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<br />Values for the coefficient C are obtainable from standard hydraulics <br />handbooks, but model tes ts for eva 1 uati ng C shoul d be made ~Ihere unusual <br />conditions exist and discharge determinations are critical, particularly <br />for partial gate openings. Reference 8 provides information on calcu- <br />lation of rating curves for outlet works. Where possible, outlet <br />discharge rating curves should be checked by prototype measurements <br />dOl/nstream as soon after project construction as is feasible. <br />Where very large release capacities are required for flood control <br />it might not be economically feasible to follo~1 the normal procedure of <br />providing outlet capacity for full flood-control releases when the reser- <br />voir stage is at the top of the conservation pool. If full release capa- <br />city is not provided, it should be rer:Jembered that reduced outlet capacity <br />must be accompanied by increased storage capacity, or else the flood <br />control effectiveness will be reduced. The proper balance among outlet <br />capacity, storage capacity, and degree of flood protection provided can <br />be obtained through studies of costs and benefits and consideration of <br />other factors such as safety and minimum protection standards. Such stud- <br />ies would include comprehensive flood routings as discussed in Chapter 4. <br />There are occasions where local inflows above downstream damage <br />locations are so large as to severely restrict the releases that can <br />safely be made from the reservoir during critical flood periods. In <br />such cases, outl et capac i ty substanti ally below dOl.mstream channel capa- <br />cities might be adequate. In order to select the best release capacity, <br />comprehensive flood routings discussed above should include typical <br />sequences of floods long enough to assure that expected sequences of <br />floods can be adequately regulated. <br /> <br />5-02 <br />