SWOT-derived water surface elevation of reservoirs in China's Yangtze Sub-Basin.

The dataset contains high-fidelity Water Surface Elevation (WSE) time series for 305 reservoirs, covering the period from July 2023 to August 2025. These time series were derived from the SWOT L2_HR_Raster product using a rigorous five-step processing workflow. Initially, data pixels underwent strict quality control (wse_uncert < 0.2 m and wse_qual < 2) to ensure reliability. Valid pixels were then spatially matched with static reservoir boundaries from the CRD to isolate relevant observations. To further refine the data, extreme outliers were removed using the Interquartile Range (IQR) method, followed by aggregating the remaining pixels into a stable median WSE value for each epoch. Finally, the time series were constructed chronologically and smoothed using a Savitzky-Golay filter to effectively reduce noise and residual temporal outliers, resulting in the clean, ready-to-use dataset presented in the file.