Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities
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...
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doaj-cd539559c74d4adeae1d014c9dd6fe542020-11-24T22:40:45ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382015-02-0119264565510.5194/hess-19-645-2015Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activitiesJ. H. Gao0J. Jia1Y. P. Wang2Y. Yang3J. Li4F. Bai5X. Zou6S. Gao7Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, ChinaState Research Centre for Island Exploitation and Management, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, ChinaMinistry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, ChinaMinistry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, ChinaQingdao Institute of Marine Geology, Qingdao 266071, ChinaQingdao Institute of Marine Geology, Qingdao 266071, ChinaMinistry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, ChinaMinistry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, ChinaIn 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.http://www.hydrol-earth-syst-sci.net/19/645/2015/hess-19-645-2015.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
J. H. Gao J. Jia Y. P. Wang Y. Yang J. Li F. Bai X. Zou S. Gao |
spellingShingle |
J. H. Gao J. Jia Y. P. Wang Y. Yang J. Li F. Bai X. Zou S. Gao Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities Hydrology and Earth System Sciences |
author_facet |
J. H. Gao J. Jia Y. P. Wang Y. Yang J. Li F. Bai X. Zou S. Gao |
author_sort |
J. H. Gao |
title |
Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities |
title_short |
Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities |
title_full |
Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities |
title_fullStr |
Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities |
title_full_unstemmed |
Variations in quantity, composition and grain size of Changjiang sediment discharging into the sea in response to human activities |
title_sort |
variations in quantity, composition and grain size of changjiang sediment discharging into the sea in response to human activities |
publisher |
Copernicus Publications |
series |
Hydrology and Earth System Sciences |
issn |
1027-5606 1607-7938 |
publishDate |
2015-02-01 |
description |
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. |
url |
http://www.hydrol-earth-syst-sci.net/19/645/2015/hess-19-645-2015.pdf |
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