Laserfiche WebLink
<br />18: <br /> <br />IRRIGATION WATER REQUIREMENTS <br /> <br />Irrigation water requirements vary with the type of crop, nature of the soil, <br />climatic conditions, farm practIces and other factors. For District 8, monthly <br />and seasonal Irrigation water requirements have bee" derived from data contained <br />in studies made by the U. S. Bureau of Reclamation. Estimated irrigation water <br />requirements for the Greeley-Fort<Mtrgan areaas reported by the Bureilu In Appendix II <br />of the Narrows Project Report were adjusted for differences in effective pre- <br />cipitation and temperature to arrive at the monthly and seasonal irrigation water <br />requirements summarized in Table 3 for the IS-year period from 1947 through <br />1961. lhese figures represent the quantity of water required at the farm head- <br />gate with an assumed farm efficiency of 60 percent. <br /> <br />.. <br /> <br />The IS-year study period Includes years of severe water shortage as well as <br />Some good water supply years and is considered a suitably representative period <br />for purposes of illustrating the variatIon and magnitude of irrigation water <br />requirements in District 8. Consumptive use estimates were derived by the <br />Bureau using a combination of the Thornthwaite and the Lowry-Johnson methods of <br />comput ing crap consumpt ive water use, The consumpt ive use at the crap was then <br />adjusted for the effective precipitation and variations in temperature between <br />the Greeley-Fort Morgan area and District 8 and these values further adjusted <br />by appl ication of the assumed farm efficiency of 60 percent. The monthly and <br />seasonal values summarized in Table 3 thus reflect the amount of water required <br />per irrigated acre at the farm headgate for irrigation in District 8. <br /> <br />Water requirements at the ditch headgate were determined by application of <br />ditch losses, derived by study of avai lable records and interviews with ditch <br />superintendents and others, to the farm headgale requirements and the estimated <br />irrigated acreage served by those ditches still in use for irrigation within <br />the district. Table 4 shows, for each of the 5 ditches presently delivering <br />water to irrigated lands, the estimated irrigated acreage and the assumed <br />ditch losses and, for each month of the irrigation season, the m~ximum, minimum, <br />median and mean water requirements based on the unit values contained in Table <br />3. The median value is the amount which is equaled or exceeded 50% of the time, <br />and is more meaningful than the average. From Table 4 it can be seen that <br />the range in monthly and seasonal Irrigation water requirements in District 8 <br />Is not particularly large. <br /> <br />" <br /> <br />Recorded diversions to ditches presently serv1ng irrigated lands for the <br />period 1940 through 1966 are contained in Tables 5 through 9. The figures <br />represent the total diversion to the dItch and thus includes both Irrigation <br />and municipal water. It can be assumed that since 1941 the proportion of <br />water diverted for municipal use has increased each year, while actual irrigation <br />has decreased. Sufficient data are not available to delineate respective <br />amounts and it Is impossible, therefore, to make a valid comparison between <br />the estimated range of water requirements at the ditch headgate and the amount <br />of water historically supplied, since part of the water supplied to each of <br />the ditches was used for municipal purposes. <br /> <br />" <br />