Study On Land Ecological Quality Assessment And Evolution Mechanism Of Watershed Based On RS

Water resources in China is excessive in South and few in North,The Middle Route Project of South-to-North Water Transfer is of great significance to alleviate the water shortage in northern China.The water quality of Danjiangkou Reservoir,the source area of the South-to-North Water Transfer Project,is almost a matter of national security in China.From the perspective of long-term development,,with the rapid economic development,the excessive consumption of resources in the reservoir area,the continuous increase of population and the continuous expansion of urban construction land,the ecological quality of land in Danjiang River Basin(Henan Section)will inevitably change,which will affect the quality of water resources in the reservoir area.Therefore,analyzing the changes of land ecological quality in the study area is the basic condition for ecological protection and rational planning and utilization of natural resources,which can provide scientific data support for the protection and planning of the study area,and help to maintain the balance and sustainability developping of the regional natural ecosystem.In order to grasp the changes in land ecological quality in the research area in the past 20 years,based on remote sensing,GIS and other technologies,collect remote sensing images,socio-economic development data and other data,select indicators to construct land ecological quality evaluation index system and determine index weights;then the improved variable fuzzy set model is introduced to evaluate the land ecological quality in the study area;the differentiation of land ecological quality is analyzed by using Moran index and LISA spatial aggregation map;Finally,by constructing an evolution analysis model,quantitative analysis of the influencing factors and extent of impact on the evolution of land ecological quality,and the targeted suggestions and countermeasures are proposed.The main research contents are:(1)Establishment of land ecological quality evaluation index system in the study area.Based on the status of land ecology and socio-economic development in the study area,referring to the evaluation index system of land ecological quality at home and abroad,the evaluation index system is constructed from the ecological basis,ecological structure,ecological benefits and ecological stress of the study area.The selected evaluation indicators include RSEI,rainfall,effective soil thickness,topographic index,NPP,landscape diversity index,landscape evenness index,landscape fragmentation index,landscape dominance index,ecological land use ratio,population density.Urbanization ratio,land use intensity,per capita GDP,and ecological service value.(2)Land ecological quality evaluation model based on improved variable fuzzy sets is established in the study area.Based on the mathematical principle of the variable fuzzy set method,the calculation method of relative membership degree is improved.The relative membership degree of the index is determined by the combination of the central point triangle whitening weight function and the relative difference function,and combining the evaluation Index weights which determined by the relative entropy theory,the ecological quality of the land in the study area are evaluates and analyzed.The results of land ecological quality assessment in the study area.The results show that,in the past 20 years,the ecological quality of the land in the study area has gradually improved.Among them,the area of middle and general grade of land ecological quality changed most obviously.Further analysis of the temporal and spatial changes of land ecological quality revealed that the area of the ecological quality of the study area deteriorated(significantly deteriorated and slightly deteriorated),and the area of the area decreased significantly(apparently improved and slightly improved).It shows that the overall ecological quality of the land in the study area is gradually increasing in the past 20 years,but the ecological quality of the land has been declining due to human activities in some areas.(3)Spatial correlation of land ecological quality in the study area.The spatial correlation analysis of the land ecological quality of the study area is carried out by using Geoda software,and the Moran's scatter plot and LISA cluster map of the land ecological quality of the study area are obtained.The Moran's index of land ecological quality in the study areas in 1998,2008 and 2017 was 0.7901,0.7258 and 0.7492,respectively,indicating that the spatial distribution of land ecological quality in the third phase of the study area showed a positive correlation,and the degree of aggregation first decreased and then increased.The spatial distribution shows a characteristic of "homogeneous agglomeration and heterogeneous isolation".It can be seen from the LISA clustering map that the agglomerated areas with higher ecological quality of the land are mainly distributed in the central and northern parts of the study area,and the concentrated areas with poor ecological quality of the land are mainly distributed in the northeast and southern areas of the study area.(4)Quantitative analysis of the evolution mechanism of land ecological quality in the study area.Construct a quantitative analysis model of land ecological quality evolution in the study area,calculate the impact degree of each evaluation index on the land ecological quality of the study area,and quantitatively analyze the influencing factors of the land ecological quality evaluation in the study area.The results show that there are some differences in the main influencing factors of land ecological quality in counties and districts in the study area,which indicates that the causes of land ecological quality changes in different counties and districts in the past 20 years are not the same.The top 5 influencing factors are the dominance index(C9),the ecological land use ratio(C10),the population density(C11),the per capita GDP(C14),and the RSEI(C1).