CLIMATE CHANGE IMPACT STUDY ON FLOOD RISK IN LOWER WEST RAPTI RIVER BASIN USING MRI-AGCM OUTPUTS

Super high-resolution AGCM precipitation outputs of Meteorological Research Institute, Japan Meteorological Agency (MRI-AGCM 3.1S and 3.2S) for emission scenario A1B were utilized with their bias correction so as to obtain the precipitation patterns over West Rapti River basin for present and future periods. A hydrologic model, PDHM Ver.2 was employed to obtain the time series of daily river discharges for the above mentioned time durations followed by frequency analyses for probable flood discharges of 25- and 50-year return periods. Flood inundation simulations of 50-year return period events for Present and Future were carried out with the Rainfall-Runoff-Inundation model followed by a flood risk assessment based on the simulated flooding depths and durations for household and agriculture over the target area. Future flooding depths in the area show a significant increment compared to the Present situation despite of their relatively big uncertainties. These variations in Future climate will cause complex implications on the adaptation strategy.