从河相关系定性探讨长江口澄通河段河床演变趋势

Analysis of riverbed evolution trend of Chengtong reach in terms of river facies relation

利用长江口澄通河段多年实测水深、流量等资料,建立反映澄通河段典型断面面积随含沙量和落潮流量变化的河相关系。依据所建立的各典型断面的河相关系式,分别探讨在含沙量变化和落潮流量变化下,典型断面面积的变化情况。分析可知,当含沙量从0.312 kg/m3减少到0.043 kg/m3时,各典型断面的面积普遍增加超过55%,而当落潮流量从10 000 m3/s增加到100 000 m3/s时,典型断面面积增加了约7.7倍。这表明在落潮流量不变的前提下,含沙量的减少会导致澄通河段各典型断面面积较大幅度地增大,而在含沙量保持不变的情况下,随着落潮流量的增加,断面面积的增加也较为明显。

This paper presents an analysis of the riverbed evolution trend of Chengtong reach of the Yangtze River in terms of the river facies relation,with the main focus on the change of the sectional area of typical section under the different discharge and sediment concentration.The result shows that when the sediment concentration decreases from 0.312 kg/m3 to 0.043 kg/m3,the sectional area of typical section increases 55%.At the same time,while the discharge of ebb tide increases from 10 000 m3/s to 100 000 m3/s,the sectional area increases nearly 7.7 times.These indicate that under the current status of continuous decrease of sediment concentration from the upstream,the occurrence of overall erosion in the Chengtong reach is highly possible in the future.In addition,the sectional area will increase also if the discharge from upstream increases.