CESU Study Agriculture Consumptive Use

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The scope of work is to assess consumptive water use (i.e. evapotranspiration; ET) from irrigated agricultural lands in the Upper Colorado River Basin. The following tasks have been identified by Reclamation staff and the Principal Investigator as priority tasks needed for crop ET modeling and remote sensing efforts in the Upper Colorado River Basin (Upper Basin): 1) Prepare ET demands model setup, calibration, and post processing steps for all subareas in the Upper Basin. For example: processing crop type data and developing crop masks; download and process soil data masked to the crop lands; calibration of basil crop coefficient (Kcb) curves to properly reflect historical planting; effective full cover, and harvest dates, and visualization of output for recognizing “good” or “bad” model runs or calibrations; and comparing model results (growing season start and end dates, ET rates, effective precipitation estimates, etc.) to previous studies. 2) Study ET demands with required input climate data, reference ET (ETo) calculations, and bias correction. Gridded climate data extraction for areas of interest, and bias correction to agricultural station data is needed to ensure that historical climate and ETo estimates are representative of agricultural conditions. 3) Study quality assurance and quality control from agricultural weather station data and processes agricultural station data to compute ETo. Compare gridded climate and ETo estimates to agricultural station based ETo to develop bias correction factors needed in task 2. 4) Develop rules by which crop classes such as 'pasture-high' and 'pasture-low' can be assigned to the grassland class which composes about 70% of the ag land in the UC Basin. 5) Evaluate the possibility of developing or evaluating existing maps of potentially irrigated lands. 6) Recommend a method for estimating shortages, winter time crop ET, and effective precipitation. 7) Compare potential crop ET estimates (e.g. from Penman Monteith ET Demands and Blaney-Criddle) to eddy covariance estimates of crop ET. 8) Recommending unified remote sensing of actual crop ET, and potential crop ET consumptive use methods. 9) Develop draft and final reports of findings and recommendations. 10) Participate in stakeholder meetings and workshops.

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