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<br />10 <br /> <br />sediment routing is then made by a two-step finite-difference algorithm. The <br />first step is to con.,ute the change in sediment volume between two cross <br />sections: <br /> <br />t:.V1. = (Qs - Qs + qs' )t:.t <br />i+l i ... i <br /> <br />.... (2-12) <br /> <br />The second step is determination of the change in cross-section area at each <br />cross section. The model assumes that one-quarter of t:.V. is deposited or <br />1 <br />eroded in the upstream half of the segment between sections i and i+l, while <br />three-quarters of t:.V. 1 is deposited or eroded in the downstream half of the <br />1- <br />reach between sections i and i-I. Therefore, when qSR, is neglected, (2-8) can <br />be exp ressed as <br /> <br />t:.Ab. <br />1 <br /> <br />1 <br />= <br />1 - A <br /> <br />lQ _Q _lQ <br />2 si+l si 2 si_l <br />t:.x. + t:.x. t:.t <br />1-1 1 <br /> <br />.... (2-13) <br /> <br />new channel geometry. The method used <br />at a point to the local conveyance. <br /> <br />vertical, t:.Z., is computed as follows: <br />J <br />t:.A <br />kR, + kR,+1 bi <br />!J.Z. = K <br />J . y '+1- y. 1 <br />1 J J- <br /> <br />is to <br />The <br /> <br />cross section to determi ne the <br />relate the bed-elevation change <br />elevation change at the j-th <br /> <br />Finally, the model distributes t:.Abi over the <br /> <br />.... (2-14) <br /> <br />where <br />kR, and kR,+1 = conveyances of the incremental areas to the right and <br />left of the j-th vertical <br />Yj+l and yj-l= lateral coordinates of the (j+l)st and (j-l)st <br />vert i ca 1 s <br />Ki = total conveyance of the i-th cross section <br /> <br />6. Data Requirements: <br /> <br />KUWASER requires the following input data: <br />(1) Number of cross sections and individual reach lengths. <br />