A Study On The Mechanism Of Meandering Rivers Under The Influence Of Riparian Vegetation

The dynamic process of meandering rivers will affect the growth and distribution of riparian vegetation,and the dynamic growth process of riparian vegetation also affects the the dynamic process of meandering rivers,there is a complex coupling dynamic mechanism between the two.It is not clear at present that the coupling dynamic mechanism between riparian vegetation and meandering rivers.In order to reveal the coupling mechanism between riparian vegetation and meandering rivers,using two methods of theory and numerical simulation to study the coupling relationship between the dynamic process of vegetation growth and meandering rivers.In theory,based on the nonlinear theoretical solutions of meandering rivers,no longer assumed that riparian erosion degree E is constant value.Vegetation factors is taken into account of bank erosion,vegetation dynamics model is introduced to describe the dynamic process of vegetation growth so as to establish a new model of bank erosion.Under the condition that the river bend is swinging slightly,using perturbation theory to establish nonlinear theory of meandering rivers considering dynamic process of vegetation growth.Theoretical results show that the ratio of vegetation growth rate to meandering river rate,vegetation density and vegetation density distribution affect the evolution of the form of the river bend.By analyzing the shape of river bend curve under the influence of vegetation,the types of meardering river can be divided into three types: the hydrodynamic condition dominant,the hydrodynamic condition and vegetation co dominant type,and the vegetation dominant type.theoretical analysis is mainly limited to small and linear conditions.In fact,there is a large nonlinear process of meandering rivers.In order to explore the coupling mechanism of the vegetation-river bend evolution under large amplitude and nonlinear conditions,the numerical simulation study is carried out.Theoretical analysis can guide the research direction of numerical simulation,and numerical simulation can expand the scope of theoretical research,and further reveal the coupling mechanism of riparian vegetation and meandering rivers.Analoging to the concept of coupling mechanism of meandering rivers and valley topography deposition,establishing a coupled dynamic model of meandering rivers and dynamic process of riparian vegetation growth.The evolution process of a curved river under the influence of different riverside vegetation models and different vegetation parameters is simulated.The simulation results show that the coupling effect between riparian vegetation and meandering rivers is obvious when the cycle of vegetation growth is close to the cycle of meandering rivers.At the same time,it is found that the riparian vegetation enhances the Long band of river curve,which indicates that there is a "resonance" mechanism between riparian vegetation and meandering rivers.Defining the vegetation influence parameters and the river coupling parameters to measure the interaction between riparian vegetation and meandering rivers.Through two parameters,the relationship types between river and riparian vegetation are divided into three types: river dominated,strong coupling and weak coupling.It is also recognized that the ratio of the cycle of vegetative growth to the cycle of meandering rivers is the key factor determining the type of the dynamic relationship between riparian vegetation and meandering rivers.