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Introduction
Published in Hieu Quang Ngo, Development of an Efficient Modelling Approach to Support Economically and Socially Acceptable Flood Risk Reduction in Coastal Cities: Can Tho City, Mekong Delta, Vietnam, 2022
Assessing flood risk is an essential part of FRM (including managing both hazard and the potential consequences) which is becoming a critical process for adapting to future changes (for example climate change, economic change and population growth). Flood risk assessment is performed to facilitate the implementation of risk-informed measures aimed at minimizing (or mitigating) flood damage (Hall et al., 2003; Meyer et al., 2009, Bureau Reclamation, 2020; Mishra and Sinha, 2020). However, FRM and planning decisions in many parts of the world have historically utilised flood hazard or damage maps associated with one or two pre-determined return period of water levels (e.g. 100year, 200-year). While this may have been sufficient in the past, the need to move from stationary to innovative time-dependent flood hazard and risk modelling approaches that can account for the uncertainty, arising from anthropogenic and climatic induced stressors, are rapidly increasing (Mosavi et al., 2018). Therefore, contemporary FRM is required to embrace much more statistically robust approaches. In this context, a probabilistic approach is a fundamental requirement for quantitative flood risk assessments, which aid urban planners and decision-makers to develop informed risk reduction strategies that minimize the damage caused by floods. This is especially important for coastal cities which are not only facing the impact of upstream flow changes due to human interventions (land-use change, dam construction) but also the effect of climate change on sea level (tide, sea-level rise, storm surges) as well as the effect of land subsidence in deltas.
Flooding
Published in David Butler, Christopher Digman, Christos Makropoulos, John W. Davies, Urban Drainage, 2018
David Butler, Christopher Digman, Christos Makropoulos, John W. Davies
Ryu and Butler (2008) argue that continuous simulation is more appropriate for urban drainage flood risk assessment than considering single storm events. This allows a more complete and accurate evaluation of flood risk (i.e., the area under the curve in Figure 11.5c). However, this thoroughness comes at the expense of computational and physical time. Dawson et al. (2008) have developed an approach based on urban flood risk assessment but with the additional goal of attributing the risk between key stakeholders.
Understanding flood risk in the context of community resilience modeling for the built environment: research needs and trends
Published in Sustainable and Resilient Infrastructure, 2022
Omar M. Nofal, John W. van de Lindt
Flood risk is the expected damages based on hazard intensity and probabilities of occurrence, the value of the exposed assets, and their location within the flood-prone area, and the vulnerability of these assets. Figure 2 provides a schematic representation of the proposed flood risk assessment and the sequence of overlaying each component within an analysis process. The flood risk analysis started with hydrologic analysis of the study area by conducting analyses on the digital elevation map to extract basins characteristics within the study area and extract the needed parameters to be used as an input for the hydrologic analysis method. Then, the precipitation data was used along with the soil, land use, and the digital elevation map to account for the surface water runoff. Then, the resulting discharges in each stream/river was used as the boundary conditions for a hydrodynamic analysis to determine the flood water depth and velocity spatially over the location of interest. The resulting flood hazard map is then overlaid on the community exposure information to predict the flood hazard characteristics at each building. Finally, vulnerability functions in terms of fragility curves are used to predict the state of damage for each building. Therefore, generally, flood risk assessment process depends on three major phases which include flood hazard mapping by applying the principles of hydrologic and hydraulic analysis, flood exposure information through data collection and numerical modeling, and flood vulnerability analysis to include the susceptibility of the community infrastructure. Modeling the potential flood risk for a specific community provides stakeholders with information to evaluate future investment strategies in flood-prone areas at a community scale. This provides planners the ability to allocate community resources to reduce risk and improve resilience as a result of flood protection measures (Büchele et al., 2006). Therefore, flood risk assessment bridges the gap between the increasing attention of analysts and policymakers in flood risk management worldwide over the last century.