Evaluation of Post-Impact Behavior of Single Droplet on the Hydrophobic Soil Surface: Fid-Bau Portal

Evaluation of Post-Impact Behavior of Single Droplet on the Hydrophobic Soil Surface

Movasat, Mahta / Tomac, Ingrid

Mudflows and debris flow following rainfalls and storms pose a significant threat to people living in the vicinity of hills and mountainous areas. The risk of the extreme event increases near wildfire burned scars due to sand hydrophobicity. Sand particle surface turns hydrophobic due to the high-fire temperatures and organic matter burning, which change sand hydrological characteristics. Water-ponding, decreased infiltration, and increased overflow are some of the consequences of sand hydrophobicity. In this study, a set of single drop tests were conducted on fine, medium, and coarse hydrophobic and regular sand beds on horizontal and tilted surfaces. The results show that hydrophobicity enhances the splashing on the sand surface, regardless of the grain size. In addition, the drop impact on hydrophobic sand triggers particle displacement, and the drop has more mobility on hydrophobic sand. Furthermore, the eroded sand mass fluctuation on hydrophobic sand proves the impact of hydrophobicity on splash erosion and sand erosion. These observations can enhance the understanding of the initiation of debris flow in burned slopes and better understand the behavior of rain droplets following their impact on the sand surface.