Assessing Post-Earthquake Firefighting Capacity of Water Distribution Networks Considering Isolation Valve Operations

The firefighting capacity of water distribution networks following earthquakes is essential for achieving the Sustainable Development Goals on resilient infrastructure and sustainable communities. Isolating broken pipes to curb leakage can preserve water supply, but the effects of such operations on post-earthquake firefighting remain incompletely understood. Here, we develop an improved valve closure decision method for post-earthquake firefighting that balances leakage reduction with water transmission capacity. Using this method as a basis, we examine how ground motion intensity, domestic water curtailment, firefighting flow, the number and spatial distribution of fires, valve layout, and valve closure policy jointly affect firefighting. A case study on a benchmark network shows that the valve closure scheme generated by the decision method reduces leakage by about 60–75% under spatially dispersed fires and the N − 1 valve layout. Compared with no isolation, it also raises delivered firefighting flow from under 20% to over 80% of the design value. On average, these schemes deliver flow 5–10% below the optimal scheme. Valve placement, however, has a strong influence: under the N − 2 layout, alternative placements can alter delivered flow by 10–20%. Adverse conditions—widespread pipe leakage caused by strong ground motion, hydraulic overload from clustered fires or firefighting flow surges, and sharp pressure reductions at fire nodes in low-pressure zones owing to excessive flow or leakage—can prevent the schemes from improving firefighting flow. These findings indicate that effective firefighting requires a combination of rational valve placement and closure schemes with seismic retrofitting of pipes and fire hazard mitigation.