Lab 6 solutions

Lab 6 solutions - CEIE 340 Lab 6 Solutions YHK Problem 1....

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CEIE 340 Lab 6 Solutions YHK Page 1 of 3 Problem 1. Problem 7.45 on page 419 The weighted curve number for this area is computed by determining the curve number (CN) for each of the land uses in the area. The curve numbers for the various land uses and soil types are found using Table 3.18 on pages 161-162. First equation 3.50 is used to calculate the CNw for imperviousness. Equation 7.22 is then used to compute the weighted CN for the entire area. Here are the calculations: Area (acres) Area Fraction Soil Group Imperviousness (%) CN P CN w Fraction x CN 4.0 0.20 B 24 61 70 14.00 6.0 0.30 C 18 74 78 23.40 7.0 0.35 B 60 61 83 29.05 3.0 0.15 C 75 74 92 13.80 20.0 1.00 Weighted CN for the entire area = 80.25 The weighted CN for the area can then be used to determine the runoff depth using Table 7.13 on page 391. Here are the results for rainfall depth of 5 inches: Rainfall Depth [in] CN Runoff Depth [in] 5 80 2.89 To compute the runoff depths using the weighted Q method, the runoff depth for each land use type must be determined. The weighted average of this runoff depth is then computed. Here are the calculations for this approach:
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This note was uploaded on 11/11/2009 for the course CEIE 340 taught by Professor Choudhury during the Spring '09 term at George Mason.

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Lab 6 solutions - CEIE 340 Lab 6 Solutions YHK Problem 1....

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