Sediment Routing and Anthropogenic Impact in the Huanghe River Catchment, China: An Investigation Using Nd Isotopes of River Sediments
The Huanghe once had a sediment flux of >1,000 Mt/yr, but this has decreased by ∼90% as its river sediment routing systems have undergone dramatic changes influenced by human activities such as dam construction. However, the way in which the sediment geochemistry of the river has responded to the...
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| Published in: | Water resources research 2021-09, Vol.57 (9), p.n/a |
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| Main Authors: | , , , , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The Huanghe once had a sediment flux of >1,000 Mt/yr, but this has decreased by ∼90% as its river sediment routing systems have undergone dramatic changes influenced by human activities such as dam construction. However, the way in which the sediment geochemistry of the river has responded to the altered sediment routing processes is not well known. This study investigates the sediment source‐to‐sink routing regime of the Huanghe River using Nd isotope fingerprinting. Four major source terranes, namely the Songpan‐Ganzi (SG) Block, Ordos Desert (OD), Chinese Loess Plateau (CLP) and North China Craton (NCC) are recognized according to their distinct Nd isotopes. The gradual downstream decrease in εNd values in sediments of the upper Huanghe indicates a decreasing contribution of material from the SG Block and a corresponding increase contribution of local underlying basement rocks, which is inferred to be related to sediment capture by a cascade of hydroelectric dams. A gradual increase in εNd from Yinchuan to Tongguan suggests an increasing contribution from the CLP under intense erosion. Relatively low εNd in the downstream sediments suggest a contribution from proximal NCC basement, consistent with the shift from deposition to erosion in the lower channel in recent years. The marked heterogeneity in Nd isotopes in the Huanghe sediments corresponds well to sediment source‐to‐sink processes in response to increasing human impacts. In a setting of global rivers facing strong anthropogenic impacts, the ways in which altered sediment routing systems affect river sediment geochemistry deserve more research attention.
Plain Language Summary
The sediment flux of the Huanghe River (Yellow River) once exceeded 1,000 Mt/yr, but has decreased by ∼90% over the past 60 years owing mainly to the nature and intensity of human activity, during which river sediment transport processes have also changed. Here, we present Nd isotopic data for sediments from the Huanghe mainstream to investigate sediment provenances and the river sediment routing system under anthropogenic influences. Nd isotopes of potential source terrane materials allow the sediment provenances to be discriminated. The construction of cascade hydroelectric engineering projects in the upper reaches might have caused a marked decrease in sediment contribution from the Songpan–Ganzi Block, as evidenced from the gradual downstream decrease in sediment εNd in the upper reaches. The gradual increase in εNd valu |
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| ISSN: | 0043-1397 1944-7973 |