LIT194-Handbook of TII.pdf - Diamond Head Sprinkler Supply

SlopeSlope, as used in irrigation, is a measure of the incline of an area. It can be described as 1) apercent, formula “A”, 2) a degree, formulas “B” and “C”, or 3) a ratio, formula “D”. The greaterthe incline, the greater the tendency for runoff.A) The percent of slope can be determined by dividing the net change in elevation between twopoints (Rise) by the horizontal distance between those two points (Run).Point “B”S= RiseRunRiseWhere:Point “A”S = the percent of slopeRise = the net elevation change in elevation between two pointsRun = the horizontal distance between the two pointsNote: The units for Rise and Run can be any unit of linear measure, but they must be thesame for both the Rise and Run.Example:What is the slope for a bank 40 ft. wide (run) on which the elevation at the top (point “B”) is20 ft. higher than the toe of the slope (point “A”)S = 20 S = 0.50 or 50%40B) The degree of slope describes a slope as the angle of the slope (at “A”) from the horizontalplane. This method is useful when taking field measurements as “c” represents themeasured distance up a slope and “a” equals the elevation change.RunPoint “B”sin A =a/cPoint “A”cAngle at “A”aWhere:A = the anglea = the height of the right trianglec = the length of the hypotenuse of a right triangleHorizontal PlaneExample:a = 20 feetc = 44.72 feetsin A = 20 sin A = 0.4472 A = 26° 34'44.72®Handbook of Technical Irrigation Information3