Assessment of the tidal effect on flood inundation in a low‐lying river basin under composite future scenarios

Abstract

Abstract Large‐scale flooding causing widespread devastation is expected to increase in the low‐lying river basin of developing countries. Flood inundation occurring in deltaic environments are caused by both river runoff and tides. Furthermore, flood risk in deltas can be exacerbated by composite driving forces, such as future climate change, land‐use change, and sea‐level rise. Flood hazard maps have provided one way to visualize flood risk, and are generally created with future projection. However, existing hazard maps have not incorporated the tidal effect and have not assessed the impact of these three future driving factors simultaneously. Here we presented a method to quantify and visualize the tidal effect on flood inundation under current and future scenarios by coupling rainfall‐runoff and inundation models, and tide level data. We found simulations of the composite future scenario indicate a 1.27‐fold increase in the inundation area, with a two‐fold increase in the extent of the tidal effect for the case of a with any return period rainfall event. These achievements can be used to provide flood hazard maps that also visualize the tidal effect. This new information will enhance our understanding of flood risk in low‐lying areas and contribute further to disaster risk reduction.

Keywords

• coastal
• climate change
• land use
• hydrological modeling