Assessment And Early Warning Of Land Ecological Security In Chaohu Lake Basin

As an important ecological function area in China,the Chaohu Lake Basin(CLB),but the regional ecological security is also affected during the rapid development of urbanization and industrialization.Therefore,it is of great significance to assessment and early warning of land ecological security(LES).Based on the Landsat remote sensing image and socio-economic statistics of the CLB in 1998,2008 and 2018,the GIS and RS technology,qualitative and quantitative analysis,model analysis and other methods were applied to analyze the land use pattern,land ecological security and early warning from the perspective of time and space.The main results of the research are as follows:(1)The characteristics of land use pattern change in CLB were revealed.The main land use types in the study area were cropland,urban land,forestland,and water area,with the largest proportion of cropland accounting for more than 60%.By occupying a large amount of ecological land,urban land led to the large-scale reduction of other land use types.The land use change during 2008-2018(1.42%)was larger than that during1998-2008(1.32%).During the study period,the spatial differences of the impacts of human activities on land use were great,and the change of land use intensity in each region indicated that there were differences in land use patterns among regions.The land use types were mainly converted between urban land,cropland,and grassland.The ecosystem service value(ESV)of cropland increased first and then decreased,while the ESV of forestland and water area decreased first and then increased.The ESV of CLB decreased first and then increased.(2)The situation and influencing factors of LES in CLB were clarified.The main ecological security problems are serious soil erosion,uneven distribution of forest resources,and serious chemical pollution of farmland.Seen from time series,the level of LES in CLB showed a trend of worsening first and then improving slightly.From the perspective of sapce,the overall ecological security situation of CLB is deteriorating,but some regions still had a improving trend.It can be found that the interaction between the influencing factors of LES showed a double factor or non-linear enhancement relationship.The per capita GDP,afforestation area,waterlogging removal area,and effective irrigated area in the human factors had significant impacts on the spatial distribution of LES,while other factors had no significant impacts.Further through risk detection,it was found that the higher the value of some driving factors,the safer the land ecology,while other factors had the opposite effects.(3)The early warning trend of the LES in CLB was explored.In terms of time,the levels of LES of the 11 regions in CLB were mainly in the status of “severe warning”and “early warning”.And the lower ranking regions were mainly due to the inadequate response mechanism,which led to the low warning level.The gray forecast model was used to predict the ecological security alert situation in 2028 and 2038,and the accuracy of the model simulation results was tested by the relative error,of which the accuracy was at the first level(good).The forecast results showed that in 2028 and 2038,the overall ecological security of the study area will develop stably,but there will be a deteriorating trend in some regions.There are 23 figures,38 tables and 182 references in this thesis.