Question

Listed in Table Q2.1 below is the storm inflow hydrograph for a full reservoir that has an uncontrolled spillway for releasing flood water. Table Q2.1 Time (h) | 0 3 6 9 12 15 18 21 24 27 30 Inflow 2 104 204 226 213 185 158 136 118 102 89 (m/s) Time (h) 36 39 48 51 54 60 63 Inflow 78 68 56 47 39 30 22 15 9 4 2 (m/s) The storage and outflow characteristics of the reservoir and spillway are listed in Table Q2.2 33 42 45 57 Table Q2.2 For Students with Student Number Ending with 6 Outflow (m/s) 3.7 Height above spillway crest (m) Storage (106 m) 0.4 0.7 0.8 1.5 1.2 2.3 1.6 3.3 10.6 19.4 29 2.0 4.5 41 2.4 5.6 54 2.8 6.8 71 3.2 8.1 86 3.6 9.5 103 4.0 10.9 117 Determine the PEAK discharge of the outflow hydrograph. Assume that the outflow is 1 m/s at time t=0.

Answer 1

Time Index Time (h) 0 1,+j+1 (m3/s) 25/At-Q 25j+1/At +Qj+1 Inflow (m3/s) 60 100 Outflow Q:(m3/s) 57.0 1 2 2 61.3 160 332 3 4 80.6 232 300 4 6 532 5 6 8 10 520 1310 1930 820 1830 3240 7 12 8 115.0 169.6 348.2 768.3 1,119.2 1,147.9 1,012.3 752.1 14 1460 3390 2390 9 16 930 10 18 650 20,776 20,814 20,985 21,287 21,767 22,901 24,604 25,756 25,850 25,406 24,551 23,589 22,895 22,395 22,002 21,682 21,422 21,209 21,036 1580 20,936 21,146 21,517 22,107 23,597 26,141 27,994 28,146 27,430 26,056 24,551 23,589 22,895 22,395 22,002 21,682 21,422 21,209 11 20 650 12 22 481.0 13 24 347.0 14 26 250.4 15 28 196.2 16 30 159.9 32 130.3 17 18 34 106.2 19 36 86.5

As You can See above the Time, Flow, Inflow is Required Basically to calculate outflow.

1 4. A sample of the routing computations is given in table 7. The computations begin at a known value of outflow and inflow. The steps then are as follows: Entries in columns 1 and 2 are known. The first entry of outflow in column 5 is given. 2. Column 3 contains successive sums of values of inflow in column 2 for the particular time period under consideration and for the previous period. 28 3. Table 6 is entered with the known value of O, and the initial value of +0 is selected for column 4 of table 7. From the value in column 4 subtract twice the value in column 5 and enter the result in column 6. Add the value in column 6 to the value in column 3 of the succeeding time period and enter the result in column 4 for the new time period under consideration The new outflow discharge in column 5 is again obtained from the relation 28 of +0 with 0 in table 6. The steps 4, 5, and 6 are then repeated until the entire outflow hydrograph is generated. 8. The stage corresponding to this outflow is then selected from table 6 and entered in column 7 of table 7. TABLE 7.-- Routing through a reservoir Outflow + 5. 6. 7. Inflow cls 28 Time cs -0 Gage height (feet) (2) (3) (5) (6) (7) 1.18 1.18 0:00 :15 :80 :45 1:00 0 1.44 4.34 8.10 18.7 1.44 5.78 18. 24 27.6 -1.86 0 84 4.04 8.30 17.2 & 72 11.88 10. 29 10. 47 10. 10.82 11.6 37.5 1418 38.3 1:15 1:30 1:45 2:00. 2:15. 38,8 106 216 201 -11.5 - 21.0 -19.4 57 242 71.6 123 161 185 123.8 are 501 858 11.12 12.40 1335 12. W 14.31 507 611 2:30 155 208 3:00 8:15 3:30 645 684 594 545 495 1,128 1.350 1.514 1.661 732 950 1.116 1.223 1.278 14.30 14.64 14. 72 14.80 14.81 280 235 1.719 219 220 4:00 4:15. 4:30 211 188 166 116 129 446 309 353 310 274 1.724 1. 1. 1.284 1.245 1.161 1.050 1.474 212 14.81 14.80 14.77 14.70 14.81 14.51 14. 10 14.28 14.01 12.78 116 106 5:15. 5:30. 5:15. 6:00 1.158 800.4 199 191 181 186 149 70 10 410.4 202.4 184.4 1082 880 80.2 461.0 1630

As per the Calculations Assuming some Values like Chage of time, Period and Flow level

Time (h) Inflow 11 + 12 0 0 2. 2 #DIV/0! 0.15 3. 104 106 346.8167 0.3 6 204 310 340.3 0.45 9 226 536 2511.561 0.6 12 213 749 1775.6 0.75 15 185 934 1234.083 0.9 18 158 1092 878.6778 1.05 21 136 1228 648.669 1.2 24 118 1346 492.8667 1.35 27 102 1448 379.1278 1.5 30 89 1537 298.1667 1.65 33 78 1615 238.0136 1.8 36 68 1683 190.6889 1.95 39 56 1739 145.5397 2.1 42 47 1786 114.0048 2.25 45 39 1825 88.91667 2.4 48 30 1855 64.9 2.55 51 22 1877 45.68725 2.7 54 15 1892 30.47778 2.85 57 9 1901 18.63947 3 60 4 1905 9.666667 3.15 63 2 1907 6.324603 When Inflow is around = 226