRM in their advantage. A political capabilities analysis is different than a focus on principles or rights because it draws attention to realized political influence and includes the informal stages of FRM politics such as lobbying. The political capabilities concept also shifts the focus from vulnerability to human agency, thereby addressing concerns in the FRM literature about the loss of self-determination and misrecognition. The paper concludes with a critical discussion of the opportunities and limitations of using the political capabilities concept in FRM.

Hydraulic modelling of culverts relating to the flood risk posed by debris in watercourses has previously only assessed the impact of fixed culvert blockage levels, without analysing the change in flooding as blockage levels increase. With increasing flow rates in rivers during flood events, there is concern that existing culverts may be undersized and therefore already posing a substantial flood risk regardless of them becoming blocked by debris. In this article, two-dimensional (2D) flood modelling is used to produce flood maps detailing the change in flood area and property flooding as culverts become increasingly blocked at several sites in the Northwest of England. The results show a clear distinction between sites where the accumulation of blockage is the key contributing factor towards local flood risk, and sites where the presence of the culvert itself is the predominant flood risk factor. The blockage induced flood risk metric is introduced to characterise the contribution of culvert blockage to the overall flood risk.

Cap-Haïtien, the second largest city in Haiti, is highly vulnerable to earthquakes, landslides, and flooding. The rapid pace of urbanization and deforestation has exacerbated the risk of flooding, resulting in disasters in November 2012, 2016, and 2022. This study aims to assess the impact of urbanization and deforestation on river flooding in Cap-Haïtien by applying the hydrological model Soil Water Assessment Tool (SWAT) and the hydrodynamic model Sobek-Rural. We examined the current situation and a scenario of future urbanization and deforestation. Urbanization and deforestation are found to play a pivotal role in the production and deposition of sediment along the lower Haut-du-Cap River reaches. The existing hydraulic capacity of the river and its drainage system cannot handle the estimated peak flows. The mountain ravines west of the city are found to be the primary source of sediment-laden flash floods. We recommend retention basins, drainage extensions, and pragmatic public policies to mitigate flood risk. Comprehensive strategies are needed to address the detrimental effects of urbanization and deforestation on flooding in Cap-Haïtien and similar regions where a lack of water governance has worsened the flooding alongside urbanization and deforestation. We generalize our experiences from Cap-Haïtien into a broader framework for data-scarce areas.

Although conceptually attractive, the use of ensemble data assimilation methods, such as the ensemble Kalman filter (EnKF), can be constrained by intensive computational requirements. In such cases, the ensemble optimal interpolation scheme (EnOI), which works on a single model run instead of ensemble evolution, may offer a sub-optimal alternative. This study explores different approaches of dynamic covariance matrix generation from predefined state vector repositories for assimilating synthetic water level observations with the EnOI scheme into a distributed rainfall-runoff-inundation model. Repositories are first created by storing open loop state vectors from the simulation of past flood events. The vectors are later sampled during the assimilation step, based on their closeness to the model forecast (calculated using vector norm). Results suggest that the dynamic EnOI scheme is inferior to the EnKF, but can improve upon the deterministic simulation depending on the sampling approach and the repository used. Observations can also be used for sampling to increase the background spread when the system noise is large. A richer repository is required to reduce analysis degradation, but increases the computation cost. This can be resolved by using a sliced repository consisting of only the vectors with norm close to the model forecast.

The frequency analysis method is commonly used to calculate design floods. Under the double challenge of the non-stationary situation under the changing environment and the inadequate length of flood series, developing a new method to integrate the historical extraordinary floods into the non-stationary frequency analysis is essential. First, the Multi-Model Ensemble projections of temperature and precipitation based on Global Climate Model outputs were employed to drive the Soil & Water Assessment Tool hydrological model for runoff simulation. Then, the Integrated Time-Varying Moment (ITVM) model was developed to re-analyze the design floods based on the Pearson-III distribution. The calibrated SWAT model can satisfactorily simulate the rainfall-runoff relationship in the Yalong River basin. The developed ITVM model is effective to conduct the design flood frequency analysis to cope with the problems of insufficient length and non-stationarity of the flood series. The design flood values of Maidilong station show an obvious increase, with variations of 6.5%–9.4%, 2.9%–12.3%, and 16%–33.7% for SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. The significant increase of low frequencies (p = 0.2%, p = 0.1%) floods, especially for SSP5-8.5 scenario, requires more attention, as the increased floods may exceed the discharge capacity of the reservoir determined at the design stage.

The intent of households to relocate amidst floods in Ghana's Greater Accra Metropolitan Area, using combined socio-demographic and physical factors is analyzed within 1206 households. The National Master Sampling Frame of Ghana's Population and Housing Census is utilized for the sampling. The Probit estimation technique is employed to understand the intersectionality of social, economic, demographic, and physical considerations influencing households' decision-making regarding relocation amidst flood risks. The findings show households' reluctance to relocate contrary to relocation considered mostly as preferred adaptation. The likelihood of relocating exhibited a non-linear pattern, decreasing only when a population was younger until age 55 before reversing. Indigenous households preferred not to relocate. In communities where place attachment and revenue sources significantly impacted relocation decisions, households with secondary education, past flood experiences, and non-indigenous status influenced higher perception of flood risk. Therefore, relocation as an effective global adaptation strategy to floods is not widespread. Thus, empowering households to accept a certain level of flood risk potentially avoids maladaptation and involves a combination of hard infrastructure measures and regulatory approaches in places of residence that do not compromise livelihoods. However, if relocation becomes necessary, a right-based approach must be favored over an absolute risk-based approach.