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<br />The average end area method assumes the area of the midsection is the <br />average of the area of the two bases so equation (5) reduces to: <br /> <br />v = Y:.h(A 1 + A 2) <br /> <br />. (6) <br /> <br />For the first increment of storage, A 1 is zero so the pyramid equation can <br />be used to compute the volume below the first contour: <br /> <br />v = Voh(A 2) <br /> <br />(7) <br /> <br />where h is the distance from the minimum elevation in the reservoir to <br />the first contour and A 2 is the area of the first contour. <br /> <br />2.3. OMAHA DISTRICT METHOD. <br /> <br />The Omaha District procedure for determining reservoir capacity versus <br />elevation is an offshoot of the traditional "average-end-area" method, adjusted to <br />include factors that take into account the nonuniformity of reservoir contours. For this ' <br />procedure portions of the reservoir bounded by one or more sediment rangelines and <br />the dam crest contour are considered as segments for determining storage capacity. <br />Those portions of a segment situated between consecutive contours are referred to <br />as sub-segments. The four steps required in developing this method are as follows: <br /> <br />L <br /> <br />v" <br />1/ 2 ( A~ + A;;\ <br /> <br />(1) <br /> <br />Vf ~ <br /> <br />, (A~+Ail)L <br />2 <br /> <br />(2) <br /> <br />Vf ~ <br /> <br />Vo <br />..1 _II. <br /> <br />(Ai+Ail) <br /> <br />(3) <br /> <br />@c;oc; <br /> <br />(Ao+Ao) <br /> <br />Let f ~ <br /> <br />Vo <br />AI All <br />0+ 0 <br /> <br />7-74 <br />