A residential urban area has the following proportions ofdifferent land use: roofs, 25 percent; asphalt pavement, 14precent; concrete sidewalk, 5 percent; gravel driveways, 7 percent;grassy lawns with average soil and little slope, 49 percent.Compute an average runoff coefficient using the values in Table13-2.
RUNOFF COEFFICIENTS FOR VARIOUS SURFACE Types of surface Watertight roofs Asphaltic cement streets TABLE 13 - 2 Portland cement streets Paved driveways and walks Gravel driveways and walks Lawns, sandy soil 2% Slope 2% - 7% Slope > 7% Slope Lawns, heavy soil 2% Slope 2% - 7% Slope > 7% Slope Coefficients (C) 0.70 -0.95 0.85 - 0.90 0.80 -0.95 0.75 -0.85 0.15-0.30 0.05 -0.10 0.100.15 0.15-0.20 0.13-0.17 0.18-0.22 0.25 -0.35
A residential urban area has the following proportions of different land use: roofs, 25 percent; asphalt pavement, 14 pr
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