M.Sc Student | Zeidan Mohamad |
---|---|

Subject | Multi-Objective Optimization for Trading off Operational Cost, Leakage, and Water Age in Water Distribution Systems |

Department | Department of Civil and Environmental Engineering |

Supervisor | Professor Avi Ostfeld |

Full Thesis text |

This research proposes a multi-objective optimization model for minimizing water age, leakage, pressure, and operational costs, under consumer demands and system constraints. The developed methodology links a multi-objective genetic algorithm with EPANET.

The network is first divided into segregated district metered areas (DMAs) allowing to effectively control leakage problems. In addition, segregation of a looped WDS to a number of independent DMAs improves the water distribution network management as it simplifies water balance calculations and reduces water security risks, as contaminants movement in the network are better controlled.

The proposed
methodology incorporates the following stages: (1) __Mapping the water
distribution system__: the distribution system is mapped into an undirected
graph, G= (V, E) in which the vertices V represent the consumers, sources and
tanks, and the edges E represent the connecting pipes, pumps and valves. (2) __Communities
structure identification__: subdividing the graph G into
clusters using the community structure method proposed by Clauset et al. (2004)
(the method uses modularity as an indicator to the quality of the resulted
graph divisions into clusters). (3) __Dendrogram cutting__: the dendrogram
(i.e., the outcome of stage 2) indicates the hierarchical community structure
of the water distribution network. It is up to the decision maker to define the
limits of the community nodes number or consumers demand, and thus the location
of cutting the dendrogram to meet those constraints. (4) __Communities
isolation__: isolating the clusters to reduce the interaction between them
and thus limit contaminants movement in the system through closing some of the
feed lines that connect between the clusters. The isolation process starts from
the smallest bridge pipe in diameter until the last one, closing part of them
using a heuristic method. (5) __Implanting new pump operation scheduling,
using a genetic algorithm__ to competitively reduce the water leakage, the
water age and the operational costs while satisfying the customer requirements
for minimum pressure. A multi-objective optimization problem is solved,
resulting in a multi-objective Pareto front. The proposed methodology is
demonstrated through a couple of case studies of increasing complexity.