The Yangtze River Delta Ecological Security Assessment And Early Warning Research Based On Catastrophe Theory And Grey Prediction Model

The city is the region where human production,life and material culture are the most closely exchanged.With the development of society,the urbanization process is further accelerated,the natural ecosystem is significantly affected by human beings,and human beings are under increasing pressure on the original ecological environment.The problem is getting more and more prominent.China's ecological security has risen to the level of national security.It can be seen that ecological security is of great significance to the stable development of society.The Yangtze River Delta has a high degree of urbanization,and its economic development and social conditions have certain typical characteristics.This paper takes the Yangtze River Delta urban agglomeration as the research area,and constructs the urban ecological security evaluation index system based on the PSR(pressure-state-response)model.28 specific indicators are selected from the social,economic and natural aspects.The time span is 2005-2015.Entropy weight method,PSR model modeling,catastrophe progression method and GM(1,1,)mean method prediction,from the perspective of time change and spatial change,the total system layer,pressure layer and state layer of the Yangtze River Delta Analysis and prediction of the ecological security status of the response layer.Research indicates:(1)Time variation characteristicsThe systemic layer of ecological security in the Yangtze River Delta has changed with time and is on the rise.In 2005,the overall ecological security level of the Yangtze River Delta was low.Except for Hangzhou,Shaoxing and Jinhua,the rest of the cities were in a relatively unsafe and extremely unsafe range.With the development of time,the ecological security level of the Yangtze River Delta is on a positive upward trend.By 2015,except for Shanghai(0.9578),which is in a safer and safer range,Hangzhou is the highest value(0.9841),indicating that the overallecological security level in the Yangtze River Delta region is high,but there is no The ecological security level of a city has reached an ideal state,and there is still room for further development of regional ecological security.The ranking of eco-safety development level of the Yangtze River Delta in 2015 is from high to low: Hangzhou,Shaoxing,Ningbo,Nanjing,Jinhua,Huzhou,Zhenjiang,Taizhou,Suzhou,Zhoushan,Wuxi.Nantong City,Changzhou City,Jiaxing City,Hefei City,Chizhou City,Yangzhou City,Wuhu City,Tongling City,Xuancheng City,Yancheng City,Taizhou City,Maanshan City,Anqing City,Zhangzhou City and Shanghai.(2)Spatial variation characteristicsIn 2005,the cities with relatively high ecological security in the Yangtze River Delta were concentrated in the southwestern regions,and the cities with lower ecological security indexes were mainly concentrated in the northwestern regions.The number of cities in the less secure state was greater than the number of extremely insecure.By 2015,except for Shanghai,which is in a less secure state,the rest of the cities are in safe or safer levels.Among them,Hangzhou,Shaoxing and Ningbo have higher ecological security levels and reach a safer state.Most cities are in a safe state.The spatial pattern shows that the ecological security level in the south is high,and the rest of the cities are in a safe level,that is,uniform.(3)Prediction resultsThe mean GM(1,1)model was used to predict the ecological security status of the Yangtze River Delta in 2019 and 2023.The results show that the ecological security pattern of the 2019 Yangtze River Delta is higher in the south and middle,and lower in the north.In addition to Shanghai's relatively unsafe state,25 cities have reached a safe level,of which 10 cities are in a safe state,14 cities are in a safe state,and 1 city is in an ideal state,indicating that the ecological security level in the Yangtze River Delta is better.Development,the overall ecological security level of the region is relatively high.By 2023,the ecological security of the Yangtze River Delta is characterized by a higher profile in the southwest,with Shanghai being in a less secure state,Chizhou,Xuancheng and Hangzhou reaching an ideal state,and the rest of the cities are in a safer state,indicating a long The level of triangular ecological security has been further developed and characterized by spatial synergy.