摘要
长江口的粘性泥沙有89.6%以上来源于长江补给区,一部分来源于废黄河与黄海补给区。长江补给区的粘性泥沙的汇入百分数及其输沙量两者均为已知,据此计算出长江口粘性泥沙沉积量为4.554×10~7t/a,从长江口输向杭州湾与东海补给区的粘性泥沙输沙量为2.247×10~7t/a,废黄河与黄海补给区输向长江口的输沙量为2.730×10~7t/a。长江口粘性泥沙的数量同1915年与1963年实测地形图比较量算的数量为4.469X10^7t/a基本相符。
In the light of regional physiographic characteristics and their effect on clay mineral composition of cohesive sediment (d < 0.005mm), the cohesive sediments in the Changjiang River Estuary are found to come from different source regions, na-mely, the Changjiang River upstream of Jiangyin (CR,x1), the Abandoned Yellow River Delta and northwestern Yellow Sea (AYRDYS, x2), and the Hangzhou Bay and northwestern part of East China Sea (HBECS, x3). The converging region is the Changjing River Estuary (CRE.y). According to the principle of equilibrium of co-hesive sediment load, the equations of clay minerals classification are presented. By means of the least squares method a normal equation for the calculation of conve-rging percentages from all the source regionis geven below.
Where are the coefficients related to
the clay minerals.are the converging percentages.
An evaluation was made according to the samples of clay minerals from each sampling site by using X-ray diffraction method, their types, percentages and the average percentage of clay minerals were determined. Clay mineral perentage is estimated through the evaluation of 72 cohesive sediment samples from 24 sampling sites at the CRE and its source regions. Based on normal equations, the converging percentages of cohesive sediments at the source regions were calculated and given in tab. 6. From Tab. 6 we can see that over 89.6% of cohesive sediments come from the CR.The amount of sediments of the CR at Datong Gauging Station was about 475 million ton./yr. (1953-1984), of which 63.18 million ton./yr. are cohesive sedi-ments. Tab.7 shows the transport of cohesive sedi ments from the AYRDYS to the CRE. The converging percentage of cohesive sediments at the AYRDYS and the amount of cohesive sediments at the CRE are known Dodong Station are known. The amount of cohesive sediments at the CRE is calculated and given in Tab. 8. Tab.8 shows that the amount of cohesive sedimentation at the CRE is 45.54 million ton./yr. of which 23.92 million ton./yr. are cohesive sediments with d < 0.002 mm, which makes up 52.5%. This value agrees quite well with the value of 44.69 million tons per year which is obtained by comparing the topographic maps of the Changjiang River Estuary in 1915 and in 1963. Tab. 8 shows that the cohesive sediments are transported from the CRE into the HDD. The cohesive sediment dischaige is 22.47 million ton/yr. of which 12.66 million ton/yr. are cohesive sediments with d<0.002 mm, it makes up 56.3% of total, and the remaining 9.81 million ton/yr. with 0.005 d >0.002mm makes up 43.7%. The sediments discharge decreases with the increase of grain size.
The cohesive sediment discharge from the AYDH to the CRE is calculated and given in Tab. 9. It shows that cohesive sediment discharge is 27.30 million ton/yr. (from the AYDH to the CRE), of which 16.46 million ton/yr. is cohesive sediments with d<0.002mm, making up 60.3% of the total. The sediment discharge also decreased with the increase of grain size. Norththern Jiangsu coastal current is the main hydraulic factors of cohesive sediment transport.
出处
《地理学报》
EI
CSSCI
CSCD
北大核心
1992年第2期108-112,共5页
Acta Geographica Sinica
基金
国家自然科学基金资助项目
关键词
长江口
海域
泥沙
粘性
数量
输移
Cohesive
sediments Normal equation
Sediment transport
Changjiang River estuary
