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only Mesa5 and the subareas in Gunnison County. Gunnison4 is the most affected with its IWR <br />changing from 3,180 acre-ft to 10,850 acre-ft, approximately a 240 percent increase. This corresponds to <br />the most significant change in the set of weights wherein the Paonia weather station was substituted for <br />the Crested Butte weather station to better represent the climate of Gunnison4. <br />A more detailed tabular result is included in Section 4.0 <br />3.0 CONCLUSIONS AND RECOMMENDATIONS <br />Depending on the level of detail desired, several different data sets were prepared for estimating IWR in <br />the Gunnison River basin. Smaller subareas may be chosen to increase the representativeness of the <br />weather stations. Sensitivity of the results to changes in the detail of the crop and soil characteristics was <br />evaluated. For instance, separately identifying the same crops on different soil types has proven to be <br />unnecessary. The annual IWR values may be more sensitive to varying planting/harvesting dates of <br />crops through the years, but not in terms of 5 to 10 year averages. <br />The IWR estimated by the SCS Blaney-Criddle method with enhancements was consistently lower than <br />the estimate of the SCS Blaney-Criddle without enhancements. This is mainly because of the <br />assumption that in the very first year of the estimation the soil moisture storage is at full capacity. The <br />other factors causing the difference are the winter precipitation contribution to soil moisture storage at <br />the beginning of the growing season, and the difference in the estimate of the effective rainfall. <br />The water supply information should be accounted for directly when estimating the actual consumptive <br />use. The CRDSS consumptive use program has this capability. In the past, the water supply information <br />was used indirectly. It was used to calculate water short areas that were then used as input requirements <br />to the CU model. The danger of this is that the temporal variability of the water supply and its impact to <br />the actual consumptive use may be lost because of the convenience of specifying short areas that are <br />constant from year to year. <br />4.0 SUPPORTING MATERIALS <br />Tables 5, 6, 7, and 8 show tabular summaries of the computation for the whole Gunnison River basin. <br />They are taken from gun_usbr_full.prj, gun_usbr_fulla.prj, gun_usbr_full_awc.prj, <br />gun_usbr_short_awc.prj, and gun_crdss_full_awc.prj output files of the CU model. <br />5 <br />A275 01.0995 1.14-22 Manguerra <br />