Reservoir dominated spatio-temporal changes of the surface water area in the Yangtze River Basin during past three decades

Yangtze River Basin, China. The surface water area (SWA) of the Yangtze River Basin (YRB) has changed significantly due to intensified human interferences. But no study investigated the variations in different water types and its drivers yet. To figure out the long-term changes in water bodies and the underlying driving forces, an improved method based on satellite data was developed to accurately delineate the seasonal SWA of the YRB from 1990 to 2020. Changes in different categories (reservoirs, lakes, and rivers) of water bodies are discriminated and attributed to various climatic and anthropogenic factors. Trend of the total SWA in the YRB was non-significant, but obvious changes happened at sub-basin scale. The SWA in the source region and upper reaches demonstrated an upward trend, while a decline was observed in the middle and lower reaches. The increase is largely attributed to reservoir changes (70 %). While, the decreases are attributed to changes in lakes (45 %) and rivers (55 %). Attribution analysis reveals that climatic factors primarily drive the SWA changes in the source region (74 %), while human activities play a more substantial role in the upper reaches (64 %). For the middle and lower reaches, climate and human activities have equally influences. This study shed light on the significant impact of human activities on the redistribution of SWA. • Seasonal water maps in the Yangtze River Basin in past 30 years were derived. • Trends of water area varied in different regions and water types. • Reservoir contributed 70 % of the increase, and lake and river mainly decrease. • Climate and human activities have contrasting impacts in different sub-basins.