Assessment of climate change impacts for two tributary basins of the Irtysh River in Kazakhstan

Information about the climate change impacts on river discharge of 2 tributary basins of the Irtysh River, the Oba and Ulbi, is important for effective management of the water resources of the Shulba reservoir in Kazakhstan. The main aim of the study was to investigate potential changes in water resource availability in the study basins. To assess the projected changes, the process-based eco-hydrological model SWIM was used under 2 Representative Concentration Pathway (RCP) climate scenarios obtained from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). Our results show an increase in mean annual temperature of 6.1°C, an increase in average annual precipitation of 7.5 to 14%, an increase in annual average discharge for the Oba (6 to 8%) and smaller discharge changes (below 5%) for the Ulbi at the end of the century under RCP8.5—a scenario of comparatively high greenhouse gas emissions—compared to the reference period (1981-2010). Seasonal variations are marked by the peak discharge occurring up to a month earlier, a decrease in the duration of snow accumulation and a reduction in discharge during the summer months. The peak discharge period is prolonged in time, and a slight increase in river discharge could be expected from October to December. Possible future changes in climate may have serious impacts on water resources, agriculture and economic development in the case study basins. The results of this study can be extrapolated to other neighboring basins in Kazakhstan with similar climatic and geophysical characteristics.