GEOGRAPHICAL RESEARCH ›› 1993, Vol. 12 ›› Issue (2): 9-18.doi: 10.11821/yj1993020002

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THE STUDIES ON SEDIMENT TRANSPORT MODE AND ITS APPLICATION IN THE OUJIANG RIVER ESTUARY

Zhu Yongkang, Sun Zhilin   

  1. Hangzhou University
  • Received:1991-04-04 Revised:1993-01-31 Online:1993-06-15 Published:1993-06-15

Abstract: In view of the general character of several mountainous macrotidal estuaries in the provinces of Zhejiang and Fujian,the authors try to probe both the universal law of sediment transport and,the control means in estuaries of this kind by the monographic research on the Oujiang River estuary.The methods for geography and river mechanics as well as s'edimen-tology are applied to the detailed analysis of sedimentation in the estuary on three aspects.(1) a relation between the formation of an estuary and the sediment transport.(2) sediment from the river basin and its transport modes.(3) sediment from the adjacent coastal waters and its characteristics of transport by the tidal current.The basic conclusions are as follows.1.The coarse sediment grains larger than 0.1 mm ill size are widely distributed in the estuarine channel,among which the gravel particles move downstream by way of bed load and deposit in the upper estuary while the sand particles,except some inlaid in the gravel deposits as well as a small amount moved as bed load and tongued eastward in the Wenzhou Bay,are largely transported in such ways as either rolling and saltation or suspension into the lower estuary during flood season.In dry season the sand particles move there and back as bed load by the tidal current in the main channel.2.According to quantitative analysis on the measured data,the amount of coarse sediments from the Oujiang River basin every year,approxmiately 780 000 tons is much less than that of erosion and deposition in the estuary,several millions of tons.This shows that the movement of sand particles on local estuarine bed is the main causes for erosion and deposition of the estuary,and thus should be considered emphatically in the estuarine regulation.3.Transported in suspension,the fine sediment grains less than 0.1mm in size are mostly derived from the adjacent coastal waters besides a little from the Oujiang River.An obvious feature of suspended sediment transport is the presence of a turbidity maximum which migrates to and from with the tidal current.The maximum distance of shift is about 18 km.4.Because the coarse sediment differs fro the fine in the laws for transportation and deposition,it is suggested that the different control principles of both sediments should be adopted for the estuarine regulation

Key words: estuary, sediment transport modes, tidal flow transport, Oujiang River