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The following program was developed by Greg Lewicki <br />to determine the peak flow from small watersheds. <br />The procedures utilized were taken from the SCS TR-55 Manual. <br />Input drainage area in acres --> <br />2,2 <br />input average curve number --> <br />89 <br />input design precipitation in inches --> <br />1 .4 <br />THE SCS TR-55 METHOD IS USED TO CALCULATE THE PEAK RUNOFF BY FIRST DETERMINING <br />THE LAG TIME FOR THE WATERSHED AND THE TIME OF CONCENTRATION. <br />THE TC IS THEN RELATED TO A PEAK DISCHARGE IN CSM/INCH OF RUNOFF. <br />L8 .8 (S+1 )e .7 <br />lAG TIME IN HOURS=-------------------- <br />1900 Ye .5 <br />WHERE L=HYDRAULIC LENGTH OF WATERSHED IN FEET <br />Y=AVERAGE LAND SLOPE IN ~ <br />S IS A CURVE NUMBER PARAMETER GIVEN BY (1000/CN)-10 <br />DOES LAND SLOPE NEED TO BE CALCULATED(Y/N) --> <br />N <br />INPUT AVERAGE LAND SLOPE IN x --) <br />10 <br />INPUT HYDRAULIC LENGTH OF WATERSHED IN FEET --) <br />1150 <br />LAG TIME IN HOURS = 8,211615E-02 <br />TIME OF CONCENTRATION IN HRS = 8.211615E-02 <br />FROM THE SCS TR-55 CHARTS, THE PEAK DISCHARGE IN CSM/INCH = 905.0146 <br />PEAK FLOW = 905.0146 CSM/INCH X .0034375 SQUARE MILES X .5563415 <br />INCHES RUNOFF <br />PEAK FLOW = 1.730771 CFS <br />