Study On The Evolution And Driving Mechanism Of Wetland Landscape Pattern In Three Gorges Reservoir Area

Wetland is an important natural resource.It is one of the most important ecological conditions of nature and the most important living condition of mankind.It is closely related to the survival and development of human beings.Three Gorges reservoir area as a typical domestic and international wetland resources research area,to the reservoir area has brought unprecedented opportunities for development,but also will make the reservoir area more prominent contradictions,the wetland landscape pattern and driving mechanism of the research will provide the basis for government decision-making.This paper takes Chongqingsection of the three gorges reservoir as an example,with 1990 TM,2000 ETM +,2015 OLI and Google Earth images as the data source,through the decision tree classification and supervised classification of object-oriented,obtainingthree wetland landscape distribution maps.On this basis,the landscape pattern analysis was carried out to obtain the three landscape pattern index.And then explores the driving ability of the wetland landscape pattern of economy,population,precipitation,temperature and relative humidity from 1985 to 2015.Finally,the CA-Markov model is used to predict the wetland landscape pattern of the Three Gorges reservoir area(Chongqing section)in 2030.The main conclusions are as follows:1,from the area of view,in 30 years,the total area of wetlands first decreased and then increased.On the whole,the area of wetland types increased.In the past 2000-2015 years,the areas of perpetual River,swamp meadow,pond and artificial lake showed an increasing trend,and the area of floodplain plain showed a decreasing trend.2,from the perspective of spatial structure,the water system in the Three Gorges Reservoir area is mostly grid water or dendritic River system.Floodplain Plain Wetlands are distributed along both sides of the Yangtze River,and part of them are on both sides of the tributaries.The swamp meadow all located in Wuxi County,located in the Hongchi dam area,located in the long groove,Grass Pond area.The pond is mostly distributed in low elevation area,and its distribution is obviously related to the elevation.The artificial lakes in the study area are distributed in the area where the elevation decreases abruptly relative to the surrounding area.3,from the landscape pattern index,in the 30 years,the overall number of patches in the landscape is increasing,and the fragmentation of the landscape has increased significantly.The degree of spread index decreased first and then increased.In 2015,the degree of landscape agglomeration was lowest,the ductility was higher,and the connectivity was better.Shannon diversity index and Shannon evenness index both showed the trend of increasing first and then decreasing.The average diversity index of Shannon is near 0.8,and the landscape heterogeneity is strong,and the landscape types are rich and varied.In 2000,the landscape was the most balanced,but the fragmentation was the highest,but in 2015 it showed a more stable landscape pattern.During the 30 years,the average Shannon evenness index was near 0.5,and the distribution of landscape types in the landscape was even.4,from the landscape pattern of driving force,natural factors in precipitation,relative humidity and wetland area changes were positively correlated,temperature and wetland area showed a negative correlation.Among the socioeconomic factors,economic factors and population factors are the factors that mainly promote the evolution of wetland landscape pattern.The economic factor is higher than the population factor.The policy has a significant effect on the increase in wetland area.5,from the CA-Markov model prediction,2015 prediction value and 2015 actual value contrast,Kappa coefficient is 0.747,can meet the needs of wetland prediction.In 2030,the prediction results show that the total wetland area from 136243 hectares in 2015 dropped to 135228 hectares,including permanent rivers,floodplain wetlands,swamp meadow and pond area decreased,pond area decreased by 3223 hectares of artificial lake area showed a rising trend,growth in the area of 3764 hectares,can infer the possible large the pond area into the artificial lake in the future phenomenon.