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| Titel |
Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities |
| VerfasserIn |
J. H. Gao, J. Jia, Y. P. Wang, Y. Yang, J. Li, F. Bai, X. Zou, S. Gao |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 2 ; Nr. 19, no. 2 (2015-02-02), S.645-655 |
| Datensatznummer |
250120614
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| Publikation (Nr.) |
 copernicus.org/hess-19-645-2015.pdf |
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| Zusammenfassung |
| In order to evaluate the impact of human activities (mainly dam
building) on the Changjiang River sediment discharging into the sea, the
spatial–temporal variations in the sediment load of different tributaries of
the river were analyzed to reveal the quantity, grain size and composition
patterns of the sediment entering the sea. The results show that the timing
of reduction in the sediment load of the main stream of the Changjiang was
different from those associated with downstream and upstream sections,
indicating the influences of the sub-catchments. Four stepwise reduction
periods were identified, i.e., 1956–1969, 1970–1985, 1986–2002, and
2003–2010. The proportion of the sediment load originating from the Jinsha
River continuously increased before 2003; after 2003, channel erosion in the
main stream provided a major source of the sediment discharging into the
sea. In addition, in response to dam construction, although mean grain size
of the suspended sediment entering the sea did not change greatly with these
different periods, the inter-annual variability for sediment composition or
the relative contributions from the various tributaries changed
considerably. Before 2003, the clay, silt and sand fractions of the river
load were supplied directly by the upstream parts of the Changjiang; after
2003, although the clay component may still be originating mainly from the
upstream areas, the source of the silt and sand components have been shifted
to a large extent to the river bed erosion of the middle reach of the river.
These observations imply that the load, grain size and sediment composition
deposited over the coastal and shelf water adjacent to the river mouth may
have changed rapidly recently, in response to the catchment changes. |
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