江道采砂对椒江河口的影响分析

椒江河口以牛头颈口门为界,分为口内和口外,口内为椒江、灵江和永宁江,口外为椒江口。一般情况下,随着椒江流域径流丰枯变化,泥沙在口外与口内之间来回搬运,口内河床呈"洪冲潮淤",口外相反,自然状态下总体较为稳定。1990后,椒江河口河床呈持续下降的异常变化,且口内下降幅度明显大于口外,本文通过分析河口区近期潮动力变化和各类工程的影响特点,认为近期异常变化主要是由于口内椒江和灵江江道采沙引起,并采用河口河相关系对椒江口断面变化幅度进行验算。

Effect of evacuating sand on Jiaojiang River estuary

Niutoujing on the mouth sand bar separates the Jiaojiang River estuary into two parts.The inner region is Jiaojiang River,Lingjiang River and Yongning River and the outer region is Jiaojiang River estuary.In ordinary circumstances,the sediment is transported back and forth between the outer and inner mouth bars with the variation of high and low runoff in Jiaojiang River basin.The phenomenon of scouring during floods and silting during tides emerges in the bed inside the mouth bar,but it is opposite for the bed outside the mouth bar,and in general the bed is stable under the natural condition.After 1990,an exceptional change in Jiaojiang River estuary bed was taken place and the bed was continuously dropped.The drop scope inside the mouth bar was obviously larger than that outside the mouth bar.The analyses show that the short-term exceptional variation is caused mainly by evacuating sand in Jiaojiang River and Lingjiang River on the mouth bar.And the sectional variation scope of Jiaojiang River estuary has been verified by estuarine hydraulic geometry.