CIVE 445 - ENGINEERING HYDROLOGY

SPRING 2008 - MIDTERM 2 - SOLUTION

PROBLEM 2

To convolute the 2-hr unit hydrograph with the effective storm pattern defined at intervals of 3 hr, it is necessary to change the unit hydrograph duration to 3 hr. We use the S-hydrograph method to change the 2-hr UH to 3-hr UH.

To calculate the flood hydrograph, for 6 cm, it is 6 times; for 12 cm, it is 12 times (lagged 3 hr).

Time2-hr UH2-hr SH Lagged 3 hr3-hr UH6×UH12×UH
(lagged 3 hr)
Flood
hydrograph
(hr)(mm/hr)mm/h (ha)(m3/s)(m3/s)(m3/s)(m3/s)
000 00.00000
155 03.3320020
21515 010.0060060
33035 023.331400140
46075 546.6728040320
570105 1560.00360120480
660135 3566.67400280680
755160 7556.67340560900
845180 10550.003007201020
935195 13540.002408001040
1025205 16030.00180680860
1115210 18020.00120600720
125210 19510.0060480540
130210 2053.3320360380
140210 2100.000240240
150210 2100.000120120
160210 2100.0004040
170210 2100.00000
420- -420.002520
[= 420×6]
5040
[= 420×12]
7560
[= 420×18]

Problem 3

 
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