Keywords: Seismic performance. Water supply systems. Lifelines. Los Angeles Department of Water and Power (LADWP). Pipelines. Probabilistic analyses. Body waves.
Abstract: This report described an evaluation process for simulating the seismic performance of large geographically distributed water supply systems and characterizing their performance in terms of reliability and serviceability. The evaluation process makes use of probabilistic seismic hazard analysis tools, theoretical and empirical relationships of pipeline responses, hydraulic analysis of heavily damaged water networks, and multi-scale simulations of complex water systems. The process provides information for decision makers to assess the economic and social impacts of lifeline disruptions due to earthquakes, and works in combination with a computer code, Graphical Iterative Response Analysis for Flow Following Earthquakes (GIRAFFE) developed by the authors to simulate heavily damaged pipeline networks and presents the simulation results in GIS format. The framework for decision-making presented in this report describes five basic activities: seismic hazard characterization, system definition, system component response evaluation, global system response evaluation, and consequences assessment. The methodology was applied to evaluate the seismic performance of the water supply operated by the Los Angeles Department of Water and Power (LADWP). The results of the analysis show that the five water districts in the LADWP have significantly different seismic risks and deteriorate to various extents after a 24-hour period following an earthquake. These differences in serviceability and reliability are consistent with the geographical position of the districts in relationship to the seismic faults and their capacity for water storage.