Research On Temporal-spatial Evolution And Ecological Restoration Of River Landscape Corridor In Zhengzhou Under The Background Of Urbanization

River landscape corridor is an important part of urban ecosystem as well as the carrier of urban environmental elements and featured landscape.The rapid urbanization process has a great impact on the Spatio-temporal pattern of river landscape corridors and water ecological health,and the contradiction between people,river and city is becoming increasingly prominent,which has become the focus of various disciplines.On the basis of systematically sorting out relevant theories of river landscape corridors and clarifying the development and internal relationship of river landscape corridors and ecological restoration research,this dissertation proposes the research idea of "river landscape-evolutionevaluation-restoration".From the perspective of landscape architecture planning and research,taking the dynamic change of urbanization,land use and river evolution in Zhengzhou City,Henan Province as the starting point,The author studies the temporal and spatial evolution characteristics of river landscape corridor,constructs the ecological health evaluation system of urbanization river landscape corridor,and puts forward the ecological restoration strategy for urban river landscape corridor.Firstly,Using the combination of remote sensing(RS)and geographic information system(GIS),based on the satellite remote sensing data of seven typical periods from 1980 to 2018,this dissertation interprets and analyzes the land use and surface cover changes in Zhengzhou city and the main urban area,and quantitatively describes the land use types and their temporal and spatial evolution law in different periods of Zhengzhou city.Based on the above data,the author obtains the index data of river landscape corridor connectivity and structural form in Zhengzhou in recent 40 years,constructs the index evaluation system of"structural form network connectivity and blue-green-gray space" of river landscape corridor,makes a coupling analysis of urbanization development level and temporal-spatial evolution of river landscape corridor,and reveals the dynamic growth and decline relationship between"urbanization-land-river" and verifies that urbanization and building land change are important driving forces for the evolution of river landscape corridor,especially the increase of building land(gray space)is significantly related to the change of river corridor indicators.With the process of urbanization,the connectivity index of river landscape corridor inZhengzhou tends to decrease first and then increase slowly,and the inflection point is concentrated between 2005 and 2010;In Zhengzhou,the main urban area and the administrative areas under the jurisdiction of Zhengzhou,the river landscape corridor area,Blue-green space area and other structural morphological indicators are decreasing year by year,and show obvious characteristics of spatial and temporal differentiation.From the perspective of spatial dimension,the area of river landscape corridor in Zhengzhou city,main urban area(central urban area)and all administrative areas under the jurisdiction of Zhengzhou city shows a downward trend.The connectivity index between the city and the main urban area shows a downward trend at first and then an upward trend,but the recovery rate is less than the reduction rate,In recent years,the new urban area(Zhengdong New District)and suburb(Huiji District)of Zhengzhou are the main areas for the improvement of corridor connectivity and blue-green space,but the improvement of various indicators in the original urban area(Jinshui District,Erqi District,Zhongyuan District and Guancheng District)is relatively slow,which is related to the relatively limited green space and water space available for expansion in the original urban area of Zhengzhou.From the perspective of urbanization process,the water system decaying in the early stage of urbanization is mainly in natural water system,and the water system increasing in the later stage of urbanization is mainly in artificial water system.Human factor has become the main driving force of river landscape corridor evolution.Secondly,By means of factor analysis and rotation analysis of 26 factors,16 indexes of ecological health status evaluation of river landscape corridor are constructed to reflect five functions:social function,water ecological function,habitat and channel function,water landscape function and space function.The typical sample plots were investigated in different river sections,and the results showed that the river landscape corridors in Zhengzhou had prominent problems in social function,water ecological function,habitat and channel function,and 62.1%of the river sections were in sub-health.Among the 14 indicators(87.5%),Zhengdong New District and suburbs(Huiji District)are better than original districts(Jinshui District,Erqi District,Zhongyuan District and Guancheng District).The flood control function,eutrophication of water body and naturalization rate of revetment in the original city are significantly lower than those in Zhengdong New District and Huiji District,The original urban area should be the focus of urban river corridor ecological restoration.From the survey and evaluation of ecological health status of typical river segments,the order is:Jialu River>Dongfeng Canal>Jinshui River>Xionger River,that is,the overall health status of river landscape corridors in new urban areas and suburbs is better than that in original urban areas.Based on this,the key areas,key rivers,key river segments and main index items of ecological restoration of river landscape corridor in Zhengzhou city were determined.Finally,From the perspective of landscape architecture,ecological restoration schemes of engineering measures and non-engineering measures were put forward according to the three levels of macro(watershed level),middle(urban level)and micro(river reach level),and the restoration strategy of "small watershed planning+three warter(hydrology,water quantity and water quality)"was constructed at the macro level.At the meso level,the restoration strategies of blue-green interweaving,blue-green link,blue-green fusion and elastic blue-green were adopted.At the micro level,the restoration strategies were mainly engineering measures.By studying the relationship between "people,river and city"under the background of urbanization,taking Zhengzhou as an example,this dissertation constructs the river landscape corridor health evaluation system and the river landscape corridor ecological restoration system based on three dimensions and three levels,in order to provide ideas and approaches for the transformation of urban river landscape corridor,ecological restoration and the construction of blue-green space.It has a guiding role in river health,water ecological restoration and improvement of water ecological quality in Zhengzhou,and has a certain reference significance for water landscape construction in small and medium-sized cities with low urbanization level.