Study On Ecological Connectivity Of Plain River Network Based On Edge Connectivity In Yangzhou City

With the development of social economy,people on the development and utilization of rivers and lakes water system has been increasing.The pattern of water system was changed,the original connected structure between rivers and lakes have also been broken.Based on the theory of ecosystem integrity and the concept of basement,corridor and patch in landscape ecology,this paper discusses the influence of water system connectivity on the structure and function of water ecosystem.This article puts forward a quantitative evaluation method of edge connectivity by the graph theory,which's foothold is the influence of water system physical connectivity on the structure and function of aquatic ecosystem.Taking the main urban water system of Yangzhou City as an example,the connectivity degree of the local rivers and lakes is calculated,and its ecological connectivity is evaluated.This study can provide technical support for the optimization of connectivity distribution,river ecological restoration and improvement of aquatic environment.The main research contents and research results mainly include the following aspects:(1)The theoretical basis of rivers and lakes ecological connectivity are analied.The analysis of the water system connectivity should be researched from the ecosystem's integrity.The conceptual model of the river ecosystem structural function is based on the integrity of the ecosystem.In this theroy,the river four-dimensional continuum model is the most important theoretical basis of this study.The study of landscape pattern and connectivity in landscape ecology theory provides the idea and reference for the method proposed in this issue.The physical connection of water system has important influence on the stability of ecosystem structure and process continuity,and also makes the river landscape fragmentation influences.(2)Elaborating a quantitative evaluation method for edge connectivity of rivers and lakes.The evaluation process of "water extraction-map model construction-connectivity calculation" was established.Three kinds of water extraction methods including remote sensing image,DEM,Google Earth and their application range are proposed at the first.Then the technology based on GIS to construct the graph model and adjacency matrix tools are studied.Finally,the calculation process of edge connectivity is built.(3)The way of evaluating the connectivity degree of rivers and lakes is applied to the main urban water system of Yangzhou City.According to the present situation of water ecological environment in Yangzhou City,using Google Earth to extract water,establish graph model and adjacency matrix.Finally,the connectivity of water system in Yangzhou city is calculated by the self-developed software.(4)The ecological connectivity of rivers and lakes in Yangzhou City was analyzed.It is calculated that the connectivity degree of the main urban area in Yangzhou is 2.Although the local area of water connectivity is better,but the overall connectivity of urban rivers is low.Through the connectivity analysis to identify the two main urban water system connected to the most sensitive river.