A software program called Graphical Iterative Response Analysis of Flow Following Earthquakes (GIRAFFE) was developed at Cornell University to estimate earthquake performance of water supply networks. Developed as part of the MCEER-LADWP partnership, GIRAFFE estimates damage and functionality for heavily damaged water systems. The system is modified to simulate the occurrence of earthquake-caused damage. Damage to trunk lines is represented as distinct breaks and leaks. Damage to distribution lines is represented by increasing the demand at the demand node that represents the damaged distribution lines. This reflects the fact that distribution pipes with breaks and leaks in them will draw more water than normal from the trunk line network because water will spill into the ground rather than just serve customers.