Field-Scale assessment of Water Use change over the Lower Mississippi Alluvial Plain

The Lower Mississippi Alluvial Plain (LMAP) is one of the most productive regions in the United States, with large area of corn, soybean, rice and cotton planted. Associated with the intensified agricultural activities, this region has been experiencing a rapid decrease of ground water table due to groundwater withdraw. This will threaten the sustainability of water supply and may get even worse under the changing climate. To solve the issue with groundwater depletion, it is important to understand how the withdrawn groundwater is currently used by various crop types and different fields. Evapotranspiration (ET) represents the land surface water use. Field-scale ET retrieved from satellite data has been heavily evaluated by comparing with flux tower observations and proved to be efficient for agriculture management impact study, crop water use accounting, crop yield estimation, and irrigation scheduling. This work will assess both the trend and spatial pattern of ET in the LMAP region at field scale. The energy balance model based on remotely sensed data will be used to estimate field-scale daily ET with key inputs from satellite observations. Through the OpenET project, with six widely used ET models implemented into Google Earth Engine to leverage the strong cloud computational power, field-scale large area ET over the LMAP region will be estimated. This work will provide critical information to address the challenge of water resource sustainability under the changing climate over the environmental vulnerable area.