Hydrological response to climate and land use and land cover change in the Teesta River basin

The Teesta basin is shared by Bangladesh and India, holds significant importance in the bilateral relationship, and sustains the livelihoods of over 30 million people in Bangladesh. Employing a cellular automata (CA) model, we accurately estimate land use and land cover (LULC) for the 2020s and project it for the 2050s and 2080s. A semi-distributed hydrological model, Soil and Water Assessment Tool (SWAT), is used to generate flow for the base period (1995-2014), the near future (2035-2064), and the far future (2071-2100). The SWAT model is forced by eight general circulation models (GCMs) under two socioeconomic pathways (SSP245 and SSP585). The CA-Markov prediction indicates LULC changes, especially an increase in agriculture and settlements by 76 and 42%, respectively, and a decrease in forest and water by 13 and 36%, which are expected by the 2050s and will influence discharge patterns. This results in additional discharge increases of 4% (-8 to 5%) for SSP245 and 5% (-8 to 10%) for SSP585 scenarios during wet seasons. In the far future, monsoon flow will increase by 13% (0.4 to 23%) for SSP245 and 52% (-29 to 151%) under SSP585 scenarios. A marginal change in winter flow was shown by a -6% (-16 to 4%) reduction under SSP245 and a -13% (-64 to 63%) reduction under SSP585 in the 2080s.