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RUNOFF AND CHANNEL FLOW CALCULATIONS <br /> PROGRAM NARRATIVE <br /> ALL RUNOFF AND CHANNEL FLOW CALCULATIONS WERE PERFORMED BY A <br /> PROGRAM DEVELOPED BY CF&I FOR USE ON A HEWLETT-PACKARD 41-C <br /> MICROCOMPUTER. THE CALCULATION PRINT-OUTS ARE INCLUDED <br /> WITH THIS REPORT . ALL FORMULAS FOR THE RUNOFF CALCULATIONS <br /> CAME FROM HYDROLOGY AND SFDIMENTOLOGY 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 /> IT WAS FIRST NECESSARY TO ESTIMATE RAINFALL INTENSITIES FOR <br /> THE RAINFALL DURATIONS WHICH WOULD EQUAL THE TIMES OF <br /> CONCENTRATION FOR 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 THE 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 /> INTENSITY CURVE FOP, STORMS IN THE WESTON, COLORADO, AREA <br /> 29 <br />