长江口最大浑浊带悬沙浓度变化趋势及成因

doi:10.11821/dlxb201309007

摘要/Abstract

摘要： 基于长江河口1959-2011 年实测悬沙浓度数据,通过对河口最大浑浊带外围海域泥沙要素分析的基础上,研究了近期流域人类活动和河口整治工程对最大浑浊带悬沙浓度的影响。研究表明:① 流域人类活动对入海水量影响较小,无明显趋势变化,而沙量和含沙量呈现锐减趋势,也使得进入河口区域的泥沙量呈现一致锐减;② 长江口外海域和南部杭州湾海域悬沙浓度变化不大,北部苏北沿岸略有减小,因数值较长江口海滨区小约1 个数量级,对浑浊带影响较小;③ 最大浑浊带位置受径流和潮流控制,面积变化与入海沙量多寡关系密切;④ 整个浑浊带区域悬沙浓度受入海沙量锐减决定,2000-2009 年较1959-1999 年悬沙浓度减小约为24.73%,向海延伸减幅降低,且峰值区域向口内移动,泥沙再悬浮作用对维持最大浑浊带悬沙浓度起调节作用,但不能决定其锐减趋势;⑤ 北槽航槽最大浑浊带的悬沙浓度向海为低—高—低变化特点,受入海沙量锐减、北槽分流分沙比减少及床沙粗化等影响,使其上段和下段悬沙浓度减小趋势,而中段受南导堤越堤沙量的影响悬沙浓度呈增加趋势。

关键词: 趋势及成因, 长江河口, 最大浑浊带(TMZ), 悬沙浓度

Abstract: Based on the analysis of suspended sediment elements at estuaries, influences of human activities and estuarine regulation projects on the turbidity maximum zone are studied. Data comes from the measurement between 1959 and 2011. It is found that human activities had little effect on the seawards water and that the sharp decrease of sediment volume and concentration in runoff led to the sharp decrease in the estuary. The concentrations off the coast and at Hangzhou Bay did not change. The concentrations along the coast of northern Jiangsu decreased a little and had no influence on the turbidity maximum zone. Affected by the hydrodynamics of runoff and tide, the area of maximum turbidity zone is related to the volume of seawards sediments. Comparisons between 1959 and 1999 show that the concentrations in 2000-2009 decreased by about 24.73% and the range reduced along the river to the sea. The peak of concentration moved upstream in the estuary. The suspended sediment concentrations in North Passage are low in upstream and downstream reaches because of the decrease of seawards sediments, spilt ratio and coarsening of bed material. In the middle of the North Passage, the concentrations increased because of the influence of the sediments across the north jetty.

Key words: suspended sediment concentration, Yangtze River Estuary, trends and causes, turbidity maximum zone (TMZ)

杨云平, 李义天, 孙昭华, 樊咏阳. 长江口最大浑浊带悬沙浓度变化趋势及成因[J]. 地理学报, 2013, 68(9): 1240-1250.

YANG Yunping, LI Yitian, SUN Zhaohua, FAN Yongyang. Trends and causes of suspended sediment concentration variation in the turbidity maximum zone at the Yangtze River Estuary[J]. Acta Geographica Sinica, 2013, 68(9): 1240-1250.

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