Impacts of Climate Changes on Peak Flow of Upper Meghna River Basin *Md

Bangladesh has been formed as the greatest deltaic plain at the confluence of the Ganges, Brahmaputra and Meghna (GBM) rivers and is highly vulnerable to climate changes according to IPCC reports (IPCC 2007 and IPCC 2014). To understand the consequences of climate changes, hydrological study of these three river basins is required. HEC-HMS is a hydrologic modeling software which includes many of the well-known and well applicable hydrologic methods to simulate rainfall-runoff processes in river basins. In this study, a semi distributed hydrological model of the Upper Meghna river basin with a drainage area of 70263 km 2 is developed using HEC-HMS. Hec-Geo HMS is used to delineate stream network and 22 sub-basins of Upper Meghna River. The model is calibrated at Bhairab Bazar station for the year of 2005 and validated against for the year of 2006. Effects of climate changes are simulated by running the model using the future precipitation data obtained from Global Climate Models (CSIRO-30 and CCCMA-31). Results from those model data are used to predict flow hydrographs for the years of 2050 and 2080. The results show that expected increase in total volume (wet period) using CCCMA-31 and CSIRO-30 precipitation will be in between 29% to 54% and 50% to 54% for the years of 2050 and 2080 respectively. The model developed in this study can be used as a tool to understand the effects of human interventions and changed climatic conditions in the basin area.