Disentangling wildfire effects on the water cycle across wet mountain watersheds with varying subsurface storage

Wildfires are happening more often with increasing impact on communities and ecosystems. Wildfires affect water availability and quality. Recently, there have been big fires in forests where wildfires used to be rare, especially in the Pacific Northwest. People who manage forests need to know how these fires are impacting water resources. This research aims to understand how wildfires affect water production in Oregon’s Willamette National Forest by measuring water quantity and quality parameters in an area that has recently been burned to varying degrees. The project will support six students and train those students how to communicate findings to the public. The goal of this project is to understand how changes in vegetation cover (above ground) and soil structure (below ground) affect water production after wildfires in the wet montane forests of the Pacific Northwest. Wildfires can vary in intensity, sometimes burning only the vegetation and leaving the soil intact, or burning both the vegetation and the soil. These two scenarios impact snow accumulation and melt differently, which in turn affects the amount of water delivered to streams and how much water can be stored underground. This project will use data from the H.J. Andrews Experimental Forest in western Oregon. This includes 70 years of hydrometric data including streamflow and precipitation and unique pre-fire water chemistry data from various watersheds with different hydrological conditions. Planned activities include conducting snow surveys and geophysical measurements, and assessing soil infiltration and burn severity across multiple watersheds with varying levels of soil burn severity and vegetation mortality. Additionally, watershed modeling will be performed to compare how water moves through the study watersheds, how the streamflow is generated, and to evaluate sensitivity to the transition zone between snow and rain. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.