Study Of Dynamic Change And Prediction Of Changsha Wetland Landscape Base On GSWD

With the acceleration of urbanization,the rapid development of economy and the rapid growth of population in China,the way of land use by human beings has exerted a great influence on the earth’s surface ecological environment and ecological landscape.Based on the concept of "sustainable development" and the concept of "clean water and green mountains are also golden hills and silver mountains",in order to build a resource-conserving and environment-friendly society,we have been paying increasing attention to the degradation of wetland resources and the effective protection of wetland resources in recent years.Based on the JRC Global Surface Water Dataset(GSWD),this paper takes the wetland landscape in Changsha as the research object and extracts the wetland information in the study area from two perspectives of area scale and spatial distribution.The dynamic change characteristics of wetland landscape in Changsha City from 1999 to 2019 were comprehensively analyzed.Pearson correlation coefficient and bivariate spatial autocorrelation were used to analyze the correlation between wetland area,landscape pattern and spatial distribution and natural and socio-economic factors,and comprehensively evaluate the effect of government policies on wetland landscape restoration.The FLUS model was introduced into the simulation study of wetland landscape pattern.Based on the data of driving factors,the change trend of landscape types in Changsha in the next 20 years was simulated and predicted.The main conclusions of this paper are as follows:(1)It is feasible to extract wetland information from global surface water data.This paper extracted and classified wetlands based on global surface water data combined with visual interpretation.The accuracy test results showed that the overall accuracy and Kappa coefficient were above 90%and 0.8 respectively,indicating that this method could extract wetland information efficiently and accurately.(2)The overall wetland area in Changsha showed a steady rising trend,but the area of each wetland type fluctuated greatly.From 1999 to 2019,the wetland area of Changsha has been increasing continuously.By 2019,the wetland area of Changsha has reached 239.34 km2.Among them,permanent rivers are the largest,accounting for about 35%of the total wetland area.From 2007 to 2009,a relatively large short-term fluctuation occurred in the wetland landscape in Changsha,which was manifested as the permanent rivers and lakes transformed to seasonal rivers and lakes respectively before 2008,and the reversal occurred after 2008.From 1999 to 2017,the fragmentation of wetland landscape pattern has been increasing,but since 2017,the wetland landscape has gradually improved.Among all wetland types in Changsha,the fragmentation degree of permanent river landscape is the lowest and the inter-annual fluctuation range is the largest.Pit-pond paddy field and other small wetland landscape fragmentation degree is the highest,there is no obvious inter-annual fluctuation.(3)Wetland landscape pattern is affected by natural,social,economic and policy factors.From the perspective of wetland area and landscape pattern,the area of seasonal wetland is more correlated with precipitation,while the area of permanent wetland is more correlated with runoff of Xiangjiang River.In addition,occasional extreme weather events can bring short-term fluctuations to the wetland landscape.Population growth and the extensive economic development mode in the past were the main reasons for the intensification of wetland landscape fragmentation and ecological function degradation in Changsha City from 1999 to 2017.From the perspective of wetland spatial distribution,the spatial distribution of wetland in Changsha City is negatively correlated with annual mean temperature,DEM elevation,slope,distance from road and distance from town,and positively correlated with annual precipitation and night light index.In addition,the government policy also plays a mandatory role in the change of wetland landscape in Changsha City,which promotes the rapid restoration of wetland ecosystem in local areas.(4)With the increasing awareness of ecological protection and the increasing measures taken by the government to protect wetlands,the area of wetlands in Changsha will continue to increase in the next 20 years.Among them,the area of wetland in the central and northern part of Changsha will be significantly expanded,and the number of wetland will be significantly increased,the main increase of wetland types are pothole paddy field and other small wetland.The area of wetland in the central part of Changsha City will shrink obviously,and the number of wetland will decrease obviously.The main wetland types that will change are pothole paddy field and other small wetland.Based on the global surface water data,this paper aims to continuously monitor the dynamic evolution of annual wetland landscape pattern in Changsha City from 1999 to 2019 based on the seasonal and fluctuating characteristics of wetlands,and analyze the driving force mechanism of wetland landscape pattern change from the perspectives of natural and human factors.Finally,the change trend of landscape types in Changsha in the next 20 years is predicted.The research results will provide an important scientific basis for the protection and utilization of wetlands in Changsha City,the comprehensive management of "mountains,rivers,forests,farmland,lakes and grass" system and the construction of "two-oriented society".