Mitigating rainfall induced soil erosion through bio-approach: From laboratory test to field trail

Abstract

Extreme rainfall events exacerbated by global warming can pose great threats to soil stability, causing severe soil erosion and triggering various disasters, such as landslide, debris flow, and land degradation. This study explores the efficacy and critical influence factors of a bio-approach utilizing microbially induced calcite precipitation (MICP) for soil erosion control by conducting a series of laboratory tests. The field trial was also performed to explore the long-term effectiveness of MICP treatment on soil slope under natural rainfall. The laboratory tests results indicate that the peak penetration strength increased 4.43 times, and the soil slaking index and soil loss during rainfall decreased by up to 65.7 % and 92.6 % after MICP treatment. The optimal concentration of cementation solution was found to be 1.0 M. Both the one-phase and two-phase MICP methods proved effective in enhancing soil erosion resistance. However, the two-phase MICP method demonstrated a more pronounced impact on surface soil improvement, while the one-phase MICP method achieved a more uniform treatment effect. The 11-months field erosion trials validated the remarkbale durability of MICP treatment in controlling soil erosion. Additionally, more cycles of MICP treatment further enhanced the soil erosion resistance to rainfall. The bonding and filling effect of MICP-produced CaCO3 precipitates played a crucial role in the improvement of soil water stability and mechnical strength, thereby significantly mitigating soil erosion caused by raindrop and surface runoff during natural rainfall. This study provides valuable suggestions for the pratical application of MICP approch on soil erosion control against increasing extreme rainfall, which is also expected to offer a controllable and sustainable soil improvement solution under the climate change.