Proglacial river sediment fluxes in the south-eastern Tibetan Plateau:
Ming Yong Glacier in the Upper Mekong River
Abstract
Glacial and proglacial erosion are important sediment sources in a river
basin. The retreat of many glaciers on the Tibetan Plateau has important
implications on the supply of fresh water and sediment dynamics for
downstream river basins. Despite the importance of water and sediment
dynamics at these catchments, existing quantification of suspended
sediment fluxes from glacial catchments on the Tibetan Plateau is
limited due to poor accessibility and challenging environments. This
study presents the results of in-situ investigations of water discharge
and suspended sediment fluxes from the Ming Yong glacial catchment in
Yunnan, Southwest China, between August 2013 and July 2017. The results
show that the variation in water discharge and suspended sediment was
highly seasonal. The variation of average suspended sediment
concentration was large – 69±45 mg/L; 119±104 mg/L; 94±97 mg/L in 2013,
2015, 2016, respectively. We estimate that the sediment yield from Ming
Yong catchment was highly variable ranging from 1104 t/km
2/year in 2013to 2281 t/ km 2/year
in 2016, with 65-78% of the total annual sediment load occurring during
summer (June to August). These annual variations in the sediment yield
can be attributed largely to precipitation patterns, or otherwise,
extreme melting events. This study has provided a benchmark dataset that
can be used for further works that investigate the impact of climate
change on sediment dynamics in glacierized catchments in the Tibetan
Plateau. Subsequently, the study let us better understand the increasing
sediment supply to the Upper Mekong River from glacierized catchments.