钱塘江河口区不同河段表层沉积物粒度特征及其对水动力的响应  

Grain size characteristics of the surface sediments from the Qiantang River estuary and their implication for sedimentary hydrodynamics

作　　者：刘朝[1] 师育新[1] 戴雪荣[1] 席雅娟[1] 

机构地区：[1]华东师范大学地理科学学院,上海200241

出　　处：《华东师范大学学报（自然科学版）》2016年第6期182-191,共10页Journal of East China Normal University(Natural Science)

基　　金：国家自然科学基金(41371214)

摘　　要：钱塘江河口区为典型的喇叭形强潮型河口,受径流、潮流和长江沿岸流及其挟带泥沙的影响,沉积动力环境较复杂.本文通过对钱塘江枯水大潮潮区界(芦茨)以下(近口段、河口段和口外海滨段)表层沉积物的系统采样,分析了其沉积物类型和粒度组成在河口区不同河段和南、北岸的空间分布特征,并探讨了沉积动力环境.结果显示:钱塘江河口区表层沉积物以粉砂、粘土质粉砂为主;从上游至下游,三段沉积物粒度呈细-粗-细的空间变化特征,偏度相应表现为近对称-正偏、极正偏-正偏的特点,频率曲线峰型则具有多峰-高窄峰-矮窄峰的分布规律.其中,河口段受径流和潮流共同作用,在强潮环境下,表层沉积物粒度最粗,分选性最好.河口段和口外海滨段的南、北岸表层沉积物粒度也存在明显差异,反映北岸水动力相对南岸更强.Pejrup三角图分析表明,研究区水动力条件总体较强,其中河口段的水动力最强,不同河段沉积物粒度特征对水动力强度有很好的响应.The Qiantang River estuary is a typical funnel-shaped, strong tidal estuary. It extends 274 kmlong from the tidal limit （at Luci） down to the mouth of Hangzhou Bay and possesses a complicated sedimentary hydraulic environment. This paper focuses on the grain size analysis of the surface sediments （68 samples in total）taken from the near-bank underwater bottom. The grain size characteristics, types of sediments and their spatial distribution and the possible causes are discussed. Studies have shown that the sediments are mainly composed of silt and clayey silt. According to grain size composition,the estuary can be divided into three parts： the upper,middle and the lower. The sediments from both the upper and the lower parts are finer, poorer sorted than those from the middle part. The skewness parameter （SK） is featured with sub-symmetric-positive bias in the upper part while very positively skewed-positive bias in the lower part. From upstream to downstream the frequency curve shows different peak types of multi-peak, high and narrow peak and low narrow peak. These differences in sediment composi- tion and textures must have matched the different sedimentary hydrodynamic environment the runoff in the upper part, alternative of runoff and tide in the middle, and mainly the tidal environment in the lower. As indicated by Pejrup triangulation, the hydrodynamic environment of this estuary is relatively strong, especially in the middle part, and the grain size characteristics show close relation to the hydrodynamic environment.

关 键 词：沉积物 粒度 水动力 河口 钱塘江 

分 类 号：P931.1[天文地球—自然地理学]