Estimation of County-Level Evapotranspiration and Irrigation using High-Resolution Planet Satellite Data

Abstract

Increased agricultural production has spurred the need for irrigated land in areas that may not be supported by surface water. Instead, groundwater is primarily used for irrigation in states such as Kansas to supplement the water needed for this land. The increase in groundwater use for irrigation may be contributing to areas of increasing groundwater decline, and more precise tracking of irrigation should take place on a larger, regional scale. This will allow for more effective tracking of irrigation trends and their possible effects. This thesis tests the challenges and possibilities of applying the Backward-Averaged Iterative Two-Source Surface temperature and energy balance Solution (BAITSSS) model with high-resolution PlanetScope (Planet) satellite data to the county of Cheyenne, Kansas. The drop of reflectance data observed in fields from Planet satellite data was used as a signal for the first irrigation event, and the model subsequently ran from there. The results from this demonstrate that the BAITSSS evapotranspiration (ET) is comparable to the OpenET model; BAITSSS overall estimates a higher ET in agricultural areas compared to OpenET. However the irrigation results are underestimated, but there are many limiting factors that could be adjusted with further consideration. More research should be conducted toward the efficient and effective running of the BAITSSS model on a larger region.