Assessment of Maintenance Strategies for Bio-stabilization of Mudslides on Wildfire-affected Slopes

Research Team: Ingrid Tomac (lead) and Jonathon Chavez de Rosa

UC Campus(es): UC San Diego

Problem Statement: Wildfires in California have increased due to climate change, poor forests maintenance, and human factors. Post-wildfire mudflows frequently occur during rain events on burn scars due to loss of vegetation, change of surface morphology, and soil surface hydrophobicity. One of the approaches to prevent erosion - triggered mudflows and debris flow on burned, hydrophobic soil is to use a temporary biopolymer cover dispersed on slopes from drones. Although previous studies showed the effects of biopolymers on improving sand shear strength and decreasing permeability, a limited number of studies use biopolymers as a post - wildfire slope mitigation technique. Furthermore, little research focused on enhancing erosion resistance by covering hydrophobic slopes with pure Xanthan gum (XG) without exploring alternative application approaches..

Project Description: This research focuses on gaps in the literature regarding the effects of sand type and particle size, rain intensity, slope angle, and XG concentration, including the coupling of relevant parameters, for mitigation of post-wildfire slopes, as well as advantages and limitations of the method. Furthermore, this research investigates environmental effects by subjecting untreated and treated slopes to outside elements for six months, looking at the cumulative impacts of wind, natural rain, and animals. This project conducted an experimental performance assessment of environmentally friendly biopolymers for stabilizing hillsides at risk for mudslides. Steep hillsides covered with laboratory-made hydrophobic silty and sandy soils were subjected to different rain intensity experiments and environmental exposure.

Status: Completed

Budget: $74,688

Project Partner(s): Caltrans