Long-term spatiotemporal changes of surface water and its influencing factors in the mainstream of Han River, China

Study region: Han River mainstream, China. Study focus: Human activities and climate change are synergistically impacting on the spatiotemporal features of Han River surface water, which affects the ecological environment evolution and economic development of the basin. However, the long-term changes of the area and spatial characteristics of Han River surface water have not been well quantified for lack of sufficient data and data processing powers. The study produced the annual surface water products of Han River mainstream from 1986 to 2020 based on Google Earth Engine and Landsat images, and then analyzed the long-term spatiotemporal dynamics of surface water and the influence of climatic factor and water conservancy projects construction. New hydrological insights for the region: During the past 35 years, the surface water area of Han River mainstream has shown a fluctuating upward trend overall, and the dynamic changes have obvious regional and phased differences. Precipitation is the main climatic factor affecting the surface water area changes. With precipitation changes and the implementation of water conservancy projects in Han River, the surface water area has increased significantly and many reaches have gradually widened in upstream, while the surface water area has slowly decreased and many reaches have gradually narrowed in mid-downstream. The latest information about the spatiotemporal dynamics of Han River surface water provided by the research can be used for the optimal allocation and management of the river’s water resources.