GA-QP model to optimize sewer system design

Tze Chin Pan, Jehng-Jung Kao*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Sanitary sewer systems are fundamental and expensive facilities for controlling water pollution. Optimizing sewer design is a difficult task due to its associated hydraulic and mathematical complexities. Therefore, a genetic algorithm (GA) based approach has been developed. A set of diameters for all pipe segments in a sewer system is regarded as a chromosome for the proposed GA model. Hydraulic and topographical constraints are adopted in order to eliminate inappropriate chromosomes, thereby improving computational efficiency. To improve the solvability of the proposed model, the nonlinear cost optimization model is approximated and transformed into a quadratic programming (QP) model. The system cost, pipe slopes, and pipe buried depths of each generated chromosome are determined using the QP model. A sewer design problem cited in literature has been solved using the GA-QP model. The solution obtained from the GA model is comparable to that produced by the discrete differential dynamic programming approach. Finally, several near-optimum designs produced using the modeling to generate alternative approach are discussed and compared for improving the final design decision.

Original languageEnglish
Pages (from-to)17-24
Number of pages8
JournalJournal of Environmental Engineering
Issue number1
StatePublished - 12 Jan 2009


  • Algorithm
  • Optimization
  • Sewer design


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