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solution_set_assign04 - CIVE 486 Assignment 4 Solutions 1...

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Unformatted text preview: CIVE 486 Assignment 4 Solutions 1 Problem 4.10 from text (p. 307): Use lag routing and hydrograph convolution to find the storm hydrograph at point 2. K = 20 min. The procedure to solve this problem is very similar to a question from the last assignment. The rainfall intensity is given (cm/hr), the 10-min unit hydrographs, and the total losses. Therefore convert the intensity into a UH multiplier and perform hydrograph convolution. Then add up the hydrographs from the three areas for a total hydrograph, lag by 20 min to get the output storm hydrograph. Subbasin A Time (min) Q (m 3 /s) 0.417 UH 1.5 UH 0.667 UH Total A 10 5 2.1 2.1 20 10 4.2 7.5 11.7 30 15 6.3 15.0 3.3 24.6 40 20 8.3 22.5 6.7 37.5 50 25 10.4 30.0 10.0 50.4 60 20 8.3 37.5 13.3 59.2 70 15 6.3 30.0 16.7 52.9 80 10 4.2 22.5 13.3 40.0 90 5 2.1 15.0 10.0 27.1 100 7.5 6.7 14.2 110 3.3 3.3 120 Subbasin B Time (min) Q (m 3 /s) 0.417 UH 1.5 UH 0.667 UH Total B 10 5 2.1 2.1 20 10 4.2 7.5 11.7 30 15 6.3 15.0 3.3 24.6 40 20 8.3 22.5 6.7 37.5 50 25 10.4 30.0 10.0 50.4 60 20 8.3 37.5 13.3 59.2 70 15 6.3 30.0 16.7 52.9 80 10 4.2 22.5 13.3 40.0 90 5 2.1 15.0 10.0 27.1 100 7.5 6.7 14.2 110 3.3 3.3 120 Subbasin C Time (min) Q (m 3 /s) 0.667 UH 1.667 UH 0.833 UH Total C CIVE 486 Assignment 4 Solution Page 1 of 14 10 16.7 11.1 11.1 20 33.4 22.3 27.8 0.0 50.1 30 50.0 33.4 55.7 13.9 102.9 40 33.4 22.3 83.4 27.8 133.5 50 16.7 11.1 55.7 41.7 108.5 60 27.8 27.8 55.7 70 13.9 13.9 80 Watershed Time (min) Outflow (m 3 /s) (20 min lag for A and B, normal C) 0.0 10 11.1 20 50.1 30 107.1 40 156.8 50 157.6 60 130.7 70 114.8 80 118.4 90 105.9 100 80.0 110 54.2 120 28.3 130 6.7 140 0.0 Storm Hydrograph at Point 2 0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 50 100 150 Time (min) Flow (m 3 /s) out of 2, 1 for getting hydrographs right, 1 for proper lagging CIVE 486 Assignment 4 Solution Page 2 of 14 2 Problem 4.5 from text (p. 306) a) Develop a recursive relation using the continuity equation and S-Q relationship for a linear reservoir See attached hand solutions b) Storage rout the hydrograph through the reservoir using t = 1 hr. Here use the equation developed in part a, substituting in values of t, k and I ave to get the value Q 2 . Initially, it is assumed that at t = 0, Q = 0. Therefore for the time step t = 1 hr, Q 1 (the previous time steps outflow = 0), I ave is the average inflow between time = 0 and time = 1 (50 m 3 /s) and the constants are given. To calculate the storage, either substitute the Q value into S = KQ, or use S = (Iave-Oave)* t....
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This note was uploaded on 02/05/2011 for the course CIVE 486 taught by Professor None during the Spring '11 term at Waterloo.

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solution_set_assign04 - CIVE 486 Assignment 4 Solutions 1...

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