Global mapping of small agricultural reservoirs reveals a hidden water storage network

Small agricultural reservoirs form critical, decentralized water-storage networks that support irrigation, livestock, and food production, particularly in regions lacking large-scale water infrastructure. Despite their functional importance, these dynamic water bodies have historically been underrepresented in global surface-water inventories. This dataset provides the first spatially explicit, seasonally resolved global inventory of small agricultural reservoirs. Covering the hydrological year from March 2024 to February 2025 , the dataset maps water bodies ranging from 300 to 100,000 m² at a 10 m spatial resolution. Derived from a fusion of Sentinel-1 radar and Sentinel-2 optical imagery, the dataset identifies approximately 5.1 million reservoirs globally, adding 11.3% (34,500 km²) to current estimates of artificial terrestrial water surface area. The data is segmented into four meteorological seasons to capture the high temporal variability of these water bodies: MAM: March – May 2024 JJA: June – August 2024 SON: September – November 2024 DJF: December 2024 – February 2025 This dataset provides a critical foundation for quantifying distributed water storage, evaluating irrigation resilience, and modeling hydrological and biogeochemical processes across diverse hydroclimatic region.