Methodology to Assess Potential Flood Damages in Urban Areas under the Influence of Climate Change

Abstract

Frequencies of extreme precipitation are likely to increase under changing climate, which may result in more damage to exposed properties in the future. This study presents a methodological framework for estimating potential economic damages to flood hazards based on current and future climatic information using loss functions. Loss functions for Sri Lanka’s residential structure categories were derived from empirical data through a questionnaire survey in Kelani River basin, Sri Lanka. Flood prediction was done using a bias-corrected 5-year time series of the Japanese Meteorological Research Institute (MRI)’s Regional Climate Model (RCM) precipitation data for current (1985–1989) and near future climate (228–232), and a hypothetical future climate projection using a 1% increase in current high rainfall events. The authors simulated extreme river discharges and inundation depths for potential current and future flood events using similar hydrologic element response (SHER) and geographic information system (GIS) grid-based models, respectively. Simulated extreme flood hazards were integrated with the established loss functions and exposures to simulate the potential damages using a raster-based spatial model. Results revealed a little reduction in the MRI projected near future discharges and flood damages, but an increase in the frequency of flood events compared to the current projection. However, the hypothetical projection showed a 1.2% increase in potential damages in the future climate compared with the current climate. Future adaptation measures in the river basin are suggested.