Research On Changes Of Ecological Environment In Qinghai Lake Watershed Based On Multi-source Remote Sensing Data

Since the 1950 s,the ecological problems,such as the degradation of grassland,the decrease of lake area,the increase of land desertification area and the decrease of biological abundance in Qinghai Lake Watershed,aroused widespread concerns from national,local governments and related scholars.The researches on the trend of ecological environment changes and the analysis of possible causes can help to improve people's awareness of environmental protection and provide some references for the government and the state to formulate relevant laws and regulations,which can promote the sustainable development of regional economy.In this master thesis,based on the multi-source remote sensing data,we evaluated the ecological environment of Qinghai Lake Watershed in 2000,2004,2006,2009 and 2013.And then,we analyzed the trend of the ecological environment in recent years with the support of GIS technology.Finally,we gave the reasons from two apsects of natural factors and human factors.The main work and achievements were concluded as follows:(1)According to the characteristics of natural environment and social economy in Qinghai Lake Watershed,we extracted nine indexes of Fractional Vegetation Cover(FVC),Temperature Vegetation Drought Index(TVDI),Net Primary Productivity(NPP),Land Type,Land Sruface Temperature(LST),annual Rainfall,DEM,Slope and Wind Speed based on the multi-source remote sensing data of Landsat,MODIS,TRMM,ASTER GDEM and ERA-Interim in Qinghai Lake Watershed.And then,using the MODIS land cover product,the land use transfer matrices and ecological carrying capacity of Qinghai Lake Watershed were calculated and the land use/cover changes in Qinghai Lake Watershed were analyzed.Finally,the maximum difference normalization method was improved,which was used to standardize the nine indicators.(2)We used the principal component analysis(PCA)and the analytic hierarchy process(AHP)to calculate the weights of the nine indicators respectively.Although the weights of the nine indicators determined by the two methods were different,the trend of ecological environment in Qinghai Lake Watershed was consistent.From the evaluation results,it is showed that the ecological environment of Qinghai Lake Watershed had a good trend as a whole from 2000 to 2013 and the ecological environment got slightly worse from 2009 to 2013.From the spatial distribution of Qinghai Lake Watershed,the ecological environment of the area around Qinghai Lake in the southeast was obviously better than that in the northwest.(3)From the two aspects of climate changes and human factors,this thesis analyzed the potential causes of changes of ecological environment in Qinghai Lake Watershed.Among of them,the attentions from the state and the local government played a positive role in imporving the ecological environment of Qinghai Lake Watershed.