The handbook of Technical irrigaTion informaTion - Hunter Industries

Slope Reference ChartPercent, Angle and RatioSlope Reference Chart: Percent, Angle and RatioTables% Angle Ratio00˚10 5˚ 43' 10: 120 11˚ 19' 5: 130 16˚ 42'33 18˚ 16' 3: 140 21˚ 48'50 26˚ 34' 2: 160 30˚ 58'67 33˚ 50' 1.5: 170 35˚ 0'80 38˚ 40'90 42˚ 0'100 45˚ 0' 1: 1hHorizontal DistanceSee Column No. 1h = vertical rise in feetPercent of grade or slope: Equals vertical rise infeet per 100' of horizontal distance= Angle of slope: Angle of inclination withrespect to horizontal plane (ie)tan = h/horizontal distanceRatio of slope = horizontal distanceh0.5: 163˚ 27'62˚ 15'60˚ 57'59˚ 32'58˚ 0'56˚ 19'54˚ 28'52˚ 26'50˚ 42'47˚ 44'200190180170160150140130120110Maximum Precipitation Rates for SlopesThe maximum precipitation values listed below are those suggested by the United States Department ofAgriculture. The values are average and may vary with respect to actual soil condition and condition of ground cover.Maximum Precipitation Rates: Inches per HourSoil Texture 0 to 5% slope 5 to 8% slope 8 to 12% slope 12% + slopeCover Bare Cover Bare Cover Bare Cover BareCoarse sandy soils 2.00 2.00 2.00 1.50 1.50 1.00 1.00 0.50Coarse sandy soils overcompact subsoils1.75 1.50 1.25 1.00 1.00 0.75 0.75 0.40Light sandy loams uniform 1.75 1.00 1.25 0.80 1.00 0.60 0.75 0.40Light sandy loams overcompact subsoils1.25 0.75 1.00 0.50 0.75 0.40 0.50 0.30Uniform silt loams 1.00 0.50 0.80 0.40 0.60 0.30 0.40 0.20Silt loams over compactsubsoil0.60 0.30 0.50 0.25 0.40 0.15 0.30 0.10Heavy clay or clay loam 0.20 0.15 0.15 0.10 0.12 0.08 0.10 0.0647