An integrated assessment of surface water dynamics in the Irtysh River Basin during 1990–2019 and exploratory factor analyses

Climate change and urbanization are jointly impacting on the open surface water area of the Irtysh River in the Arctic Circle. This will affect the economic development and ecology of the countries in the Irtysh River basin and the hydrological cycle of the Arctic Circle. However, the long-term changes of open surface water bodies in the Irtysh River Basin have not been well quantified. To address this, 89,000 Landsat 4,5,7 and 8 images from 1990 to 2019 were used to extract the surface water body area of the Irtysh River Basin and integrated the assessment of open surface water area dynamics. The geographical detector model was used to quantify the factors that affect the area of open surface water bodies. The results show that the total open surface water area of the Irtysh River Basin is an increasing trend over the past 30 years, with a total increase of 88,790 km2, of which the permanent water body area decreased by 20,800 km2 and the seasonal water body area increased by 109,590 km2. In addition, the factors that contributed the most to the dynamics of the surface water area in the Irtysh River Basin were evapotranspiration, precipitation and snow water equivalent, whose contribution rates could reach 72%, 66% and 61%, respectively, with important interactions between factors. This suggests that monitoring dynamics in surface water area requires comprehensive consideration of all factors. Results obtained from this study offer the latest information for fully understanding the spatio-temporal variation of surface water body area and its driving factors in this basin, which could be used to effectively manage water resources for possibly reducing international water disputes and protecting the fragile ecology in the Arctic.