Laserfiche WebLink
- Irrigation practices as percent of irrigated acreage per ditch system or water <br />district <br />- Application efficiency per type of irrigation practice <br />3. Review published data on on-farm irrigation efficiencies in the San Luis Valley and <br />other areas <br />4. Contact AGRO engineering principals to gather information from their previous <br />studies and field experience <br />5. Suggest appropriate maximum application efficiencies to use based on irrigation <br />methods <br />Results -Conveyance Efficiencies <br />The large ditch companies, shown in Table 1, were interviewed by the Surface Water <br />Contractors. In some cases, the contact for the ditch company was able to indicate a <br />percentage of flow loss experienced along the main canal, portions of the main canal, or <br />throughout the ditch system. As indicated in the table footnote, either the length of the <br />main canal was provided by the ditch company, was measured from USGS County maps <br />showing the major ditches, or was extracted from the RGDSS GIS canal coverage. Canal <br />lengths provided in the User Interview Notes were verified from the USGS mapping. <br />Main canal capacities are those reported in Hydrobase. The average soil available water <br />content beneath the main canal was determined from the Rio Grande Soil AWC GIS <br />mapping. <br />Canals in the Rio Grande are estimated to flow through the lower soil layer. Permeability <br />for this layer was determined for each MRCS soil polygon using the methodology <br />described in Appendix C for the average available water content. The average <br />permeability beneath the main canal was determined from the resulting GIS mapping. <br />In 1972, the results of a gain/loss study were published in the Colorado Water Resources <br />Basic-Data Release No. 22 - Hydrologic Data for the San Luis Valley, Colorado. This <br />report included flow measurements taken at various locations along the Empire Canal, <br />the Rio Grande Canal, and the Farmers Union Canal. <br />The Empire Canal results were not considered, because only a portion of the canal was <br />measured. Flow measurements for the Rio Grande Canal were taken after the first month <br />of irrigation at points along the main canal. The measured 31 percent loss was used in <br />our analyses, as footnoted on Table 1, because no information was provided during the <br />user interviews regarding later season losses on the Rio Grande Canal. <br />Flow measurements were also taken after the first month of irrigation at points along <br />Farmers Union Canal. The measured 32 percent loss was also used in our analyses, as no <br />more recent information was provided during the user interviews. <br />appendB_cropcu_6-2004.doc B-3 of B-19 June 2004 <br />