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Part 683 - Water Requirements <br />C0683.12(e) <br />One cfs for one hour is equivalent to 0.992 acre-inches per hour. <br />For ease in computation the conversion is taken to be: <br />' 1 cubic foot per second (cfs) is the same as one acre-inch per <br />hour. <br />Conveyance design Q = 2.08 ac-in/hr or 2.1 cfs. <br />The following formula can also be used: <br />Q = Peak daily Con. Use x 100 x acre = cfs needed <br />Field Efficiency x 24 <br />Solution: <br />Q = 0.25 x 100 x 120 = 2.1 cfs <br />60 x 24 <br />(f) The above example assumes a continuous water supply and <br />provides the minimum conveyance design capacity. When the water <br />delivery time is less than the irrigation frequency, the water <br />delivery time is used instead of the irrigation frequency when <br />using the gross application method. When using the Peak <br />Consumptive Use formula, the result.must be multiplied by the <br />ratio of: <br />Irrigation frequency (days) <br />Water delivery time (days) <br />Example: <br />In the preceding example, assume a water delivery time of <br />66 hours or 2.75 days. <br />Gross Application Method <br />120 acres x 6.7" = 800 acre-inches in366 hours <br />800/66 12.1 acre-inches per hour <br />Des i gn'Q = 12.1 cfs (use 12 cfs) <br />Peak Consumptive Use Formula <br />Q = 0.25 x 100 x 120 x 16 ='2.1 x 16 = 12 c;?s <br />60 x 24 2.75 .2.75 <br />C0683-8 <br />(CO210-V1-COIG, December 1988)