Simulation of Earthquake Water Supply Performance

This paper describes a comprehensive hydraulic network model for earthquake simulation of the water supply system operated by the Los Angeles Department of Water and Power (LADWP). This model accounts accurately for flows and pressures in a heavily damaged system by special treatment of negative pressures, and provides methods for simulating pipeline leaks and breaks. Five different leak scenarios are modeled as a function of pipe diameter for various types of pipeline. The model accounts explicitly for 2200 km of pipelines, ranging in diameter from 300 to 3850 mm, associated with the LADWP trunk system, and simulates the remaining 9800 km of distribution pipelines by means of fragility curves relating demand to repair rate in the distribution network. Repair rate, in turn, is correlated with peak ground velocity and permanent ground deformation. The results of system simulation during the 1994 Northridge earthquake are presented, and compared with monitoring data collected by LADWP before and after the earthquake. The simulation is shown to produce flows at key locations that compare favorably with the monitoring data.