***** creager.sdsu.edu   Error 01:   Please enter only a positive number as input data.  Try again. ***** "); } // branch 102 close elseif ($_POST["drainagearea"] > 0 ) // SET DEFAULT UNIT SYSTEMS { // branch 103 open $unitsystems = 0; // default value if(isset($_POST["unitsystems"])) // RESET UNIT SYSTEMS TO INPUT UNIT SYSTEM { // branch 104 open $unitsystems = $_POST["unitsystems"]; } // branch 104 close if ($unitsystems == 1) // DEFINE UNITS AND CONVERSION FACTORS { // branch 105 open $areaunits = "mi2"; $dischargeunits = "cfs"; $unitsystemsname = "U.S. Customary"; $areaconversion = 1.; $dischargeconversion = 1.; } // branch 105 close else { // branch 106 open $areaunits = "km2"; $dischargeunits = "m3 s-1"; $unitsystemsname = "SI (metric)"; $areaconversion = 1./2.58888; $dischargeconversion = 0.028316; } // branch 106 close $constant100 = 100.; // SET CONSTANTS IN CREAGER FORMULA $constant60 = 60.; $constant30 = 30.; // START CALCULATIONS $temp1 = pow($areaconversion*$_POST["drainagearea"],-0.048); //echo $temp1; //echo "

"; $temp2 = 0.894 * $temp1; //echo $temp2; //echo "

"; $temp3 = pow($areaconversion*$_POST["drainagearea"],$temp2); //echo $temp3; //echo "

"; $q100 = 46. * $constant100 * $temp3; $q60 = 46. * $constant60 * $temp3; $q30 = 46. * $constant30 * $temp3; if ($unitsystems == 0) { // branch 107 open $q100 = $q100 * $dischargeconversion; $q60 = $q60 * $dischargeconversion; $q30 = $q30 * $dischargeconversion; } // branch 107 close } // branch 103 close } // branch 101 close //--------------------------------------------------------------------------------------------------------------------------------------------------------------- ?>



    creager.sdsu.edu:   Calculation of flood discharge by the Creager formula

Spillway at Tucurui Dam, Brazil, rated at 110,000m3/s, the largest in the world.
Formula:

Q = 46 C A 0.894 A - 0.048

In SI Units (metric):
 Area A in km2;
Discharge Q in m3/s.
In U.S. Customary Units:
 Area A in mi2;
Discharge Q in cfs.
INPUT DATA:

Select:      

Drainage area A :        

OUTPUT:

Flood discharge (C = 100)    Q :    

Flood discharge (C = 60)    Q :    

Flood discharge (C = 30)    Q :    

            
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