Surface Water Area Mapping in Huai River Basin over the past three decades from Landsat imagery based on Google Earth Engine

Accurate mapping of Dynamics of surface water is essential for supporting sustainable water source management and socio-economic development. To obtain a dynamic map of surface water, we obtained all available Landsat TM, ETM+, and OLI images (16760 scenes) of Huai River Basin from 1989 to 2017 based on Google Earth Engine (GEE) platform. The water surface extraction method combining vegetation index and water index was used to map the spatio-temporal pattern of the surface water body. Results show as follows: (1) the maximum, average and seasonal surface water area in the Huai River Basin shows a downward trend in the past three decades, but the minimum surface water area shows a slight upward trend; (2) both the number of maximum and the minimum surface water body show a downward trend in the past three decades; (3) the changes of numbers of surface water bodies are mainly depended on the number of small surface water bodies, and the changes in the area of water bodies are mainly controlled by larger surface water bodies area. The results of the Surface water mapping are expected to provide detailed information for optimizing water structure and water source management which are critical issues in this region.