Laserfiche WebLink
Direct comparison of the previous water budget investigation results to the RGDSS results is made <br />difficult due to: <br />Different study areas (Figure 1: San Luis Valley, Alamosa Basin, Closed Basin, RGDSS <br />Ground Water Area), <br />Different study periods (1924-69, 1950-80, 1970-87, 1950-97, and variable periods <br />representing long-term averages). <br />2. Based on our review, the water budget items with the greatest uncertainty are ground water inflows <br />from the San Juan Mountains and consumptive use estimates from evapotranspiration. Given the <br />magnitude of these water budget items, a 10 to 20% estimation error can result in a significant <br />amount of water. <br />Of the five water budget investigations, the Hearne and Dewey water budget was the most complete <br />in addressing the water budget components of the entire basin and using a consistent period for each <br />water budget item to determine an average. However, the water budget did not balance for the <br />Alamosa Basin because the computed residual water budget item, ground water outflow, was <br />computed to be 345 kaf/yr, which they determined to be unreasonable given the aquifer <br />characteristics. We agree with the authors that the large imbalance can be attributed to estimation <br />errors of other items such as San Juan ground water inflows and evapotranspiration. <br />4. Direct comparison of the non-beneficial consumptive use component between the RGDSS Ground <br />Water Area water budget analysis and the previous five water budget investigations is made difficult <br />because of the large discrepancy in beneficial consumptive use estimates. Based on our review of <br />the five previous water budget investigations, we believe the beneficial consumptive use component <br />reflected total potential consumptive use -the amount of water the irrigated crops would use if they <br />had a full water supply available from a combination of effective precipitation, irrigation water, and <br />shallow ground water. The RGDSS supply-limited consumptive use analyses estimated abasin-wide <br />crop shortage of approximately 20 percent. <br />rg_task8-1_2001-08.doc 19 of 19 Apri16, 2001 <br />