44
2. Formulating
the
Problem
Fig. 2.2 Each project may represent one dam or a different sized dam at one site.
Ν + 8, Ν + 9) may ever be built. Figure 2.2 shows how these three projects may represent, for exjample, three different sizes of a dam at a specified
dam site. In addition
]
^max
Σ Xye < 1
for all j = N + l,... 9 M
(2.5)
i.e., project j can be built in only one of the years, if it is built at all. Also,
\ jt = 0 or 1
(2.6)
as defined in Section 2.2.
2.3.3. Dam Revenue
Equation
The revenue for the operation of each reservoir can be represented by
Xw = //(£*fi./i > J Σ AjmQimt, Dm)
for ally
(2.7)
m
where D vt is the quantity of water supplied for irrigation from reservoir
j in month i of year t } fj the return function for reservoir j 9 Im the amount
of imported water supplied to reservoir j in month i of year f, Q imt the flow
in stream or canal m during month i of year t, and Sm the storage volume
of water in reservoir j at the beginning of month i of year i, i.e., the carryover storage. The form of equation can be the same for each reservoir, but
the coefficients will differ. The simplest form of the equation would be a
linear sum of the revenues less the costs; a nonlinear equation introduces