Watershed conditions change after wildfires.
Heavy rains in a burned area can create:
- More and faster runoff from rainfall, especially high-intensity storms.
- Large amounts of sediment, which may reduce storage capacity in a reservoir or clog drainages and culverts.
- Debris flows or downed timber, which may obstruct roadways and damage infrastructure.
The Washington Department of Ecology Dam Safety Office has developed some resources to be used as a starting point for qualified consultants to assess hydrology changes after a wildfire:
- Guidance for assessing post-wildfire hydrology
- Spreadsheet for calculating post-wildfire watershed parameters
The Natural Resource Conversation Service has also compiled some comprehensive guidance for performing post-wildfire hydrologic analyses. It includes case studies and examples.