Table17.1Floodroutingcomputations
|
Change
|
in storage
|
∆s dur-
|
∆ingt
|
4 3(10m)
|
|
InflowTrialOutflowAverageOutflow
|
volumereservoirrateQ
|
∆duringtleveltimetrateQ
|
43343∆(10m)attimet(m/s)fort(10m)
|
3(m)(m/s)
|
|
|
|
volume
|
∆duringt
|
|
|
|
|
|
outflow
|
0
|
|
|
|
|
|
at
|
|
|
|
|
|
|
0
|
|
|
|
|
Average
|
inflowrateQ
|
∆fort
|
3(m/s)
|
|
|
|
|
i
|
|
|
|
IRRIGATION AND WATER RESOURCES ENGINEERING
13
|
|
Okay
|
High
|
Okay
|
High
|
Okay
|
High
|
Okay
|
Low
|
Okay
|
Low
|
Okay
|
Okay
|
Okay
|
Okay
|
Low
|
Okay
|
12
|
|
100.20
|
100.75
|
100.70
|
101.42
|
101.40
|
102.00
|
102.00
|
102.40
|
102.35
|
102.55
|
102.60
|
102.70
|
102.70
|
102.60
|
102.45
|
102.45
|
11
|
11000.00
|
11167.46
|
11636.30
|
11623.12
|
12391.92
|
12365.93
|
13174.90
|
13158.53
|
13739.59
|
13753.47
|
14081.84
|
14121.59
|
14285.68
|
14276.31
|
14129.00
|
13883.85
|
13888.52
|
10
|
|
167.46
|
468.84
|
455.66
|
768.80
|
742.81
|
808.97
|
792.60
|
581.06
|
594.94
|
328.37
|
368.12
|
164.09
|
–9.37
|
–147.31
|
–245.15
|
–240.48
|
9
|
|
3.54
|
13.56
|
26.74
|
62.80
|
88.79
|
161.23
|
177.60
|
268.54
|
254.66
|
348.43
|
308.68
|
341.71
|
351.37
|
341.71
|
322.55
|
317.88
|
8
|
|
9.84
|
37.67
|
74.27
|
174.43
|
246.64
|
447.86
|
493.34
|
745.94
|
707.40
|
967.85
|
857.44
|
949.18
|
976.04
|
949.18
|
895.98
|
883.00
|
7
|
0
|
19.68
|
55.66
|
128.85
|
220.00
|
364.43
|
531.29
|
622.25
|
869.63
|
792.55
|
1143.15
|
922.32
|
976.04
|
976.04
|
922.32
|
869.63
|
843.67
|
6
|
|
100.2
|
100.4
|
100.7
|
101.0
|
101.4
|
101.80
|
102.00
|
102.50
|
102.35
|
103.00
|
102.60
|
102.70
|
102.70
|
102.60
|
102.50
|
102.45
|
5
|
|
171.0
|
482.4
|
|
831.6
|
|
970.2
|
|
849.6
|
|
676.8
|
|
505.8
|
342.0
|
194.4
|
77.4
|
|
4
|
|
475
|
1340
|
|
2310
|
|
2695
|
|
2360
|
|
1880
|
|
1405
|
950
|
540
|
215
|
|
Inflowrateat
|
time t
|
3(m/s)
|
3
|
100
|
850
|
1830
|
2790
|
|
2600
|
2120
|
1640
|
|
1170
|
730
|
350
|
80
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Time
|
interval
|
∆t
|
(hrs)
|
2
|
|
1
|
1
|
1
|
1
|
1
|
|
1
|
1
|
1
|
|
1
|
1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Time t
|
|
|
(hrs)
|
1
|
0
|
1
|
2
|
3
|
|
4
|
5
|
6
|
|
7
|
8
|
9
|
10
|
SPILLWAYS
567
3000
2000
1000
0 10 20 30 40 50
2s
( Ñt + QO) in 1000 cu.m/s
Fig. 17.4
( i) At the beginning of the first time interval ( i.e., the routing period), both s1 and Qo,1 are equal to zero if the storage dealt with in this interval is treated as the storage above the spillway crest level. Therefore, Eq. (17.3) yields
-
|
|
2s2 + Q
|
o,2
|
= (Q
|
+ Q
|
)
|
|
|
|
|
|
|
∆t
|
i,1
|
i,2
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Since both Q
|
and Q
|
are known (Fig. 17.1),
|
2s2
|
+ Q
|
o,2
|
is determined.
|
|
|
|
i,1
|
i,2
|
|
|
|
|
|
∆t
|
|
|
|
|
|
|
|
|
|
|
|
|
( ii) Read the value of Qo,2 ( i.e., the outflow rate at the end of the first time interval, i.e.,
-
t = ∆t) for known value of
|
2s2
|
|
+ Qo,2
|
from Fig. 17.4.
|
|
|
∆t
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
(iii) obtain (
|
2s2
|
− Qo,2 ) (i.e., the value of (
|
2s2
|
|
− Qo ) at the beginning of the second time
|
|
|
|
|
∆t
|
|
|
|
|
|
|
|
|
∆t
|
|
|
|
|
|
|
interval) which is equal to [(
|
2s2
|
+ Q
|
|
|
) −
|
2Q
|
].
|
|
|
|
|
|
|
|
|
|
|
|
|
|
∆t
|
o , 2
|
|
|
o,2
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
F
|
2s3
|
|
|
|
I
|
|
= dQ i ,2
|
F 2s2
|
I
|
|
(iv) For the second time interval G
|
∆t
|
+ Qo,3 J
|
|
+ Qi,3 i + G
|
− Qo,2 J
|
|
|
|
|
|
H
|
|
|
|
K
|
|
|
|
H ∆t
|
K
|
|
Since, R.H.S. is known, one can determine L.H.S., the corresponding Qo,3 ( i.e., the outflow
|
|
F 2s3
|
I
|
|
rate at the end of the second time interval i.e., t = 2∆t), and the value of G
|
|
− Qo,3 J i.e., the
|
|
|
|
|
|
H ∆t
|
K
|
|
value of
|
2s
|
− Qo at the beginning of the third time interval (t = 2∆t).
|
|
|
∆t
|
|
|
|
|
|
|
|
568 IRRIGATION AND WATER RESOURCES ENGINEERING
( v) Repeat step ( iii) for subsequent time steps till the end of the last time interval.
Flood routing problem of Table 17.1 has been solved using ISD method in Tables 17.2 and 17.3 and Figs. 17.4 and 17.5.
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