Integrated Assessment of CMIP6 Models and Land Cover Change on Water Resources of the Hunza Basin in the Upper Indus

The combined study of climate change and land cover to assess runoff can contribute to effective water resources management. Many studies focused on the expected effects of climate change (CC) on surface runoff, largely ignoring future land cover change. The primary aim of this paper is to use the Soil and Water Assessment Tool (SWAT) to assess the impacts of expected CC and land cover change (LCC) on surface runoff in the Upper Indus Basin, Pakistan. Future land cover scenarios and climate change projections were forecasted using cellular automata artificial neural networks and four downscaled general circulation models (GCMs), respectively. The calibration phase (2008–2010) and the validation phase (2011–2013) were separated from the historical data. The simulated outcomes showed that the SWAT concept worked effectively. The GCM (MPI-ESM1-2-HR), after statistical downscaling using the CMhyd model, projected changes in precipitation and temperature according to two Shared Socioeconomic Pathways (SSP2 and SSP5). These projections and future conditions for land cover were supplied to the calibrated model to assess the potential consequences of CC and LCC on the Hunza River Basin. The baseline era (1990–2015) and the projected time frame (2016–2100), which encompasses the current century, were analyzed on a seasonal scale. The results indicate increased precipitation and consequent inflows all year round within both SSPs. Specifically, through the 21st century, SSP2 (SSP5) predicted a 13% (27.1%) increase in rainfall, leading to significant changes in streamflow patterns in the Hunza River Basin. These changes include an overall increase in mean annual streamflow (ranging from 14.9–32.5%) and a decrease in average monthly streamflow during June, July, and August. Likely, the expected climate changes can significantly influence the seasonal characteristics of streamflow at the Hunza River Basin. Higher stream flows were found to be projected in the future. The paper analyses the impact of CC and LCC on runoff depth and offers some recommendations for those in charge of water resources to ensure the sustainability of the aquatic ecosystem.