System analysis of wildfire-water supply risk in Colorado, U.S.A. with Monte Carlo wildfire and rainfall simulation

Water supply impairment from increased contaminant mobilization and transport after a wildfire is a major concern for communities that depend on surface water from fire prone watersheds. This work demonstrates the importance of considering water system characteristics when assessing wildfire risk to water supplies. Researchers used Monte Carlo simulation to assess wildfire-water supply impairment and disruption risks for a system of reservoirs and diversions in the Front Range Mountains of Colorado, U.S.A. The Monte Carlo simulation included realistic and stochastic representations of wildfire and rainfall activity, post-fire watershed response, and water supply sensitivity to sediment.

The results suggest that water supplies with large contributing areas are at highest risk of impairment due to their frequent exposure to wildfires sizeable enough to mobilize problematic quantities of sediment. The study also demonstrates that risk of system disruption is reduced by redundancy and magnified by dependency. The test scenarios show how disruption risk can be lowered with both exceptionally reliable large off-network reservoirs and alternative conveyance routes. In contrast, dependency among conveyance reservoirs nearly doubled the risk of conveyance disruption.

The full article can be found on the Risk Analysis journal website at https://onlinelibrary.wiley.com/doi/full/10.1111/risa.13762.