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<br />. H. Stream Reach Simulation <br /> <br />1. ,Hydraulic Simulation Techniques <br /> <br />"'-- <br />--J <br />c..'1 <br />00 <br /> <br />Several hydraulic simulation techniques are routinely used in <br /> <br /> <br />assessment of i nstream flow requi rements. The fami ly of hydraul i c <br /> <br /> <br />simulations most promising in the assessment of discharge manipula- <br /> <br />tion is generally termed "backwater curve "calculation (8). Several <br /> <br /> <br />computer programs are available which can predict the hydraul ic <br /> <br /> <br />parameters of depth and velocity for different discharges (9). The <br /> <br /> <br />CIFSG methodology makes use of a program designed by the BR (1968) <br /> <br />termed "Pseudo" or "WSP" (water surface profi 1 e). <br /> <br />. <br /> <br />Very briefly stated, the WSP (Pseudo) program calculates the water <br /> <br /> <br />surface elevations and velocities in rivers, using the standard- <br /> <br /> <br />backwater approach. The first cross-section (the control) is <br /> <br /> <br />located where stage/discharge relationship is known or can be esti- <br /> <br /> <br />mated using Manning's formula. The total discharge is calculated by <br /> <br /> <br />proportioning the flow by the ratio of conveyance factors. Velocity <br /> <br /> <br />in various segments of the cross-section are then calculated using <br /> <br /> <br />the proportion of flow in each segment. <br /> <br />. <br /> <br />46 <br />