WSP07488 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I of lateral capacity as a representative condition. From diversion rate corresponds to a seepage rate of about comparison, at a typical Keesee Ditch diversion of 13 correspond~ng seepage rate determined from Figure B-1 would percent. Figure 2, this 8 percent. By to 14 cfs, the also be about 8 fQrt Lyon Canal In t~e Fort Lyon Canal case, a report was obtained from the State Engineers .Office files entitled "Interim Report - Results of First Phase Seepage Testing - Fort Lyon Canal" by Nelson, Haley, Patterson and Quirk, Inc. dated June 17, 1976. This report used a number of canal flow measurements at various pOints along the Fort Lyon Canal for the estimation of seepage loss rates. The resulting seepage losses were estimated to average about 0.3 percent per mile for the first 62-mile portion of the canal. The report also estimated the unit rate of seepage through the wetted perimeter 'of the canal as averaging 0.36 feet per day for the Fort Lyon Canal. This seepage rate estimate is more useful as a comparison than seepage as a percentage of diversions because it is essentially independent of the size of the canal. Assuming a semi-circular canal cross section, and converting to seepage based on water surface area (as used for the Keesee Ditch anal~sis), the corresponding Fort Lyon seepage rate would be about 0.57 feet per day, as compared to the calculated rate for the Keesee Ditch of 0.685 feet per day. As with the Colorado Canal situation, the Keesee Ditch corresponds more closely in 'size and length to some of the Fort Lyon Canal laterals than to the main cana~ (which is over 100 miles long). Exhibit NN from the Fort Lyon Canal case file (copy attached) is an operational flow chart for the overall Fort Lyon system and includes estimates of actual diversions, deliveries, losses and consumptive use for an average year. Ignoring the main canal system, the calculated consumptive use portion of the 135,800 af delivered to the laterals was 91,600 af, or an actual irrigation efficiency of 67 percent. The indiv~dual components of lateral loss (10 percent) and farm loss (25 percent) oorrespond to actual delivery and field efficiencies of 90 percent and 75 perqent respectively. Given ,that the Fort Lyon values are actual efficiency estimates, and not estimates of maximum irrigation efficiency, they must represent either a water-short or highly efficient irrigation system. As a comparison, the original Keesee Ditch analysis (HRS Vol. 1 report) calculated an actual consumptiv~ use efficiency of 59 percent based on a maximum irrigation efficiency of 70 percent. SUMMARY A detailed analysis of maximum irrigation efficiency was performed for the Keesee' Ditch using published methodology and site specific data for the Keesee Ditch system. This analysis resulted in monthly estimates of maximum irrigation efficiency to be used in an analysis of historical consumptive use. A comparison to seepage loss and irrigation efficiency estimates made for two other Arkan~as River ditch systems indicated comparable results. 6