Floods and climate change: interactions and impacts.

Flood risk analysis for metropolitan areas – a case study for Shanghai

This study aims to target the threat and risk of flooding in Sirimau District, Ambon City from a multi-criteria perspective using a Geographic Information System (GIS). Important flood hazard characteristics include land use, elevation, slope, distance from rivers, soil, and rainfall. Two risk factors, namely population density and land use as well as flood hazard characteristics are used in flood risk analysis. Map aggregation procedure for flood risk and hazard analysis uses the Weighted Linear Combination (WLC) approach. The results of the flood hazard at the study site revealed that the flood hazard category was very high and high, namely 12.26%, and the flood hazard category was very low and low, namely 87.84% and only. The results of the flood risk in the research location revealed that the flood risk with very high and high-risk categories was around 17.28%, and very low and flood low-risk categories (82.77%). This is because the Sirimau District is mostly dominated by hilly and mountainous areas.

Managing flood risks in a changing climate

Whether the high number of river flood disasters in recent years in different European countries and many other areas of the globe are triggered or worsened by human activities has been the subject of a great deal of debate. Possible anthropogenic activities leading to increased flood risk include river regulation measures, intensified land use and forestry, and emissions of greenhouse gases causing a change in the global climate. This article discusses the latter by presenting modelling studies of three meso-scale catchments in Germany. These catchments represent different conditions of land-use, landscape morphology and climate type, therefore showing different dominating flood generation processes. The results of the case studies show how changes of temperature and rainfall regime can lead to significant changes in flood risk. A development towards both an increase or a decrease of the frequency and/or magnitude of flood events is possible, depending mainly on the altered timing of snow accumulation and snowmelt and of a possible shift in rainfall seasonality and intensity.

Integrated real-time flood risk identification, analysis, and diagnosis model framework for a multireservoir system considering temporally and spatially dependent forecast uncertainties

Despite traditional measures to prevent disasters, climate change and urbanization increase flood risk. Thus, flood resilience has attracted increased global concern. Understanding the commonalities and differences between flood resilience and risk is arguably important for flood risk reduction. However, these factors have been seldom reported in previous studies, and discussions on the role of flood resilience in flood risk analysis, assessment, and management are lacking. In this study, the association between flood resilience and risk is discussed using a case study in the Pearl River Delta. Flood resilience is quantified using a pressure-state-response (PSR) model, while flood risk is assessed based on the hazard-vulnerability framework and the extension catastrophe progression method. The implications of considering flood resilience in flood risk analysis, assessment, and management are proposed. The results suggest that the overall flood resilience (risk) in the study area is greater (lower) than that in the highly urbanized areas, and areas with low (high) flood resilience (risk) are mainly concentrated within the highly urbanized areas. Indices extracted from human society and highly related to human activities have the same attributes in both frameworks, while indices associated with climate and geography contribute to the two con- cepts differently. Flood resilience supplements the concept of flood risk, and can be incorporated into risk assessment as an index. Moreover, pre-disruption (post-disaster) measures should follow flood risk (resilience) assessment, and strategies that foster flood resilience should be included in flood risk management. This study provides references for flood resilience improvement and risk mitigation.

Towards flood risk reduction: Commonalities and differences between urban flood resilience and risk based on a case study in the Pearl River Delta

This study targets the threat and risk of flooding in Sirimau District, Ambon City, from a multi-criteria perspective using a Geographic Information System (GIS). Important flood hazard characteristics include land use, elevation, slope, distance from rivers, soil, and rainfall. Two risk factors, namely population density, land use, and flood hazard characteristics are used in flood risk analysis. Map aggregation procedure for flood risk and hazard analysis uses the Weighted Linear Combination (WLC) approach. The results of the flood hazard at the study site revealed that the flood hazard category was very high and high. Namely, 12.26% and the flood hazard category was very low and low, 87.84% and only. The results of the flood risk in the research location revealed that the flood risk with very high and high-risk categories was around 17.28%, and deficient and low flood risk categories (82.77%). This is because hilly and mountainous areas mostly dominate the Sirimau sub-district

Confronting complexity

Editorial: steps towards global flood risk modelling

To mitigate climate change at local, regional, and global scales, we must begin to think beyond greenhouse gases.

The impact of land use- and climate change on the managed eco-geomorphic balance in the Alps

Flood can be assessed through flood vulnerability, risk, and susceptibility analysis using remote sensing, geographic information system, and hydrological modelling. In this chapter, different stages, complexities, and processes of flood vulnerability, risk, and susceptibility assessment were discussed. The study reveals that flood vulnerability should be assessed based on four aspects: physical, social, economic, and environmental. Flood risk should be assessed by three stages: risk analysis, disaster relief, and preparedness, whereas flood susceptibility assessment involves three processes. Overall, it was found that the responsible factors vary as per the local conditions, which need to be carefully analyzed and selected. Furthermore, the role of remote sensing and geographic information system in flood risk management were found important especially in flood risk mapping and in the selection of responsible flooding factors.

Vietnam has a long history and experience with floods. Flood risk is expected to increase further due to climatic, land use and other global changes. Can Tho City, the cultural and economic center of the Mekong delta in Vietnam, is at high risk of flooding. To improve flood risk analyses for Vietnam, this study presents novel multi-variable flood loss models for residential buildings and contents and demonstrates their application in a flood risk assessment for the inner city of Can Tho. Cross-validation reveals that decision tree based loss models using the three input variables water depth, flood duration and floor space of building are more appropriate for estimating building and contents loss in comparison with depth–damage functions. The flood risk assessment reveals a median expected annual flood damage to private households of US$3340 thousand for the inner city of Can Tho. This is approximately 2.5% of the total annual income of households in the study area. For damage reduction improved flood risk management is required for the Mekong Delta, based on reliable damage and risk analyses.

Resilience