1,2,3,4,1,2- 1Institute of Geo-Hydroinformatics, Hamburg University of Technology, Hamburg, Germany
- 2United Nations University Hub on Engineering to Face Climate Change at the Hamburg University of Technology, United Nations University Institute for Water, Environment and Health (UNU-INWEH), Hamburg, Germany
- 3Center for Geospatial Analytics, Clark University, Worcester, MA 01610, USA
- 4Graduate School of Geography, Clark University, Worcester, MA 01610, USA
Small agricultural reservoirs are a critical, yet poorly documented component of managed water storage systems, supporting irrigation and livestock water demands (Aminzadeh et al., 2025). Due to small size (often <0.1 km²) and strong temporal variability of agricultural reservoirs driven by evaporative losses and frequent withdrawals (Aminzadeh et al., 2024, 2018), they are commonly overlooked in the existing global inventories of inland water bodies. We present the first comprehensive global, seasonally resolved dataset of small agricultural reservoirs derived by integrating Sentinel-2 optical indices and Sentinel-1 radar backscatter. The product includes four seasonal layers for March 2024-February 2025 (MAM, JJA, SON, DJF). Water bodies are detected independently in optical and radar imagery using an edge-aware, locally adaptive dynamic thresholding approach. We identified more than 5 million reservoirs globally, with the highest density in China, the United States, and India. Validation against ~2,000 independently delineated reservoirs shows strong area agreement (R² = 0.92), enabling forward updates and retrospective back-casting toward a multiyear global record.
References
Aminzadeh, M., Friedrich, N., Narayanaswamy, S., Madani, K., Shokri, N., 2024. Evaporation Loss From Small Agricultural Reservoirs in a Warming Climate: An Overlooked Component of Water Accounting. Earth’s Future 12, e2023EF004050. https://doi.org/10.1029/2023EF004050
Aminzadeh, M., Lehmann, P., Or, D., 2018. Evaporation suppression and energy balance of water reservoirs covered with self-assembling floating elements. Hydrology and Earth System Sciences 22, 4015–4032. https://doi.org/10.5194/hess-22-4015-2018
Aminzadeh, M., Narayanaswamy, S., Nevermann, H., Zampieri, M., Hoteit, I., D’Odorico, P., AghaKouchak, A., Madani, K., Shokri, N., 2025. Water storage paradox of reservoir expansion and evaporative losses in the MENA region. Sci Rep 15, 34297. https://doi.org/10.1038/s41598-025-21859-w
How to cite: Govindaiah Narayanaswamy, S., Aminzadeh, M., Alemohammad, H., and Shokri, N.: Global distribution of small agricultural reservoirs and their seasonal dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22569, https://doi.org/10.5194/egusphere-egu26-22569, 2026.
