Hydro-geotechnical integration for sustainable mitigation of river-induced landslides along the Batang Ombilin River, West Sumatra

Background The Batang Ombilin River flows through Sawahlunto City and is located adjacent to several provincial roads. The 60° river bend generates hydraulic forces that cause instability and landslides, endangering surrounding roads. Purpose This study integrates hydrological and geotechnical analyses to investigate how river flow dynamics contribute to slope instability and to formulate a sustainable mitigation approach. Methods The research employs a multi-disciplinary approach that integrates geotechnical property data with in-situ hydraulic conditions to dynamically assess slope stability and erosion potential under saturation, delivering a more accurate prediction of failure mechanisms. Slope stability was analyzed using the finite plane method, while erosion potential was investigated using HEC-RAS. Therefore, this study emphasizes a flow- control-based mitigation approach to reduce the energy of erosion. Results Three key strategies are proposed: (1) reducing flow velocity at bends to limit scouring, (2) reinforcing embankments with protective structures as secondary support, slope stability analysis revealed a critical safety factor (SF < 1.2), indicating imminent failure without intervention. Consequently, a cantilever retaining wall with bore pile foundations was designed and proven to be safe, exceeding all required safety criteria against overturning (SF = 3.58 > 2.0) and sliding (SF = 2.06 > 1.5). The addition of bore piles increases the bearing capacity, and 3) flattening the opposite slope while improving the drainage system according to geotechnical conditions. Conclusion The findings confirm that effective control of river flow dynamics is fundamental to ensuring long-term slope stability and reducing landslide risks along the Batang Ombilin corridor. The existence of a verified model to predict slope stability responses to river hydraulic variations provides a crucial basis for planning and designing sustainable geotechnical infrastructure in river valleys worldwide.