Tectonic Stress Control on River Incision and Drainage Divide Migration in the Diancang Mountains, SE Tibetan Plateau

How tectonic stress influences topographic evolution remains a central question in regions of active mountain building. The Diancang Mountains, located at the southeastern margin of the Tibetan Plateau, are characterized by steep topography, active fault systems, and highly dynamic river networks, making them an ideal natural laboratory for studying the coupling between tectonic activity and landscape evolution.We specifically investigate how major strike-slip faults locally perturb the regional stress field to govern uplift distribution, which, in concert with fluvial erosion, drives the topographic evolution of the Diancang Mountains.

To address this, we integrate three-dimensional near-surface stress modeling with standard topographic metrics derived from DEM-based terrain analysis. Using Abaqus, we simulate near-surface stress fields by applying boundary conditions consistent with regional tectonic stress field, explicitly accounting for major fault geometries and surface topography.

Preliminary results reveal a strong spatial correlation between zones of elevated differential stress and enhanced river incision. Specifically, we observe persistently high channel steepness (k_sn) along river segments associated with major fault zones and localized stress concentrations. Furthermore, c-mapping identifies pronounced asymmetric drainage divides (interpreted as across divide gradients in erosion rate) in regions of high stress gradients. The orientations of principal stress axes derived from our numerical models align with the preferred directions of divide migration inferred from c analysis.

These results demonstrate that the present-day fluvial morphology of the Diancang Mountains primarily reflects the influence of the shallow crustal stress field that is locally perturbed by major strike slip faulting. Our approach combining finite element stress modeling with quantitative morphometry provides a viable methodological framework for linking tectonic stress patterns to landscape evolution in active mountain ranges.