American Society of Civil Engineers

Optimal Layout of Sewer Systems: A Deterministic versus a Stochastic Model

by A. Freire Diogo, (corresponding author), (Asst. Prof., Dept. of Civ. Engrg., Univ. of Coimbra, Pólo II, 3030-290 Coimbra, Portugal E-mail: and Victor M. Graveto, (Chair Prof., Dept. of Civ. Engrg., Univ. of Coimbra, Pólo II, 3030-290 Coimbra, Portugal)

Journal of Hydraulic Engineering, Vol. 132, No. 9, September 2006, pp. 92-943, (doi:

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Document type: Journal Paper
Abstract: The optimization of a new or partially existing urban drainage system may be modeled as a subproblems sequence of layout and optimal design within the discrete search space. The design optimization, incorporating the optimal selection of the pumping stations, intermediate manholes, pipe sections, and installation depths, for a general system fixed layout in plan, is a high level sequential decision problem which may be efficiently solved deterministically through a multilevel dynamic programming model. The optimal general layout may be selected in a deterministic way by means of a simple economical comparison of all plan solutions having optimized designs, for small to medium sized systems (if the specific restrictions of the applications are appropriately exploited) in practicable computer time. For larger dimension networks, where it is clearly impossible to achieve plan optimization with full enumeration (which is a NP complete), stochastic search models can be used. For the subproblem layout, an effective enumeration model is presented; the results of a stochastic model proposed previously, using simulated annealing for an application example, are compared and discussed in detail.

ASCE Subject Headings:
Stochastic models
Urban areas