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Part 683 - Water Requirements <br />C0683.12 (a) (1) <br />C0683.12 Average daily and peak period consumptive use rates. <br />(a) While other factors may have a minor influence on the <br />rate of consumptive use for a given period of time, air <br />temperature and net depth of irrigation application have the <br />greatest influence. <br />(1) Temperature._ An analysis of daily mean air temperature <br />records for any month at any location will show that the mean <br />temperature for the warmest consecutive 5-day period will be <br />greater than that for the warmest 10-day period. Likewise, the <br />mean temperature for the warmest consecutive 10-day period will <br />be greater than that for the warmest 15-day period, and so on. <br />All will be greater than the mean monthly temperature. It is <br />obvious that the shorter the period is in days, the.greater"will <br />be the mean temperature, and therefore, the greater will be the <br />consumptive use rate. <br />(2) Net Irrigation Application. The length of the period <br />is that number of days in which the normal net irrigation <br />application will last. Thus, smaller net irrigation applications <br />will last for smaller periods of time and will result in a <br />greater daily use rate for given time period and conversely <br />higher net irrigation applications will result in a lower.use <br />rate. <br />(3) Daily Use Rates. Table C0683.51 shows average daily <br />consumptive use rates as related to monthly use and net <br />irrigation application. When the computed monthly consumptive <br />use rate is for the peak use month, the tabular value is the peak <br />period daily use rate. <br />(4) Peak Period Consumptive Use Rate. Information on peak <br />period rates of consumptive use is needed to properly design <br />irrigation systems. It is used to determine the minimum capacity <br />requirements of main and lateral canals, pip4lines, and other <br />wate'r.'c.onveyance or control structures. The peak period rates of <br />water used by crops also influence the administration of streams <br />and reservoirs from which irrigation water supplies are obtained. <br />(b) In irrigation system design, the peak period of <br />consumptive use is the period during which the weighted average <br />daily rate of consumptive use of the various crops grown in the <br />project area is at a maximum. Different crops ma'y,have their <br />peak rates of use at different times. Therefore, some crops may <br />not be using water at their maximum rate during the project peak <br />period. <br />C0683-6 <br />(CO210-VI-COIL, December 1888)