Understanding the Downstream Impacts of On-Farm Reservoirs

On-farm reservoirs play a critical role in crop irrigation. They store water during the wet season for subsequent use for crop irrigation during the dry season. In the U.S. alone, there are an estimated 2.6 million such reservoirs. However, storing this water has poorly understood impacts on downstream hydrology and ecosystems. The amount of water stored also varies from year to year based on the precipitation rates of the wet seasons. A new study led by Vinicius Perin of North Carolina State University, partially conducted while Perin was an intern in Planet’s Professional Services team, utilizes Planet data in combination with European Space Agency Sentinel-1 radar and Sentinel-2 optical data to understand the variations in these reservoirs at sub-weekly timescales across the seasons. Many of these reservoirs are smaller than 50 ha in surface area, so high resolution imagery is required to accurately determine their extents. Analyzing over 700 separate reservoirs, Perin et al. created a method involving Kalman filters to monitor reservoir surface area change over time. “[T]he approach presented in this study [has] the potential to enhance water conservation plans by allowing better assessment and management” of on-farm reservoirs, the authors note in their paper. “[T]his information can be used for water irrigation management recommendations aiming to increase water use efficiency.”

The full study can be found in Remote Sensing of Environment.