# Assessment of Physical Properties of Water Repellent Soils

**Authors:** Mahta Movasat, Ingrid Tomac  
**arXiv:** [2009.09528](https://arxiv.org/abs/2009.09528)  
**Date:** 2020-09-20  
**Summary page:** https://www.summarizepaper.com/en/paper/2009.09528v1/

## Key points

- The study characterizes the physical and mechanical properties of hydrophobic soil collected from Cleveland National Forest in California after the Holy Fire of 2018.
- The research includes comparisons with chemically induced hydrophobic sand in the laboratory to assess their applicability for studying mudflows.
- Hydrophobicity is a particle surface characteristic that governs attraction between water molecules and solid particles, which can be caused by wildfires.
- The study characterizes natural and chemically induced regular and hydrophobic sands by grain size distribution, water retention curve, water contact angle, electron microscopic imaging as well as the relationship between water entry value and drop contact angle in hydrophobic soil.
- Comparative knowledge of natural and chemically induced hydrophobic soil properties will help predict soil behavior and improve insights into post-wildfire soil erosion and mudflow mechanisms.
- This note contributes to a database of wildfire-induced hydrophobic soils with detailed properties that will aid researchers in understanding how wildfires impact soil characteristics over time.

## Summary

This study provides a comprehensive characterization of the physical and mechanical properties of water repellent (hydrophobic) soil collected from Cleveland National Forest in California immediately after the Holy Fire of 2018. The research also includes comparisons with chemically induced hydrophobic sand in the laboratory to assess the applicability of laboratory-made hydrophobic soils for studying mudflows by comparison to natural water-repellent soil collected from the burned site. Hydrophobicity is a particle surface characteristic that governs different levels of attraction between water molecules and solid particles. Wildfires can cause varying degrees of hydrophobicity in shallow soil layers based on fire severity, vegetation type and chemical structure of the soil. The study characterizes natural and chemically induced regular and hydrophobic sands by grain size distribution, water retention curve, water contact angle, electron microscopic imaging as well as the relationship between water entry value and drop contact angle in hydrophobic soil. Comparative knowledge of natural and chemically induced hydrophobic soil properties will help future research better predict soil behavior and improve insights into post-wildfire soil erosion and mudflow mechanisms. This note contributes to a database of wildfire-induced hydrophobic soils with detailed properties that will aid researchers in understanding how wildfires impact soil characteristics over time.