Widespread hillslope gullying on the southeastern Tibetan Plateau: Human or climate-change induced?

Jon Pelletier, Jay Quade, Ron J. Goble, Mark S. Aldenderfer

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11 Citations (Scopus)

Abstract

Many drainage basins adjacent to the upper Tsangpo Valley on the southeastern Tibetan Plateau are pervasively gullied. These gullies expose a stratigraphic record alternating between slow aggradation and stability (i.e., soil development) for much of the Quaternary, suggesting that gullying is recent and unprecedented within at least the past 10-100 k.y. In this paper, we date the initiation of gullying at five sites in the region using optically stimulated luminescence (OSL). We also test alternative hypotheses for gully initiation usingnumerical landform evolution modeling. OSL ages constrain the initiation of gullying to be mid-to-late Holocene in age. This period coincides with the onset of pastoralism in the upper Tsangpo Valley. Numerical modeling suggests that a reduction in vegetation density during the colder, drier conditions of Pleistocene glacial intervals did not trigger gullying because the reduction in vegetation density and hence rates of colluvial deposition in valleys coincided with an unusually dry period less capable of significant fluvial erosion from valleys. As such, low-order valleys most likely did not incise prior to the mid-to-late Holocene because an approximate balance was maintained between colluvial deposition and fluvial erosion. Vegetation changes associated with the onset of pastoralism, however, may have triggered gullying because such changes lowered the rate of colluvial deposition in valleys and/or increased the rate of fluvial erosion in valleys. The results of this paper provide insight into the ways in which drainage basins respond to climatic and anthropogenic perturbations in semiarid climates of moderate relief and underscore the dramatic landscape responses that can occur when geomorphic thresholds are crossed.

Original languageEnglish (US)
Pages (from-to)1926-1938
Number of pages13
JournalBulletin of the Geological Society of America
Volume123
Issue number9-10
DOIs
StatePublished - Sep 2011

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hillslope
plateau
valley
climate change
pastoralism
gully
luminescence
erosion
drainage basin
vegetation
Holocene
landform evolution
aggradation
geological record
modeling
relief
perturbation
Pleistocene
climate
rate

ASJC Scopus subject areas

  • Geology

Cite this

Widespread hillslope gullying on the southeastern Tibetan Plateau : Human or climate-change induced? / Pelletier, Jon; Quade, Jay; Goble, Ron J.; Aldenderfer, Mark S.

In: Bulletin of the Geological Society of America, Vol. 123, No. 9-10, 09.2011, p. 1926-1938.

Research output: Contribution to journalArticle

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