Study On The Influencing Factors Of Water Environmental Quality In Dianchi Lake Basin Based On Structural Equation Model

Dianchi Lake presents a serious state of eutrophication and a sharp decline in water quality with the rapid development of economic and urbanization. There is an intricate relationship between socio-economic, land use and water quality within the basin range. Multitudinous factors might have effect on quality of water environment. To study the relationship between water quality, socio-economic and land use and find out the key factors that affect water quality is of great significance for the protection of Dianchi Lake water environment and integrated management.This research used the Structural Equation Modeling to study factors that influence the water environment quality of Dianchi Lake. Taking socio-economic development, land use and water pollution as model latent variables, selecting the possible factors as measurement index of each latent variable, and according to the causal relationship between water quality, socio-economic and land use built the hypothetical model. This research used8sub basins data of Dianchi Lake in2008as the model sample, and used Bootstrap method to realize the sample augment. Though model parameter estimation, fitting inspection and modification, the optimal model to figure out the affecting relations and the degree of influence among factors and between factors and indicators was obtained. This study also presented the suggestions on integrated river basin management based on the optimization model.The results showed that socio-economic was the dominant factor to influence water quality of Dianchi Lake basin, which not only had direct impact on water environment quality, but also had indirect impact through the change of land use patterns on it. Among the socio-economic factors which had significant influence on water quality, the increase of urbanization rate, GDP annual growth rate, animal husbandry and unit area output growth of farming could exacerbate the water pollution; Improvement of output value of tertiary industry and proportion of sewage treatment rate will promote the amelioration of water environment. Among the land use factors that obviously affecting the water quality, increase of the proportion of forest land and average shape index of cultivated land could mitigate water pollution; improvement on proportion of construction land, patch density index of construction land, patch density index and degree of aggregation index of arable land could intense negative impacts on water quality.