| Description |
Irrigation accounts for approximately 80% of consumptive water use in the U.S., making evapotranspiration (ET) an important measure for agricultural water management. Estimation and prediction of spatially varied ET using measured data is difficult. Remote sensing approaches have been used to extrapolate point measurements of ET to watershed-scale ET. Mapping ET at high resolution with internalized calibration (METRIC) is a satellite-based remote sensing surface energy balance model developed to estimate ET from agricultural areas. However, it needs substantial human intervention for calibration, and this causes variability in final ET products. This dissertation first quantifies this variability in ET due to the calibration process. Second, since METRIC ET provides only an estimate of consumptive use, cropping system models (CSM) have been developed to estimate crop management parameters to maximize yield. Since these CSMs are difficult to parameterize at watershed-scale, this dissertation provides a framework for assimilating METRIC results into CropSyst so that the CSM management parameters can be estimated. This framework was successfully applied to corn crop in the Yakima County, Washington. For the third part of this dissertation, METRIC was used to understand and improve water management strategies using the Lower Yakima River Basin as a case study. This work demonstrated how spatially varied consumptive use data from METRIC could complement traditional diversion records and help understand the differences in management of agricultural water among entities during drought and nondrought periods. Better planning and management of agricultural water resources requires future predictions of consumptive use. For the fourth part of this dissertation, METRIC ET was used with climate, crop, and watershed properties to create a statistical (Random Forest) model to predict consumptive use into the near future (assumed to be around 2 years). This model was developed and its near-term future prediction ability was successfully demonstrated for the agricultural area of Lower Yakima River Basin. This dissertation lays the groundwork for using METRIC without the need for significant expert intervention. It demonstrates the use of long-term METRIC results, to understand multiyear trends, parameterize cropping system models and statistically predict future consumptive use to support better management of agricultural water resources. |
