OPTIMAL RESTORATION STRATEGY OF A WATER PIPELINE NETWORK IN SURIGAO CITY, PHILIPPINES
Keywords:
water lifeline, seismic event, Horn’s Algorithm, minimal spanning tree, penalty functionAbstract
Quick recovery of water services immediately after an earthquake is critical. This is to
minimize hazards to environmental sanitation and consequent health problems caused by the lack of potable
water supply. It is necessary therefore that water lifeline operators establish restoration strategies to deal with
damage scenarios in their respective concession areas specifically during extreme seismic events. The recent
6.7 magnitude earthquake in Surigao City due to the movement of the Philippine Fault Zone: Surigao
segment underscored this need. However due to the complexity of the network a systematic restoration
sequence that minimizes restoration time and maximizes delivery of water service should be employed. In
this research, the authors employed Horn’s algorithm to determine the optimal restoration strategy of a
pipeline network in Surigao City, Philippines. The repair sequence starts with the determination of a minimal
spanning tree of the given pipeline network. The water source is designated as the root of this tree while the
nodes represent the water demand at specific areas. The edges of the tree structure representing the pipelines
connect the nodes. The assigned numeric value or weight of an edge (link) denotes the time to repair that
specific pipeline. This value is a function of the length of the pipeline. The results show that an optimal job
sequence may be carried out by considering maximal ratios of expanding family trees within the network. A
least penalty function is a consequence of the optimal repair job sequence.
