Development of a Laboratory-Scale Model to Evaluate Rainfall-Induced Surface Erosion Mitigation in MICP- Treated Sand

Abstract

Microbially Induced Calcite Precipitation (MICP) has conventionally relied on Sporosarcina pasteurii for soil improvement, yet the potential of other urease-producing bacterial strains to enhance surface erosion remains largely unexplored, especially under field-simulated rainfall conditions. This study investigates the erosion behaviour and durability of Ganga River Sand (GRS) surfaces treated with three alternative ureolytic bacteria—Bacillus sp., Bacillus sphaericus, and Bacillus subtilis. Laboratory-scale GRS surfaces were prepared at 70% relative density and treated with a CaCl₂–urea bio-cementation solution, followed by microstructural characterization and controlled rainfall simulations replicating natural rainwater chemistry and realistic intensities. To evaluate long-term stability, additional tests were conducted using simulated acidic rainfall at a 45° slope to represent harsh weathering conditions typical of vulnerable geomorphic environments. Key parameters, including physicochemical changes, erosion rate, erosion patterns, and post-erosion surface strength, were systematically monitored. The results provide comparative insights into the performance of these bacterial strains in mitigating rainfall-induced surface erosion and demonstrate the potential of optimized MICP treatments for enhancing the resilience of sandy slopes under both natural and adverse environmental conditions.