Landslides, River Incision, and Relationships among Topography and Erosion on the Eastern Margin of the Tibetan Plateau SESE logo

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Project Summary

Personnel:  Will Ouimet (Ph.D.)  Leigh Royden (Ph.D.)  Kip Hodges (Ph.D.)

Using low-temperature thermochronology we have focused on trying to better constrain the initiation of major river incision along the eastern margin by analyzing three age-elevation transects, one collected in the Dadu river gorge, one in the Yalong, and the final one in the Yangtze. Previous interpretations published in Geology (Clark et al., 2005, “Late Cenozoic uplift of southeastern Tibet”) identified a two-step erosion history of accelerated incision into slowly eroding, relict landscape. However, none of Clark et al.'s transects captured the onset of accelerated incision. New data confirms the acceleration of erosion at ~10 Ma in a single transect within the Dadu River gorge. Data from the Yalong and Yangtze River gorges indicate the same long-term exhumation rates (0.3-0.4 mm/yr) as the Dadu, but slightly different timing for the onset of major river incision. 

Our landscape evolution studies have focused on the processes, rates and forms of erosion and river incision in Eastern Tibet. We use an integration of remote sensing and digital analysis of topographic data and satellite imagery along with geomorphic observations and measurements from field work, together with cosmogenic and luminescence dating techniques. We recently completed the systematic measurement of short-term (102-105 yr) erosion rates at the basin scale throughout the eastern margin of the Tibetan Plateau. We use these data to: (1) complement long-term rates (i.e., from low-temperature thermochronology); (2) characterize the transient morphology of the eastern Tibet landscape; and (3) address fundamental relationships between erosion and topography. 

We have also studied how landslides exert control on river profile form in eastern Tibet. Large landslides are a prominent feature of hillslope erosion in steep, actively incising landscapes, yet few models of bedrock river incision and landscape evolution allow for dynamic feedbacks between river incision and the influence of large landslides. Examples from the eastern margin of the Tibetan plateau highlight the interaction between landslide dams, channel morphology, longitudinal river profiles, and river incision. We use these examples to motivate and formulate a simple, probabilistic, numerical model which provides a quantitative framework for evaluating how landslides influence long-term river incision and landscapes in general.

Mars:
Athabasca Valles
Tibet: Topography
& Erosion
Nepal: Active
Thrust Systems
New Zealand:
Knickpoint Migration
Relief Evolution:
Active Tectonics 
Relief Evolution:
Fluvial to Glacial 
King Range, CA:
Channel Response
 
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