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Run~~ff and Channel Flow Calculations <br /> <br />Program Narrative <br />All runoff and ~~hannel flow calculations were performed by a <br />program developed by CFI for use on a Hewlett-Packard 41-C <br />micro-computer. The calculation print-outs are included <br />with this report. All formulas for the runoff calculations <br />came from Hydrology and Sedimentology of Surface Mined <br />Lands by C.T. Haan and B.J. Barfield, (1978). Rainfall data <br />was from Technical Paper No. 40, Rainfall Frequency Atlas <br />of the United States by the U.S. Department of Commerce, <br />Weather Bureau, (1961). <br />( In determining Peak runoff flows for the various drainages _. <br />i it was first necessary to estimate rainfall intensities for <br />the rainfall durations which would equal the times of <br />concentration f~~r the drainage baisns to be evaluated. That <br />is to say that every drainage characteristically has a <br />definite time in which the entire surface is saturated and <br />contributing runoff to thz collecting drainage. This time <br />is dependant on the intensity of the storm. <br />Characteristically storm events have a higher intensity as <br />their duration decreases. With the time of concentration <br />and the required storm intensity being dependant on one <br />another, trial times of concentration were tested to <br />calculate the rainfall intensity required to saturate the <br />area. The time of concentration and the calculated <br />intensity most nearly matching the rainfall duration- <br />22 <br />