Impact of Climate Change on Flood Frequency of the Trian Reservoir in Vietnam Using RCMS

Abstract

Vietnam is one of the countries severely impacted by climate change. The Saigon-Dongnai River basin is one of the largest river basins and the economic center in the south of Vietnam. Trian watershed is located in the upper Saigon-Dongnai River basin and is one of the largest subbasins of this river. However, no study has been conducted to assess the impact of climate change on this region. It is, hence, necessary to evaluate the potential future impact of climate change on this watershed, particularly on flood frequency, because flood events negatively impact economic and social aspects. The downscaled atmospheric data, from the simulations of five Regional Climate Models (RCMs), are used as input data for a physically-based hydrological model to simulate future streamflow data. The changes in the frequency of flood peak extracted by the peak over threshold (POT) approach is compared between historical and future time periods. The results indicate that there is a significant increase in flood magnitude under climate change for the Trian catchment. Specifically, the 1-year return level of Trian reservoir is increasing up to 32.34% in one of the future scenarios. Moreover, results of this study also indicate that directly using the asymptotic distribution to model the POT data set sometimes provides wrong insights.