Increasing seasonal variation in the extent of rivers and lakes from 1984 to 2022

Abstract. Knowledge of the spatial and temporal distribution of surface water is important for water resource management, flood risk assessment, monitoring ecosystem health, constraining estimates of biogeochemical cycles and understanding our climate. While global scale spatial-temporal change detection of surface water has significantly improved in recent years with planetary scale remote sensing and computing, it has remained challenging to distinguish the changing characteristics of rivers and lakes. Here we analyze the spatial extent of permanent and seasonal rivers and lakes globally over the past 38-years based on new data of river system extents and surface water trends. Results show that while the total permanent surface area of both rivers and lakes has remained relatively constant, the area with intermittent seasonal coverage has increased by 12 % and 27 % for rivers and lakes, respectively. The increase is statistically significant in over 84 % of global water catchments based on Spearman rank correlations above 0.05 and p values less than 0.05. The results of our analysis are shared as the Surface Area of Rivers and Lakes (SARL) database, which contributes to improved understanding of the hydrological cycle and management of water resources.