Mechanism of the coevolution of landslides and river valleys in the Three Gorges Reservoir area

<p indent="0mm">The Three Gorges Reservoir Area (TGRA) of the Yangtze River in China is a region of profound geological significance and human habitation; however, it is also highly susceptible to landslides because of its dynamic geological and climatic conditions. The area’s propensity for landslides is not due only to natural conditions but is a complex interplay of various factors, including tectonic activity, climate change, and human influence. The aim of this study is to examine these factors and provide a comprehensive understanding of landslide formation in the TGRA, which is crucial for the safety and sustainable development of the region. The geological and climatic context of the TGRA is a long history of tectonic uplift, which, coupled with climatic variability, has shaped the unique geomorphology of the area. The incision of the Yangtze River and the development of its valleys have resulted in steep slopes and weak geological formations, making the area prone to slope instability. The initial phase of this study involves synthesizing this geological and climatic background to lay the groundwork for understanding landslide phenomena. This research employs a statistical analysis of landslide distribution, revealing that the occurrence of landslides is not random but is instead closely related to specific elevations, particularly those corresponding to ancient river terraces. This finding suggests that the evolution of the valleys and the occurrence of landslides are interconnected, with certain phases of valley development and climatic shifts increasing the susceptibility of the region to slope failure. A significant contribution of this study is the establishment of a coevolutionary framework between landslides and valley development. These findings demonstrate that multistage river incision and cyclic climatic transitions, such as glacial-interglacial periods, have led to the formation of stacked river terraces and slope structures that are prone to large-scale slope failure. The mechanism of “terrace-slope coupling” explains the spatial distribution of landslides and their recurrence. Moreover, in this research, how contemporary climate change exacerbates these geological risks is investigated. The increased rainfall intensity and fluctuating water levels in reservoirs reactivate ancient landslide structures, whereas human activities, such as urbanization on marginal slopes, further increase the vulnerability of the region. By examining representative landslides, in this study, their evolutionary modes are categorized into three types, which have significant implications for disaster mitigation strategies. The findings of this study have far-reaching implications for disaster prevention and risk management in the TGRA. This study advances the theoretical understanding of landslide genesis in active tectonic settings and under the influence of climate change. This research provides actionable guidelines for land-use planning, the development of early warning systems, and engineering interventions to mitigate landslide risk. By integrating geohistorical analysis with contemporary risk management, via this study, a model that can be replicated in other major river basins worldwide is proposed. Ultimately, this study’s contributions are not confined to academic circles but have tangible benefits for the safety of the 20 million residents and the longevity of critical infrastructure in the Yangtze River Economic Belt. By understanding the complex interplay of geological and climatic factors that lead to landslides, the findings of this study equip policy-makers and engineers with the knowledge needed to implement effective measures to protect lives and property. The comprehensive approach taken in this research sets a precedent for future studies on landslide hazards and risk management, ensuring that the lessons learned from the TGRA can be applied to other regions facing similar challenges.