An initial feasibility study for Texas
Accurate estimates of crop evapotranspiration (ET) are needed annually to determine irrigated water use per county and to feed into irrigation demand estimates state-wide. Remote sensing has the potential to improve the accuracy of crop ET (water out) and precipitation (water in) by increasing the spatial and temporal resolution state-wide. However, operational crop ET is in its early stages and currently requires significant expertise to produce quality estimates. Our goal is to assess the feasibility of the current state-of-the-science remote sensing approaches to quantify crop ET across the climatically and agriculturally diverse landscape of Texas. We use a variety of metrics to assess the various needed components including the ET algorithms by accuracy tiers and complexity, as well as other requirements such as gridded weather data. Each of these components was evaluated to assess their respective feasibility for state-wide implementation.
We are currently implementing 2 remote sensing algorithms, SEBS and METRIC, as Tier 2 and Tier 4, respectively, over 8 counties in Texas to determine crop ET estimates. We will also assess Landsat image quality for each climate zone and various time integration methods needed to develop annual totals of crop irrigation requirements (CIR).