Interaction of landslide spatial patterns and river canyon landforms: Insights into the Three Parallel Rivers Area, southeastern Tibetan Plateau

The interaction and mechanism of landslide spatial patterns and river canyon landforms are significant for understanding geomorphic evolution in intensive tectonic alpine environments. This study focuses on the Three Parallel Rivers Area (TPRA) in the southeastern Tibetan Plateau encompassing three parallel rivers (the Nujiang, Lancang, and Jinsha Rivers), to examine the synergistic evolution of geomorphic features and landslides. The analysis revealed a pattern of landslide aggregation in the river valley characterized by the sequence Nujiang > Lancang > Jinsha Rivers. This pattern aligns closely with the distribution of geomorphic indices (local relief, surface erosion index, and threshold slope gradient) in the valleys. As local relief, normalized surface erosion index and normalized threshold slope gradient increase, the mean values of normalized landslide area density (NLAD) rise from around 0.11 to 0.39, 0.16 to 0.48, and 0.10 to 0.21, respectively. Concurrently, the mean values of normalized frequency of landslide dams (NFLD) increase from around 0.05 to 0.24, 0.12 to 0.22, and 0.02 to 0.17, respectively. Additionally, knickpoints could induce upstream suppression and downstream promotion of landslides showcasing the feedback of landslides on the valley landscape. Our findings indicate that the landform formation process in the southeastern Tibetan Plateau orogen is intricately linked to a substantial landsliding response and the observed mass movements vividly mirror the landform formation pattern. These results hold potential implications for understanding the dynamic equilibrium between uplift and surface erosion in the region. This study enhances our understanding of the interaction and mechanisms of landslides and valley landforms.