6.5.
Summary
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6.5· Summary
This chapter described how to include water quality management considerations in the water quantity planning model outlined in Chapter 2.
It was assumed that quality problems arose in free-flowing fresh water
river reaches, and a modern modification of the Streeter-Phelps equation
was used to calculate the profiles of biological oxygen demand (BOD) and
dissolved oxygen (DO) in each reach of the system. Two strategies for
controlling water quality were considered: low flow augmentation and
direct waste treatment at the polluting source.
The formulated optimization problem became: for a planning horizon
and a set of alternative waste water treatment projects select a period for
introducing each project so that the objective function is minimized while
meeting all the constraints (budgetary, technological, physical and water
quality standards). The proposed solution approach required that the
comprehensive water management problem be decomposed into two subproblems: (1) the water quantity problem of Chapter 2 and (2) the water
quality problem described in Section 6.3. The flows used in subproblem 2
are the outputs of subproblem 1 while the revenue from subproblem 2 is
fed back into subproblem 1.