The Spatial And Time Series Processes Of Dianchi Basin LUCC And Their Interactive Effect With Water Conditions

Land is the resource on which human activities depend for survival.In the past 30 years,Kunming has developed at a high speed and the city continues to expand outward.There is a large amount of woodland,grassland and so on transformed into urban construction land,natural bare soil and vegetation cover reduced.As a result,the surface hardening is serious,and the water seepage in the water circulation system is obviously reduced,which causes great damage to the water environment in the Dianchi Lake.At the same time,industrial wastewater and domestic wastewater enter Dianchi Lake with surface runoff and Rain Water scour,which causes the water quality of Dianchi Lake to be degraded from Class III water body to inferior Class V water body in 1980’s.Through collecting the water quality data of Dianchi Lake from 1999 to 2013,this paper analyzes the land use and its change in Dianchi Lake Basin by means of remote sensing and GIS,and explores the temporal and spatial processes of land use and water quality change in Dianchi Lake.On this basis,the relationship between different land use types and water quality is quantitatively discussed by distance attenuation function and heavy mechanics model.From the perspectives of land use/cover change trend,spatial characteristics and transfer dynamic rate,this paper analyzes the spatial-temporal change process of land use/cover change in Dianchi basin from multiple perspectives.Through statistical analysis,spatial influence analysis,correlation analysis and other methods,quantitative analysis of the interaction process between land use / cover change and Dianchi water quality changes,providing a scientific basis for the future construction and urban development of Kunming.The main findings of the study are as follows:(1)Through the comparison of various land use extraction methods,the combined image classification method is used to classify the land use in Dianchi Lake Basin.The results show that this method can achieve a better classification result.Its overall accuracy is 91.83%,and the kappa coefficient is 0.89.This indicates that the classification results are highly consistent with the real objects,and the method can be applied to classify the continuous time series of the basin land.(2)The research results show that the cultivated land has changed to grassland,woodland and construction land since 1999—2013,and the urban construction land area has been on an upward trend,and the urban construction land has the highest expansion rate,reaching a total growth rate of 94.3%.the cultivated land and unused land reduced by 66.61%,66.01%.All types of land expansion and reduction are tested by α=0.05.During the years of the study,it was found that Kunming gradually formed a development pattern with four urban districts radiating from the core to the periphery.(3)Although the water quality of Dianchi Lake has improved in the past 10 years,Caohai is still a poor V-type water body.The water quality of the outer sea is better than that of the Caohai.This is because the Caohai is close to the main urban area,and the surface runoff brings a lot of life and industrial wastewater.Generally speaking,the water quality of Dianchi lake is improved in fluctuation.(4)Using the gravity model and the distance attenuation function to analyze the land use types and the spatial influence of each sub-basin,under the dual effects of distance and area,it is found that all types of land have high spatial influence in Jinjianghe Sub-basin,Xinhe-Yanglianghe Sub-basin,Liang The Wanghe River Subbasin and the Baoxiang River Sub-basin,and the forest land also has relatively high spatial influence in the Panlongjiang North Sub-basin,which is far away from Dianchi Lake.(5)The correlation test found that there is a significant correlation between the spatial influences of different land use patterns and the water quality of Dianchi Lake.The water quality indicators under the combined effects of various land use types are most affected by urban construction land,and water temperature,biochemical oxygen demand,ammonia nitrogen are all affected by urban construction land;The cultivated land and grassland have a strong correlations between PH and BOD;The forestland and grassland have a positive effect on water quality,while the cultivated land and urban construction land have a negative effect on water quality,and there is a strong negative correlation between urban construction land and water quality.