10 Nov 2023
 | 10 Nov 2023
Status: this preprint is open for discussion.

Geomorphic indicators of continental-scale landscape transience in the Hengduan Mountains, SE Tibet, China

Katrina D. Gelwick, Sean D. Willett, and Rong Yang

Abstract. Landscapes are sculpted by a complex response of surface processes to external forcings, such as climate and tectonics. Several major river captures have been documented in the Hengduan Mountains, leading to the hypothesis that the region experiences exceptionally high rates of drainage reorganization driven by horizontal shortening and propagating uplift. Here we determine the prevalence, intensity, and spatial patterns of ongoing drainage reorganization in the Hengduan Mountains and evaluate the relative time scales of this transience by comparing drainage divide asymmetry for four geomorphic metrics that operate at different spatial and temporal scales. Specifically, we calculate the migration direction and the divide asymmetry index (DAI) drainage divide asymmetry in catchment-restricted topographic relief (CRR), hillslope gradient (HSG), normalized channel steepness (ksn), and normalized channel distance (χ)ksn and χ are both precipitation-corrected to account for the strong precipitation gradient across the region. The different spatial scales of these geomorphic metrics allow us to establish the relative timescales of observed landscape transience in the Hengduan Mountains, where local scale metrics measure short-term change and integral quantities measure long-term disequilibrium. We find a high incidence of strongly asymmetric divides in all metrics across the Hengduan Mountain region. Although the magnitude of asymmetry varies significantly between metrics, possibly due to a combination of metric-specific thresholds and varying proxy relationships with erosion rate, a majority of divides agree on divide migration direction. Agreement in divide migration direction indicates active landscape response when asymmetry is high and a state of quasi-equilibrium when asymmetry is low. Disagreements between the integral quantity, χ, and the other geomorphic metrics can be explained by different timescales of the underlying geomorphic processes, with χ reflecting a long-term response and CRR, HSG, and ksn capturing short-term perturbations to catchment structure. These perturbations include various transient mechanisms, such as differential tectonic uplift or erodibility, glacial alteration, and river captures. Our work confirms the high incidence of drainage reorganization across the Hengduan Mountains and highlights both transient and stable areas in the landscape with high resolution. We also offer valuable insights on the application of geomorphic metrics that can be generalized and applied to the study of landscape transience and drainage divide asymmetry in other settings.

Katrina D. Gelwick et al.

Status: open (until 22 Dec 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Katrina D. Gelwick et al.

Katrina D. Gelwick et al.


Total article views: 22 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
16 5 1 22 0 0 0
  • HTML: 16
  • PDF: 5
  • XML: 1
  • Total: 22
  • Supplement: 0
  • BibTeX: 0
  • EndNote: 0
Views and downloads (calculated since 10 Nov 2023)
Cumulative views and downloads (calculated since 10 Nov 2023)

Viewed (geographical distribution)

Total article views: 22 (including HTML, PDF, and XML) Thereof 22 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 29 Nov 2023
Short summary
We evaluated the intensity and spatial extent of landscape change in the Hengduan Mountains by identifying areas where river network reorganization is occurring or expected in the future. We combine four metrics that measure topographic imbalances at different spatial and temporal scales. Our study provides a deeper understanding of the dynamic nature of the Hengduan Mountains' landscape and associated drivers, such as tectonic uplift, and insights for applying similar methods elsewhere.