Wildfire and Extreme Rain Intensify Erosion and Sediment Flow, USGS-led Study Shows

Read the study in Earth and Space Science

By Pacific Coastal and Marine Science Center August 28, 2024

In a warming climate, increased wildfire activity coupled with extreme rain events is causing significant erosion, leading to heightened sediment flow in rivers. This phenomenon has critical implications for water resource management and infrastructure maintenance.

Location map of the general study area, Upper Carmel River, central California coast.

A recent study led by scientists at USGS characterizes the magnitude of sediment production in watersheds affected by such events, focusing on the Carmel River watershed on the central California coast.

The study aimed to quantify the sediment generated by wildfire followed by extreme rain and flooding. By measuring the volume of sediment deposited within a reservoir fed by the Carmel River watershed, researchers could assess the rate of sediment export post-fire and flood. Their findings indicated that the sediment production rate following these events was significantly higher than the long-term average for the region.

This surge in sediment poses challenges for water systems and infrastructure. Sediment accumulation in reservoirs reduces their storage capacity, and excessive post-fire sediment runoff can hinder the operation of water systems as well as damage roads and infrastructure. Therefore, understanding sediment dynamics in the wake of wildfire and extreme weather is crucial for effective resource management and infrastructure protection.

Read a related press release: Erosion following wildfire has increased in California since 1984

To validate their observations, the scientists compared their results with predictions from the Water Erosion Prediction Project (WEPP) model. They found that the model accurately forecasted the amount of sediment that would be produced, demonstrating its utility in predicting erosion outcomes in similar environments.

These findings are particularly relevant for regions with Mediterranean-type climates such as coastal California, characterized by wet winters and dry summers, where steep watersheds are common. The study underscores the importance of preparing for increased sediment flow due to climate-induced changes in wildfire and precipitation patterns.

By providing a clearer understanding of sediment dynamics post-wildfire and extreme rain, this research offers valuable insights for managing the impacts of climate change on water resources and infrastructure, and can inform strategies to mitigate the adverse effects of increased erosion and sediment transport in vulnerable watersheds.

Read the study, Post-Fire Sediment Yield From a Central California Watershed: Field Measurements and Validation of the WEPP Model, in Earth and Space Science.