SPDSS_Task59-1_Develop Locally Calibrated Blaney-Criddle Crop Coefficients

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altitude portion above 6,500 feet and the Upper Plains calibrated coefficients are used below. As with monthly data, daily climate data used for the ASCE Standardized method need to be reviewed for reasonableness. Based on inspection and discussions with CoAgMet, negative solar radiation and vapor pressure values, as well as unreasonably low wind values, were removed prior to using the daily data. Inspecting data graphically helps identify such extreme values. Methods described in "The ASCE Standardized Reference Evapotranspiration Equation" (ASCE, 2005) provide comprehensive data inspection and adjustment guidelines. While the Upper Plains and Lower Plains calibrated coefficients closely approximate the ASCE Standardized method, it is recognized that use of the modified Blaney- Criddle method will produce results that are somewhat smoothed and not fully reflective of the differences between years seen with the application of the ASCE Standardized method. The Upper Plains and Lower Plains locally calibrated coefficient were created using daily data from climate stations located in agricultural settings. For SPDSS modeling efforts, these crop coefficients will be applied with monthly NOAA data from stations located in both agricultural and urban settings. Based on further investigation described in the Task 81.2 memorandum, this is reasonable for the SPDSS modeling efforts. Where to find more information ^ The Task 53.2 -Collect and Fill Missing Monthly Climate Data memo provides additional information on selected key climate stations. ^ The Task 58 -Review Previous Estimates of Potential CU memo provides additional information on several potential consumptive use equations. ^ The Task 81.2 -Consumptive Use and Water Budget Technical Peer Review Meeting Follow-Up memo provides additional information based on technical peer review of this task. References ASCE Manuals and Reports on Engineering Practice No. 70, Evapotranspiration and Irrigation Water Requirements, Edited by Jensen, M.E., Burman, R.D., and Allen, R.G., 1990. Carlson, N. C., Pollara, J.R., and Le, T. (1991). "Evapotranspiration in High Altitude Mountain Meadows, in Grand County", Report for the Board of Water Commissioners, City and County of Denver, CO. November, 1991. Division of Water Resources (2003), "CUSUM, Summary Report, Irrigation Consumptive Use and Data Collection Program, 1983-2003", Division of Water Resources, Water Division VI. Also relied on were miscellaneous communications with Andy Schaffner, Water Commissioner for Districts 57 and 58, about the nature of the program. Task59_l.doc (updated January 11, 2008) 21 of 32