长江中下游河流地质作用与河道演变

On river geologic action and channel evolution of middle and lower Yangtze river

河流水动力是改造河床与河岸最活跃的外力因素 ,不断地发生对河谷地质体的侵蚀、搬运和沉积—即河流地质作用。河道的演变与河流的地质作用密切相关 ,而河流地质作用受到河谷地质结构的制约。从河谷地质结构与河流地质作用的观点 ,对以下几方面进行探讨 :①河流与其依托的河床河岸相互作用塑造了河道的形象 ;河流以其流量、流速、流向、流态随时空的变化 ,其地质作用的方式、强度也随之变化 ,由此发生了河道的演变。②河床河岸地质结构对河流地质作用的制约主导着河道演变的趋势。③对长江中、下游河道现状的分析研究 ,探索不同河段的河道形态与河床河岸地质结构、河流地质作用的关系。探索长江中下游河道演变的特点及影响因素 ,以期认识河道演变的某些规律 。

Dynamic forces of water in a river are the most active external factors to reform the bed and bank of the river, resulting in constant erosion, transportation, deposition of geologic bodies in the river valley, i.e. geologic action of the river. The river evolution and its geologic action are closely correlative, and the geologic action of a river is restricted by the geologic structure of the river valley. From the viewpoint of river valleys structure and rivers geologic action, the following respects are discussed:① The interaction between river flow and associated river bed and bank moulds the configuration of the river channel, the discharge, velocity vector and parttern of the river flow change with time and space, therefore the mode and intensity of the rivers geologic action also change, resulting in river evolution. ② The restraint of geologic structure of river bed and bank on the rivers geologic action controls the river evolution trend. ③ Investigating and analyzing the present conditions of the middle and lower reaches of the Yangtze river, it is probed into the relations of the river morphology with the geology structure of river bed and bank and with the rivers geologic action; probing into the characteristics and affecting factors of river channel evolution, it is purposed to recognize some rules of river channel evolution then find out the technology and method for macro control of river regime.