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UW- Surface Process Group

Explore diverse erosion rates and patterns across the Himalayan region over various timescales, from fluvial incision models to geochemical mass balance studies. Discover the impact of rapid erosion in key locations and the influence of catastrophic floods on landscape evolution.

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UW- Surface Process Group

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  1. UW- Surface Process Group • Alison Anders (TRMM-model precipitation) • Noah Finnegan (fluvial incision, cosmogenics) • Birgit Hagedorn (geochemical mass balance) • Bernard Hallet (overview) • Amanda Henck (landslides, erosion rates) • Bretwood Higman (modeling topo., susp. seds) • Dave Montgomery (overview) • Matt Kuharic (cosmogenics) • Dick Stewart (detrital zircons and apatite) • J. Stone, A. Gillespie, B. Nelson, J. Bardeen

  2. Tibet and Himalaya from Eastnote: range is narrow

  3. Central Theme: Erosion Rates • Spatial patterns over a range of time scales • Time scales ranging from102 to 106 years • Current • Theoretical (fluvial incision model) • Mass Balance (based on diverse geochemical data)

  4. Theoretical studies • Fluvial incision rate index (scales w/ river power) show clearly that rapid erosion is currently confined to the Tsangpo Gorge, including the lower Po-Tsangpo • Knickpoint dynamics (statics) mark active tectonic aneurysms not only at syntaxes but all along Himalaya • Regional GIS study: relief, high low-relief surfaces, topographic trends • Regional precipitation study (Alison, TRMM measurements) • Simulations of drainage development with spatially varying uplift (Hig)

  5. TRMM Precipitation Data 4-year compilation A. Anders

  6. Mass Balance Geochemical (dissolved load + suspended load + bedload = bedrock, following Galy and France-Lanord) • i. major ions • ii. minor and trace ions Zircons (zircons from rapidly eroding area make up nearly half of zircons in upper Brahmaputra) Trace minerals (garnet)

  7. Sampling locations 95° 00 96° 00 1 Tungmai PARLONG Dongjiu 2 30° 00 Po Tsangpo Loulan Namsche Barwa 7782 m NUXIANG 29° 30 Jiali-Parlung Tsangpo Siang Yarlung Tsangpo Medog Pasighat Yarlung Tsangpo Brahamaputra Year round sampling sites Sampling location

  8. 2 1 3 • Sampling in Nuxiang • Installation of rain gauge in Tong Mai • Sampling in Parlong

  9. 102 to 104 year time scales • 102 to 103 year time scale, cosmogenic radionuclides • bedrock (strath) terraces provide a measure of incision rates • sediments reflect basin-average exposure time (time scale: penetration depth/erosion rate, O(1m/0.001m/yr= 1000yrs) • 103 to 104 yrs • Catastrophic floods may be responsible for much of the erosion • Chronology and frequency of floods are closely tied to chronology of glaciations

  10. 105 to 106 yrs time scale from sands • .Zircon fission track ages (locking in T ~ 240 to 300C) in sands from river above and below rapidly eroding areas • Detrital apatite fission track ages (locking in T ~ 110C)

  11. Brahmaputra (Siang), Pasighat

  12. Vast Sea of Sands, NE India

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