Klemme, Alexandra, Warneke, Thorsten, Bovensmann, Heinrich, Weigelt, Matthias, Müller, Jürgen, Rixen, Tim ORCID: https://orcid.org/0000-0001-8376-891X, Notholt, Justus and Lämmerzahl, Claus (2024) Sediment transport in South Asian rivers high enough to impact satellite gravimetry. Hydrology and Earth System Sciences, 28 (7). pp. 1527-1538. DOI https://doi.org/10.5194/hess-28-1527-2024.

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Satellite gravimetry is used to study the global hydrological cycle. It is a key component in the investigation of groundwater depletion on the Indian subcontinent. Terrestrial mass loss caused by river sediment transport is assumed to be below the detection limit in current gravimetric satellites of the Gravity Recovery and Climate Experiment Follow-On mission. Thus, it is not considered in the calculation of terrestrial water storage (TWS) from such satellite data. However, the Ganges and Brahmaputra rivers, which drain the Indian subcontinent, constitute one of the world's most sediment-rich river systems. In this study, we estimate the impact of sediment mass loss within their catchments on local trends in gravity and consequential estimates of TWS trends. We find that for the Ganges–Brahmaputra–Meghna catchment sediment transport accounts for (4 ± 2) % of the gravity decrease currently attributed to groundwater depletion. The sediment is mainly eroded from the Himalayas, where correction for sediment mass loss reduces the decrease in TWS by 0.22 cm of equivalent water height per year (14 %). However, sediment mass loss in the Brahmaputra catchment is more than twice that in the Ganges catchment, and sediment is mainly eroded from mountain regions. Thus, the impact on gravimetric TWS trends within the Indo–Gangetic Plain – the main region identified for groundwater depletion – is found to be comparatively small (< 2 %).

Document Type: Article
Programme Area: PA2
Research affiliation: Biogeochemistry and Geology > Carbon and Nutrient Cycling
Refereed: Yes
Open Access Journal?: Yes
DOI: https://doi.org/10.5194/hess-28-1527-2024
ISSN: 1607-7938
Date Deposited: 04 Jul 2024 10:49
Last Modified: 04 Jul 2024 10:49
URI: http://cris.leibniz-zmt.de/id/eprint/5453

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