Assessment of Climate Change Impacts on Floods and Low Flows of the Brahmaputra River

Abstract

The Ganges-Brahmaputra-Meghna (GBM) river system plays a key role in the survival and development of more than 670 million people in South Asia. The extreme flows of the GBM rivers also dictate the occurrences of floods and hydrological droughts in Bangladesh, which lies at the delta of this river system. This study was undertaken to assess the impacts of high-end climate change on the extreme flows as well as the mean monthly flows of these rivers at their downstream locations inside Bangladesh. SWAT Hydrological modeling tools were used to simulate future flows using climate projections collected from the CORDEX initiative. The mean monthly flows are likely to increase in most months of the future in the GBM rivers, and the increases are likely to be largest in the Ganges River compared to the other two rivers in terms of percentage changes. Flood flows and low flows are projected to increase in all three rivers. The frequency of occurrence of flood flows is likely to increase and that of low flows are likely to decrease, especially near the end of this century. The projections presented in this article can be useful in adaptation planning as well as in supporting discussions on mitigation policies.