Comparing methods to estimate consumptive use with remote sensing in California's Sacramento-San Joaquin Delta

Multiscale Assessment of Agricultural Consumptive Water Use in California's Central Valley

“…Among the planning areas, the discrepancies ranged from -53.4% to −18.5%, with the most significant disagreement (<−50%) occurring in the southern and center-east of the San Joaquin Valley (planning areas 704, 708, 709 in Figure 1b). Similarly, previous studies in the Sacramento-San Joaquin Delta, a subset of the Central Valley, showed that remote sensing estimates are lower than CALSIMETAW's estimates by 6-24% (Medellín-Azuara et al, 2018;Paul et al, 2017). Over this Delta area, our crop-specific Priestley-Taylor method in this study estimated 1.20 tera-liter in 2016, very similar to the DISALEXI's estimate of 1.16 tera-liter in the water year 2016; both were about 80% of CalSIMETAW's estimates of 1.49 tera-liters, based on the published data summary table in Medellín-Azuara et al (2018).…”

“…Most sites were located in the Sacramento‐San Joaquin Delta region was also employed in the Delta Consumptive Use Comparative Study (Medellín‐Azuara et al., 2018) supported by the California State Water Resources Control Board Office of the Delta Watermaster and other agencies. Less expensive surface renewal systems were deployed over 14 sites for corn, alfalfa, and pasture.…”

“…We first modified, calibrated, and evaluated the refined semiempirical Priestley‐Taylor method (Jin et al., 2011) over major California crops, using the Landsat Analysis Ready Data (Dwyer et al., 2018). This approach further built upon an earlier version adapted for evapotranspiration estimation in Sacramento‐San Joaquin Delta (Medellín‐Azuara et al., 2018). The method was chosen for this study based on its relatively good performance and computational efficiency for large‐scale applications (Medellín‐Azuara et al., 2018).…”

“…This approach further built upon an earlier version adapted for evapotranspiration estimation in Sacramento‐San Joaquin Delta (Medellín‐Azuara et al., 2018). The method was chosen for this study based on its relatively good performance and computational efficiency for large‐scale applications (Medellín‐Azuara et al., 2018). The automated workflow for regional applications was applied to assess the spatial patterns of evapotranspiration across the Central Valley and among dominant crop types and to analyze water use changes between 2014 and 2016 water years.…”

“…DisALEXI has been further developed to estimate evapotranspiration at 30-m resolution, by bringing in additional higher spatial resolution thermal data from Landsat (Anderson et al, 2012(Anderson et al, , 2004Knipper et al, 2018;Norman et al, 2003). A recent comparative study of crop evapotranspiration estimates over the Sacramento-San Joaquin Delta showed that DisALEXI estimates had an RMSE of 1.43 mm day −1 and mean bias of 0.13 mm day −1 while the calibrated METRIC prepared by the Irrigation Training & Research Center had an RMSE and mean bias of 2.55 and 2.06 mm day −1 , respectively (Medellín-Azuara et al, 2018). Another biophysical model, Breathing Earth System Simulator (BESS) (Baldocchi et al, 2019;Jiang & Ryu, 2016;Ryu et al, 2011), couple surface energy balance, photosynthesis, and stomatal conductance processes, to estimate evapotranspiration, forced by biophysical parameters from Moderate Resolution Imaging Spectroradiometer (MODIS) 8-days 1-km observations.…”