Study On The Dynamic Evolution And Response Mechanism Of City—Water System Pattern

Urban water system is one of the most intense areas where natural processes and human activities influence each other.The rapid urbanization process and extensive economic development model have led to changes in the structure of urban water systems,blocked connectivity,and functional degradation,which have intensified the relationship between people and water.In order to explore the sustainable development mode of urban water system,since the 21st century,the Central Committee of the Communist Party of China and Water Department have clearly requested to promote the construction of ecological water system and river-lake connectivity project with the goal of water ecological civilization.How to scientifically explore the law of urbanization process and water system evolution,and analyze the dynamic response mechanism between them are key scientific issues in the current urban water system research and administrative decision.This paper relies on the key projects of the National Natural Science Foundation of China(Grant No.:NSCF-51739009).Taking the core cities of the Central Plains Urban Agglomeration,the typical regions of rapid urbanization and the main urban area of Zhengzhou as research object,this paper deeply explores the characteristics of urban development and water system evolution,and reveals the dynamic response mechanism between them,so as to provide reference and guidance for the construction of water ecological civilization city.The main research contents are as follows:(1)In this paper,the combined pooling dual-channel convolutional neural network is used to realize the efficient identification of land use information in the study area;the land use transfer matrix is constructed in this paper to analyze the evolution process;the urban expansion intensity is calculated based on the concentric ring segmentation unit of urban space,the characteristic parameters of urban expansion can be gained by fitting the logarithmic normal distribution curve of urban expansion intensity and distance from urban center,and then analyze the urban expansion intensity;then displays and analyzes the evolution process of urban expansion direction based on the statistics of urban expansion increment of quadrant unit divided by the same vertex fan.(2)In this paper,the principal component analysis method is used to synthesize the indexes of greenness,wetness,heat,dryness,and the Remote Sensing Based Ecological Index is constructed to realize the evaluation of ecological environment quality and the analysis of its evolution process,and grades were divided,and the evolution analysis of the structure and distribution characteristics of each grade area is realized based on GIS technology;the change direction and evolution process of ecological environment grade are revealed by dynamic monitoring method.(3)The paper puts forward water system classification criterion based on river width division;and the GIS platform is used to extract the water system information in the study area by using remote sensing results and multi-source information;and then reveals spatiotemporal evolution characteristics of quantity-structure-function of urban water system pattern selecting indices from aspects of geometric quantity,morphological structure and storage function;and at last analyze the reasons of water system evolution in the process of urbanization.(4)In this paper,the concept and connotation of water system connectivity are identified;and takes the maximum flow of the network as the dynamic connectivity of the water system and adds Flood Control Function Requirements to Arc Capacity Weight to generalize water system capacity weighting network.Then the paper establishes maximum flow mathematical model of the water network with capacity constraints and flow balance constraints,and designs a labeling algorithm based on augmenting path to solve the problem to measure and analyze the Transmission Flux Characteristics in Water Network.In this paper,the actual length of the river channel is used as the arc distance weight to generalize the water system distance weighting network;and The FLOYD algorithm is used to obtain the shortest distance matrix,and then the network diameter and average distance index are calculated to realize the measurement and evolution analysis of the transmission latency characteristics of the water network.(5)In this paper,a comprehensive evaluation index system is constructed by selecting multi-dimensional indicators to realize the quantitative evaluation of urbanization development and water system evolution;and constructs a Vector Autoregression model to study on the two-way linkage effects between Urbanization Development and Water System Evolution Comprehensive Characteristics,Quantity,Structure,Transmission,Storage and Utilization of Water Resources.In this paper,the Granger Causality Test is used to reveal the causality between variables;and the Impulse Response Function is used to analyze the dynamic impact effect between urbanization level,water system evolution and other indicators,and the variance decomposition method is used to quantitatively evaluate the importance of impact transmission.The results show that there is a significant bidirectional promotion effect between urbanization process and water system evolution,and the interaction between urbanization process and each sub-index of water system shows heterogeneity.