Laboratory Experiments to Understand Post-Wildfire Processes on Soil Sealing for Hydrologic Fluxes in Complex Terrain

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It is well understood that floods and erosion following a wildfire can be costly to local communities. However, the specific processes that alter soil characteristics to increase flooding and erosion are not well understood. Soil sealing is one of the less studied post-wildfire processes because the peak impact of soil sealing occurs immediately after a wildfire when it can be difficult and dangerous to make field observations. However, this time period immediately after a wildfire also holds the highest risk for high damage flooding due to the lack of vegetation. To investigate the soil sealing processes that occur immediately after a wildfire, the investigators in this project will conduct laboratory experiments to simulate rainfall on burned soils and ash materials. The outcomes will provide new information about post-wildfire soil sealing processes with implications for forest management and disaster mitigation. Additionally, this project will support the development of technical skills for four college students and the development of a 4th and 5th grade science lesson on soil erosion.The overarching research question of this project is: how does the slope angle of a land surface affect soil sealing processes immediately after a wildfire, and how does this impact infiltration for consequent rain events? As slope angle increases, surface ash erosion rates will increase. As a result, it is hypothesized that soil surfaces that experience increased storage of ash will promote soil sealing processes that decrease infiltration during later rain events, thereby increasing runoff. To test this hypothesis, laboratory scale rainfall simulations will be conducted at a range of slope angles on simulated burned soil conditions. Investigators will observe the effect of slope angle by (1) quantifying the effect of slope angle on surface ash erosion and surface storage through rainfall experiments, and (2) determining the effect of ash retention, if any, on soil properties after rainfall experiments. This project is jointly funded by Hydrologic Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).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.