河网型分汊河口分流比影响因素探究——以珠江蕉门口为例

Research on the effect factors of flow division ratio in river networks bifurcated estuary:A case of Jiaomen outlet,the Zhujiang River Delta

珠江蕉门河口是典型的河网型分汊河口,是珠江口重要的泄洪排沙通道,其分流比变化对珠江三角洲地貌演变、防洪与航运等至关重要。本文基于蕉门近期地貌形态,以凫洲水道落潮分流比为研究对象,设计系列水槽实验,选取分汊河道断面形态与分汊角两个影响因素进行敏感性分析,探究河网型分汊河口分流比随上述因子的演变规律。结果表明:在分汊河道断面形态稳定的基础上,凫洲水道分流比与虎门、蕉门相对流速有较好的相关关系,受两口门绝对流速的影响较小;分流比与蕉门南水道水深呈负相关,与凫洲水道水深呈正相关;分汊角在30°~65°区间内,分流比与分汊角呈负相关,分汊角在65°~75°时,分流比与分汊角的正负相关关系在流速比V=0.7前后转换;通过量化各变量敏感性,分别得到凫洲水道分流比增大或减小对上述因子的敏感性大小。研究成果可为蕉门整治工程提供参考依据。

Jiaomen outlet is a typical river network bifurcated estuary and an important channel for flood discharge and sediment discharge of the Zhujiang River.The change of diversion ratio in bifurcated Jiaomen outlet is crucial to the geomorphological evolution,flood control and navigation safety of the Zhujiang River Delta.This study de-signed a series of flume experiments,and selected sensitivity analysis parameter which includes the water depth of bifurcated channel and bifurcated angle to explores the evolution of the flow division ratio of the river network type bifurcated estuary with the above factors.The dimension of the physical model is based on the recent geomorphic morphology of Jiaomen outlet.The result show that,on the basis of the stability of the section feature of the bifurc-ated channel,the flow division ratio of Fuzhou Channel depicts a good correlation with the flow velocity ratio between Humen and Jiaomen,and is less affected by the absolute flow velocity of the two outlets.Subsequently,the sensitivity experiment result indicate that the flow division ratio is negatively correlated with the water depth of Jiaomen South Channel and positively correlated with the water depth of Fuzhou Channel,and when the bifurca-tion angle is between 30°and 65°,the flow division ratio is negatively correlated with the bifurcation angle,but when the bifurcation angle is between 65°and 75°,the positive and negative correlation between the flow division ratio and the bifurcation angle changes around the velocity ratio V=0.7.Then,the sensitivity of the increase or de-crease of the flow division ratio to the above each variable can be obtained by quantifying the sensitivity experi-ment result.The research results can provide reference for artificial regulation project of Jiaomen outlet.