Post-earthquake water demand modeling of water distribution systems considering population redistribution

Abstract

To estimate the water demands of water distribution systems (WDSs) after earthquakes, a new method is proposed in this study to model the post-earthquake water demands of different user nodes in WDSs, relying on urban land use maps and resident population distribution. The method considers three key restoration phases: rescue, refuge, and reconstruction. The spatial distribution of post-earthquake population in various land parcels is first determined based on the empirical models of earthquake evacuees and casualties. Then, the water demands of a land parcel are estimated by multiplying the parcel's area by the corresponding post-earthquake water demand indices, along with the sum of water demands for ordinary residents, injured individuals, and evacuees in the land parcel. To allocate the water demands of different land parcels to user nodes, the service areas of different user nodes are determined using Thiessen polygons. Finally, the water demands of a land parcel are allocated to user nodes based on the percentage of the parcel's area within the service areas of the user nodes. The proposed method is applied to a WDS currently operating in a typical city located in high seismic intensity region. The numerical results, in terms of the water demands of the whole network and different user nodes, are compared with those obtained from two existing methods. The influence of seismic intensity on the water demands of different user nodes is also investigated in this study. The numerical results show that in the proposed method, the post-earthquake water demands of WDSs increase in the three restoration phases, which is consistent with the post-earthquake survey of WDSs after the 2008 Wenchuan earthquake, indicating the rationality of the proposed modeling method.