Evaluating Polymeric Additives for Post‑Wildfire Erosion Reduction with Indoor Rainfall Simulation.

Ahmed A., Robichaud P.R., Hohner A.K., Akin I.D. 2025. Evaluating Polymeric Additives for Post‑Wildfire Erosion Reduction with Indoor Rainfall Simulation. Geotech Geol Eng (2025). 43, 104 DOI: 10.1007/s10706-025-03070-w.

Keywords: Green Ridge Fire, erosion control, xanthan gum, Polyacrylamide, rainfall simulation

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Abstract: Critically burnt slopes are treated after a wildfire to reduce erosion and the impacts of eroded soil and ash on downstream water quality. Conventional post-wildfire erosion mitigation methods including mulch, barrier, and seeding treatments have some drawbacks that may result in low efficiency. Polymeric materials, xanthan gum (XG) and polyacrylamide (PAM), are shown to be effective alternatives to the conventional methods in controlling postwildfire erosion of bare soil. This study evaluates the use of XG and PAM for controlling post-wildfire erosion when the soil surface is covered with hydrophilic ash, which is a common scenario after wildfires in moderate to high soil burn severity regions. Indoor rainfall simulation experiments are performed with soil and ash samples collected after the 2021 Green Ridge Wildfire near Walla Walla, WA to determine the effects of three concentrations (11, 33, and 60 kg/ha) of XG and PAM on infiltration, runoff, and sediment loss in ash-covered soil plots during three wet-dry cycles. Results show that XG and PAM treatments reduce the total sediment loss by up to 68% (XG) and 87% (PAM) during three wetting events for the study soil and ash. Both XG and PAM induce partial surface sealing, which results in higher runoff. However, with subsequent wettings, surface sealing reduces due to redistribution of XG and PAM. The results are explained through the distribution of water along plot depth, scanning electron microscope images, and binding of ash and additives.

Moscow FSL publication no. 2025a