Surface Water Expansion in the Huayang River Basin Following the Comprehensive Implementation of the River and Lake Chief System

Over the past three decades, China's rapid economic growth has significantly improved living standards but has also led to environmental challenges. The Chinese government launched the River Chief System and the Lake Chief System to promote the sustainable development. We selected the Huayang River basin to assess the impacts of the RLCS after the RLCS implementation. We analyzed Sentinel-1 GRD over 2015–2021 to extract annual water body information, and found: (1) The total surface water area in the Huayang River Basin expanded from 1005.66 km2 to 1241.09 km2. (2) Lake water surface areas expanded by 13.11 km2, river surface areas grew by 3.77 km2, and small and micro water bodies increased by 218.61 km2. (3) Notable increases in specific lakes were observed, with Longgan Lake growing by 4.09 km2, Po Lake by 2.20 km2, Huang Lake by 2.72 km2, Daguan Lake by 0.76 km2, and Dayuan Lake by 1.53 km2. (4) The shift to production-oriented fishing has restored aquatic ecosystems, transitioning aquaculture to coastal lowlands and converting farmland into shrimp-rice paddies and fish ponds. This study offers the first quantitative assessment of RLCS outcomes, providing policymakers in rapidly developing regions with insights and evidence-based strategies for sustainable water governance, applicable globally.