Flood hazard assessment in Chenab River basin using hydraulic simulation modeling and remote sensing

This paper analyses flood frequency and performs flood simulation modeling along the Chenab River from Trimmu-Panjnad reach, to simulate flood 2014 and identify resultant flood inundated areas, under different return periods of floods. The aim of this study is to assist policymakers in designing efficient flood mitigation policies for the Chenab River, Pakistan which has been frequently hit by floods, especially in September 2014. Flood frequency analysis was carried out using log-Pearson type III (LP3) distributions to estimate peak flows with various return periods. The peak floods were incorporated into the Hydrologic Engineering Centre River Analysis System (HEC-RAS) model to predict the relevant flood levels for river stretches from Trimmu to Panjnad reach. The HEC-RAS model outcomes were integrated with ArcGIS to prepare flood risk maps that helped in identifying different flood-vulnerable areas. Two flood risk zones were developed; low to moderate and high to very high flood risk zones. The simulation analysis of a 50-year flood period showed that about 400% of the land would be submerged when compared to normal river flow. The simulation of the flood 2014 extent was found to clearly match the MODIS images provided by the United Nations Satellite Centre (UNOSAT). The surface areas of floods having different return periods, were also estimated. The utilization of the HEC-RAS model for simulating the 2014 flood, presents an opportunity for flood policymakers to enhance their understanding and formulate effective risk reduction strategies in the Chenab River basin.