Bedload-to-suspended load ratio and rapid bedrock incision from Himalayan landslide-dam lake record

Beth Pratt-Sitaula; Michelle Garde; Douglas W. Burbank; Michael Oskin; Arjun Heimsath; Emmanuel Gabet

doi:10.1016/j.yqres.2007.03.005

Bedload-to-suspended load ratio and rapid bedrock incision from Himalayan landslide-dam lake record

Beth Pratt-Sitaula, Michelle Garde, Douglas W. Burbank, Michael Oskin, Arjun Heimsath, Emmanuel Gabet

Research output: Contribution to journal › Article › peer-review

81 Scopus citations

Abstract

About 5400 cal yr BP, a large landslide formed a > 400-m-tall dam in the upper Marsyandi River, central Nepal. The resulting lacustrine and deltaic deposits stretched > 7 km upstream, reaching a thickness of 120 m. ¹⁴C dating of 7 wood fragments reveals that the aggradation and subsequent incision occurred remarkably quickly (∼ 500 yr). Reconstructed volumes of lacustrine (∼ 0.16 km³) and deltaic (∼ 0.09 km³) deposits indicate a bedload-to-suspended load ratio of 1:2, considerably higher than the ≤ 1:10 that is commonly assumed. At the downstream end of the landslide dam, the river incised a new channel through ≥ 70 m of Greater Himalayan gneiss, requiring a minimum bedrock incision rate of 13 mm/yr over last 5400 yr. The majority of incision presumably occurred over a fraction of this time, suggesting much higher rates. The high bedload ratio from such an energetic mountain river is a particularly significant addition to our knowledge of sediment flux in orogenic environments.

Original language	English (US)
Pages (from-to)	111-120
Number of pages	10
Journal	Quaternary Research
Volume	68
Issue number	1
DOIs	https://doi.org/10.1016/j.yqres.2007.03.005
State	Published - Jul 2007
Externally published	Yes

Keywords

Bedload
Bedrock incision
Himalaya
Landslide dam
Nepal
Suspended load

ASJC Scopus subject areas

Arts and Humanities (miscellaneous)
Earth-Surface Processes
Earth and Planetary Sciences(all)

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10.1016/j.yqres.2007.03.005

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title = "Bedload-to-suspended load ratio and rapid bedrock incision from Himalayan landslide-dam lake record",

abstract = "About 5400 cal yr BP, a large landslide formed a > 400-m-tall dam in the upper Marsyandi River, central Nepal. The resulting lacustrine and deltaic deposits stretched > 7 km upstream, reaching a thickness of 120 m. 14C dating of 7 wood fragments reveals that the aggradation and subsequent incision occurred remarkably quickly (∼ 500 yr). Reconstructed volumes of lacustrine (∼ 0.16 km3) and deltaic (∼ 0.09 km3) deposits indicate a bedload-to-suspended load ratio of 1:2, considerably higher than the ≤ 1:10 that is commonly assumed. At the downstream end of the landslide dam, the river incised a new channel through ≥ 70 m of Greater Himalayan gneiss, requiring a minimum bedrock incision rate of 13 mm/yr over last 5400 yr. The majority of incision presumably occurred over a fraction of this time, suggesting much higher rates. The high bedload ratio from such an energetic mountain river is a particularly significant addition to our knowledge of sediment flux in orogenic environments.",

keywords = "Bedload, Bedrock incision, Himalaya, Landslide dam, Nepal, Suspended load",

author = "Beth Pratt-Sitaula and Michelle Garde and Burbank, {Douglas W.} and Michael Oskin and Arjun Heimsath and Emmanuel Gabet",

note = "Funding Information: Bir B. Tamang, Mukesh Ojha, Himalayan Experience, and the Nepali Department of Hydrology and Meteorology provided invaluable support in the field. Thanks to M. Attal for helpful comments and access to unpublished data, T. Dunne for discussions, and R. Anderson for an unpublished 14 C date. Reviews by J. Quade, C. France-Lanord, and D. Montgomery greatly improved the quality of the manuscript. This project was supported by NSF Continental Dynamics Program (EAR 9909647) and the NSF REU program.",

year = "2007",

month = jul,

doi = "10.1016/j.yqres.2007.03.005",

language = "English (US)",

volume = "68",

pages = "111--120",

journal = "Quaternary Research",

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TY - JOUR

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AU - Pratt-Sitaula, Beth

AU - Garde, Michelle

AU - Burbank, Douglas W.

AU - Oskin, Michael

AU - Heimsath, Arjun

AU - Gabet, Emmanuel

N1 - Funding Information: Bir B. Tamang, Mukesh Ojha, Himalayan Experience, and the Nepali Department of Hydrology and Meteorology provided invaluable support in the field. Thanks to M. Attal for helpful comments and access to unpublished data, T. Dunne for discussions, and R. Anderson for an unpublished 14 C date. Reviews by J. Quade, C. France-Lanord, and D. Montgomery greatly improved the quality of the manuscript. This project was supported by NSF Continental Dynamics Program (EAR 9909647) and the NSF REU program.

PY - 2007/7

Y1 - 2007/7

N2 - About 5400 cal yr BP, a large landslide formed a > 400-m-tall dam in the upper Marsyandi River, central Nepal. The resulting lacustrine and deltaic deposits stretched > 7 km upstream, reaching a thickness of 120 m. 14C dating of 7 wood fragments reveals that the aggradation and subsequent incision occurred remarkably quickly (∼ 500 yr). Reconstructed volumes of lacustrine (∼ 0.16 km3) and deltaic (∼ 0.09 km3) deposits indicate a bedload-to-suspended load ratio of 1:2, considerably higher than the ≤ 1:10 that is commonly assumed. At the downstream end of the landslide dam, the river incised a new channel through ≥ 70 m of Greater Himalayan gneiss, requiring a minimum bedrock incision rate of 13 mm/yr over last 5400 yr. The majority of incision presumably occurred over a fraction of this time, suggesting much higher rates. The high bedload ratio from such an energetic mountain river is a particularly significant addition to our knowledge of sediment flux in orogenic environments.

AB - About 5400 cal yr BP, a large landslide formed a > 400-m-tall dam in the upper Marsyandi River, central Nepal. The resulting lacustrine and deltaic deposits stretched > 7 km upstream, reaching a thickness of 120 m. 14C dating of 7 wood fragments reveals that the aggradation and subsequent incision occurred remarkably quickly (∼ 500 yr). Reconstructed volumes of lacustrine (∼ 0.16 km3) and deltaic (∼ 0.09 km3) deposits indicate a bedload-to-suspended load ratio of 1:2, considerably higher than the ≤ 1:10 that is commonly assumed. At the downstream end of the landslide dam, the river incised a new channel through ≥ 70 m of Greater Himalayan gneiss, requiring a minimum bedrock incision rate of 13 mm/yr over last 5400 yr. The majority of incision presumably occurred over a fraction of this time, suggesting much higher rates. The high bedload ratio from such an energetic mountain river is a particularly significant addition to our knowledge of sediment flux in orogenic environments.

KW - Bedload

KW - Bedrock incision

KW - Himalaya

KW - Landslide dam

KW - Nepal

KW - Suspended load

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ER -

Bedload-to-suspended load ratio and rapid bedrock incision from Himalayan landslide-dam lake record

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Keywords

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