Time Series Analysis On The Changes Of Suburban Eco-environment And Its Driving Factors

In recent years,the process of urbanization in China has developed rapidly,urbanization improves economic development,but to our ecological environment,it has brought a significant negative impact.As an attempt to explore the ecological quality evaluation method and its driving factor analysis method,the paper uses the natural factor-based remote sensing ecological index(RSEI)to take Jiangning District of Nanjing as the research object,takes Landsat TM / ETM + / OLI_TIRS data,1994-2013 global radiation calibration night light data DMSP / 0LS,1994-2013 Nanjing Statistical Yearbook data as the main source of information,operates ENVI5.0 SP3 as a remote sensing data processing platform,combines Arcgis10.0 powerful Spatial analysis with IBM SPSS Statistics 20.0 on the ecological environment for time series analysis,hot and cold point analysis,spatial autocorrelation analysis and inter-annual trend analysis,driving factor analysis.The results show:(1)The time series of green index,humidity index,temperature index and dryness index were predicted by ARIMA model.From 1994 to 2013,the green index fluctuated with the time,and the downward trend was not obvious,The fitting value of the humidity index in the time series shows a decreasing trend,and the temperature index and the time series of the dryness index have obvious upward trend.(2)The construction of remote sensing ecological index(RSEI)is determined by the results of principal component analysis.In 1994,1997,2000,2002,2004,2006,2008,2010 and 2013,the contribution rate of the eigenvalues of the first component was 96.58%,97.44%,96.93%,94.12%,97.43%,93.33%,96.46%,97.35% and 97.26% respectively.The cumulative contribution rate of the first principal component eigenvalue was above 93.00 %,Indicating that most of the characteristics of the indicators have been concentrated.Therefore,this study can use the principal component transformation,the first principal component to represent the green,humidity,heat and dryness and other indicators of information.(3)Through the analysis of 9 TM image data,the mean values of remote sensing ecological index were 0.8527,0.8467,0.8173,0.6802,0.7154,0.8196,0.5739,0.6836 and 0.6937 respectively from 1994 to 2013.At the same time,the long-term sequence analysis of the ARIMA model shows that the overall trend of RSEI population in Jiangning District of Nanjing from September 1994 to 2013 is the time series pattern of slow decline.However,in 2010 and 2013,the trend of improving the quality of the ecological environment shows that Jiangning District has built a national ecological zone during the 12 th Five-Year Plan period,and the implementation of the blue sky action to carry out the green water and the Jinshan Yinshan plan has obvious ecological environment quality Effectiveness.(4)From the results of RSEI eco-environmental grading evaluation,the data of eco-environmental quality index in 1994,1997 and 2000 were mainly concentrated in the fifth grade(0.8-1.0),the proportion was 59.28%,60.24% and 55.56%,indicating that the ecological environment quality in 1994-2000 which mostly in the "excellent" level in space.After 2000,the ecological quality of the whole had declined.The proportion of ecological environment in the second grade(0.6-0.8)was the largest in the year of 2002,accounting for 88.08%,89.17%,79.84%,78.16%,82.54% and 78.52% respectively.It indicating that most of the ecological environment quality situation between 2002 and 2013 was at the "good" level.The quality of ecological environment is generally excellent in the 2 decades.In 2000,the demographic factors,such as the increase of population density,deforestation and urban construction,had a great influence on the quality of ecological environment.(5)From the spatial autocorrelation analysis,the correlation degree of each year was different,the spatial correlation of ecological environment quality was the lowest in 2000,Moran’s I value was 0.3797,the gathering level was significantly lower;in 1997,the spatial autocorrelation was the highest,Moran’s I value was 0.6779.With the passage of time,the spatial autocorrelation of ecological environment quality in Jiangning District showed ups and downs,and the degree of aggregation was not obvious.But in the space hot and cold spots had obvious aggregation,on behalf of the poor ecological quality of hot areas from 1994 to 2013,the gradual spread of the trend mainly in urban areas;on behalf of the ecological quality of the cold area in the south,the expansion trend was reduced in the southern part,mainly in the hilly terrain.(6)In 1994 and 2013,the ecological environment quality of Jiangning District showed a decreasing trend,and the rate of decrease was 0.0010 / 9 years.35.34% of the total area of the study area was significantly higher than that of the total area(27.40%),and the proportion of the area of the study area was significantly worse and significantly worse.The area with extremely significant deterioration and significant deterioration of the ecological environment quality was mainly concentrated in the area close to the main urban area of Nanjing and residential areas,commercial areas,industrial areas and the areas where the ecological environment quality was significantly improved and significantly improved mainly concentrated in the cattle first mountain,Tangshan,and a large number of green population of ecological tourism area which gathered high density of forests and beautiful rural leisure tourism.(7)The nighttime light index was highly correlated with the proportion of non-agricultural population and the proportion of built-up area,which was closely related to the secondary tertiary industry GDP.There was a significant correlation between the proportion of non-agricultural population and the proportion.It highly correlated with built-up area,and the second and third industry GDP.Pearson correlation coefficient were greater than 0.7.Night light index,the proportion of non-agricultural population,built area,the second and third industry GDP are closely related with the urbanization index,it could be said that these drivers to promote the process of urbanization,the development of urbanization played a very important role,a high degree of correlation with several urbanization factors combined can well reflect the urbanization index.(8)Through the analysis was of the relationship between the remote sensing ecological index and its driving factors in Jiangning District,it could be concluded that the ecological environment quality was not related to the monthly mean temperature,the correlation coefficient was only 0.295,the ecological environment quality and the monthly average precipitation,urbanization The correlation coefficient was-0.779,-0.723,and the correlation coefficient was 0.934,which was not correlated with the temperature,and the correlation coefficient was only 0.241.The correlation coefficient was-0.779 and-0.723 respectively.The improvement of the urbanization level leads to the increase of the urban built area,and the change of the urban underlying surface will directly or indirectly relate to the dynamic change of the urban climate.At the same time,the monthly average precipitation and urbanization index are highly negatively correlated with the ecological environment.With the acceleration of the urbanization process,the increase of urban precipitation will lead to the increase of rainstorm weather,which will aggravate the urban flood control pressure and the ecological environment destruction,the quality of the ecological environment was declining.