Lab 10 Solutions

Lab 10 Solutions - CEIE 340 Problem 1. Lab 10 Solutions YHK...

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CEIE 340 Lab 10 Solutions YHK Page 1 of 5 Problem 1. A unit hydrograph is the result of 1 inch of excess rainfall over the entire watershed. The volume of direct runoff equals the volume of excess rainfall. To compute the volume of direct runoff, find the area under the unit hydrograph. The calculations are shown here: Time [minutes] Flow Rate [cfs] Volume of Direct Runoff [ft 3 ] 0 - 5 0 0 5 - 10 20 4,500 10 - 15 70 12,000 15 - 20 50 10,500 20 - 25 25 6,000 25 - 30 10 3,000 30 - 35 5 1,500 TOTAL = 37,500 The watershed area equals the volume of direct runoff (or excess rainfall) divided by the depth of the rainfall (1 inch or 1/12 ft). Watershed Area = 37,500/(1/12) = 450,000 ft 2 or 10.33 acres Problem 2. The table below shows the calculations to determine the direct runoff from the rainstorm. Direct Runoff [cfs] Due to Rainfall Excess in Period Period Start Time [min] End Time [min] Rainfall Excess [in] 1 2 3 4 5 6 7 8 9 10 11 Total 1 0 5 0.0 0.0 0.0 2 5 10 0.1 0.0 0.0 0.0 3 10 15 0.4 0.0 1.5 0.0 1.5 4 15 20 0.0 0.0 4.0 6.0 0.0 10.0 5 20 25 0.6 0.0 3.5 16.0 0.0 0.0 19.5 6 25 30 0.3 0.0 2.0 14.0 0.0 9.0 0.0 25.0 7 30 35 0.1 0.0 1.0 8.0 0.0 24.0 4.5 0.0 37.5 8 35 40 0.0 0.0 0.5 4.0 0.0 21.0 12.0 1.5 0.0 39.0 9 40 45 0.0 0.0 2.0 0.0 12.0 10.5 4.0
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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 10 Solutions - CEIE 340 Problem 1. Lab 10 Solutions YHK...

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