Drainage and erosion of Cambodia’s great lake in the middle-late Holocene: the combined role of climatic drying, base-level fall and river capture

Darby, Stephen E.; Langdon, Peter G.; Best, James L.; Leyland, Julian; Hackney, Christopher R.; Marti, Mackenzie; Morgan, Peter R.; Ben, Savuth; Aalto, Rolf; Parsons, Daniel R.; Nicholas, Andrew P.; Leng, Melanie J. ORCID: https://orcid.org/0000-0003-1115-5166. 2020 Drainage and erosion of Cambodia’s great lake in the middle-late Holocene: the combined role of climatic drying, base-level fall and river capture. Quaternary Science Reviews, 236, 106265. 10.1016/j.quascirev.2020.106265

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Official URL: http://dx.doi.org/10.1016/j.quascirev.2020.106265

Abstract/Summary

We provide evidence for a large-scale geomorphic event in Cambodia’s great lake, the Tonlé Sap, during the middle Holocene. The present-day hydrology of the basin is dominated by an annual flood pulse where water from the Mekong River raises the lake level by c. 8 m during the monsoon season. We present new subsurface geophysical data, allied to new and past core studies, which unequivocally show a period of major mid-Holocene erosion across the entire Tonlé Sap basin that is coincident with establishment of the lake’s flood pulse. We argue that this widespread erosion, which removed at least 1.2 m of sediment across the lake’s extent, was triggered by up to three, likely interacting, processes: (1) base-level lowering due to mid-Holocene sea-level fall, leading to (2) capture of the Tonlé Sap drainage by the Mekong River, and (3) a drying climate that also reduced lake level. Longer-term landscape evolution was thus punctuated by a rapid, river capture- and base-level fall- induced, lake drainage that established the ecosystem that flourishes today. The scale of change induced by this mid-Holocene river capture event demonstrates the susceptibility of the Tonlé Sap lake to ongoing changes in local base-level and hydrology induced by anthropogenic activity, such as damming and sand mining, within the Mekong River Basin.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.quascirev.2020.106265
ISSN:	02773791
Date made live:	24 Jul 2020 15:24 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/528226

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.quascirev.2020.106265

ISSN:

02773791

Date made live:

24 Jul 2020 15:24 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/528226