Long-term Monitoring of Global Lakes and Reservoirs using MODIS/VIIRS observations

Freshwater lakes and reservoirs are critical components of the Earth's water and carbon cycles, yet our understanding of their long-term global dynamics—especially in relation to climate variability and water management—remains limited. The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites, as well as the Visible Infrared Imaging Radiometer Suite (VIIRS) from the Suomi National Polar-orbiting Partnership (SNPP) satellite and NOAA-20 satellite, offer unique capabilities to generate long-term datasets that can be used for studying these dynamics. The reflectance data facilitates the estimation of surface area, which can be used to infer storage, while the Land Surface Temperature (LST) measurements improve simulations of vertical thermal mixing and heat storage, thereby enhancing the accuracy of evaporation rate estimates.

In this presentation, we introduce the recently developed MODIS/VIIRS Global Water Reservoir (GWR) product suite, which provides estimates of area, elevation, storage, evaporation rate, and evaporation loss for 164 large reservoirs. The GWR products contain reservoir storage and evaporation data at 8-day and monthly temporal resolutions. We also evaluate the consistency between MODIS and VIIRS-based GWR products to ensure continuity across 25 years of MODIS observations. Additionally, we have expanded the dataset to include over 2,700 large lakes and reservoirs.

Using the GWR product and its extended dataset, we demonstrate key applications, such as monitoring reservoir-based droughts, comparing long-term evaporative losses, and assessing storage variation trends at basin, regional, and global scales. These insights are crucial for better understanding the long-term global dynamics of the lakes/reservoirs, and addressing the challenges and knowledge gaps related to the interactions between lakes/reservoirs, climate variability and extremes.