Page 73 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

JWCL344_ch02_029-060.qxd 8/2/10 9:14 PM Page 36

36 Chapter 2 Water Sources: Surface Water
Assuming that inflow and drafts are repeated cyclically, in successive sets of
T years, a procedure called sequent peak was developed for determining minimum storage
for no shortage in draft based on two needed cycles. Example 2.1 illustrates the procedure.

EXAMPLE 2.1 CALCULATION OF REQUIRED STORAGE FROM RUNOFF RECORDS

From the recorded monthly mean runoff values shown in column 2, Table 2.2, find the required
storage for the estimated rates of draft listed in column 3, Table 2.2.

Solution 1 (U.S. Customary System):
2
2
2
Conversion factors: 1 MG/mi 1.461 ML/km ; 1 MGD mi 1.461 MLD km 2
Table 2.2 Calculation of Required Storage (Example 2.1) a
Order Storage
of Recorded Estimated S Waste, Reservoir
Months Runoff, Q Draft, D Q D (Q D) P T b W State c

(1) (2) (3) (4) (5) (6) (7) (8)
1 94 27 67 67 67 0 R
2 122 27 95 162 162 0 R
3 45 30 15 177P 1 176 1 L
4 5 30 25 152 151 0 F
5 5 33 28 124 123 0 F
6 2 30 28 96 95 0 F
7 0 27 27 69 68 0 F
8 2 27 25 44 43 0 F
9 16 30 14 30 29 0 F
10 7 36 29 1T 1 0 0 E
11 72 33 39 40 39 0 R
12 92 30 62 102 101 0 R
1 94 27 67 169 168 0 R
2 122 27 95 264 176 87 L
3 45 30 15 279P 2 176 15 L
4 5 30 25 254 151 0 F
5 5 33 28 226 123 0 F
6 2 30 28 198 95 0 F
7 0 27 27 171 68 0 F
8 2 27 25 146 43 0 F
9 16 30 14 132 29 0 F
10 7 36 29 103T 2 0 0 E
11 72 33 39 142 39 0 R
12 92 30 62 204P 3 101 0 R
a 2
Runoff Q, draft D, and storage S are expressed in MG/mi .
b
P peak; T trough.
c
R rising; F falling; L spilling; E empty.
2
Conversion factor: 1 MG mi 1.461 ML km 2