Construction-induced groundwater changes and hillslope instability

The paper explores how urban construction activities on steep slopes in hilly or mountainous regions, where land scarcity drives development, exacerbate landslide risks. Landslides frequently occur near construction sites, yet these human influences are often excluded from landslide mechanism analyses. The study posits that such events are not coincidental but result from construction-driven disruptions to hillslope hydrogeology and groundwater systems. Activities such as coastal land reclamation, excavations and deep foundation works significantly alter subsurface water flow, raising groundwater levels, a critical yet underappreciated factor in slope stability assessments. Through case studies in Hong Kong, the paper demonstrates how construction modifies hydrogeological conditions in slopes with confined groundwater, typically found in igneous rock formations. These slopes feature permeable fracture zones between shallow, weathered, clay-rich soil layers and deeper bedrock. Construction activities disrupt these systems, destabilizing slopes by increasing porewater pressure. For instance, excavations can intercept aquifers, and deep foundations may obstruct natural drainage, both elevating landslide susceptibility. The findings stress the need to integrate human-induced hydrogeological changes into slope stability evaluations and urban planning. This approach emphasizes proactive consideration of construction impacts on subsurface water regimes and is critical for mitigating landslide risks in densely populated mountainous regions.