A typical transect of the riparian zone along the Yangtze mainstream of the middle Three Gorges Reservoir is selected to determine the lateral distribution of sedimentation rates against elevation, and to explore the effect of the reservoir water level regulation and the seasonal variation of suspended sediment concentrations of the Upper Yangtze River. It is found that the net sedimentation mainly takes place within the portions between 145-168 m. The cumulative net sediment depth ranges from 1.1-39.9 cm during the 2010 survey and it decreases with the increase of the elevation. The average sediment depth is 14.9 cm between the elevations of 145-155 m, and 2.6 cm in the portions above. The sediment depth ranges from 3-80cm during the 2013 field survey, indicating the severity of the sediment accretion during the initial period of dam operation. The riparian sediments become coarser with the increase of the elevation, which indicates that the sandy fraction of the bulk sediment increases at a higher elevation. The sediment grain-size composition at lower elevations is close to that of the suspended sediment, while that at a higher elevation is coarser than the suspended sediment. The sedimentation in the riparian zone is closely related to the water level regulation induced by the regular dam operation. During a wet season when the reservoir water level is low, a high fluvial suspended sediment yield leads to a significant sedimentation in the lower portions of the riparian zone. During the dry season when the fluvial suspended sediment supply is limited, much fewer sedimentation occurs at the upper portions. Relatively longer inundation duration also contributes to a higher sediment depth in the lower portions of the riparian zone. It can thus be concluded that the sediment in the lower portions of the riparian zone is due to the fluvial suspended sediment yield during the wet season, while the sediment in the upper portions of the riparian zone originates from the bank erosion.
TANG Qiang
,
HE Xiubin
,
BAO Yuhai
,
ZHONG Ronghua
,
YAN Dandan
,
GAO Jinzhang
. Sedimentation Processes in a Typical Riparian Zone Along the Yangtze Mainstream of the Three Gorges Reservoir[J]. Science & Technology Review, 2014
, 32(24)
: 73
-77
.
DOI: 10.3981/j.issn.1000-7857.2014.24.012
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