Research On Land Cover Change And Evaluation Of Ecological Environment Quality

There is a plan to build a modern international "Humanitarian Green City" and a national ecological civilization construction demonstration zone by 2020 in Nanjing.The degree of urbanization is high in Nanjing,which causes land structure changes.Especially the unreasonable expansion of cities and suburbs may lead to a series of ecological and environmental problems.A study on land cover change and ecological environment quality in Nanjing may be helpful to carry on land use planning according to the dynamic changes and balance economic development and ecological protection.In this paper,the Nanjing city is selected as the study area.Multi-source fusion data at high spatiotemporal resolution are acquired by applying the Spatial and Temporal Adaptive Reflectance Fusion Model(STARFM).Land cover classification results in Nanjing from 2000 to 2018 are classified based on Classification and Regression Trees(CART).Then land cover change is analyzed respectively from the perspective of structure,time and space.The ecological environment quality in Nanjing from 2000 to 2018 is evaluated by using Remote Sensing Based Ecological Index(RSEI).The results of the paper are as follows:(1)It is feasible to replace traditional single-source data with fused multi-source data.The Landsat data and MODIS data are fused by the STARFM method at the pixel level.High spatiotemporal resolution simulated images for 2000,2005,2010,2014 and 2018 are obtained.Comparing the simulated image with the real Landsat image in the same year,it can be seen that the spatial distribution and object features of the two images are similar.The absolute average error is low,and the correlation coefficient is high.(2)The land cover change in Nanjing from 2000 to 2018 is analyzed.Cultivated land is the largest type of land.The forest and grassland are the second-largest types of land in 2000,2005 and 2014.The construction land is the second-largest type of land in 2010 and 2018.The water area and unused land are the smallest types of land.The area transferred into the construction land and the area transferred from cultivated land are largest from 2000 to 2005,while the largest change of type from 2005 to 2018 is the cultivated land.The most spatial distribution of the forest and grassland is not changed.The cultivated land reduces sharply in the suburbs and the south,and it reduces slightly along the Yangtze River.The construction land increases slowly in the core urban areas,and it increases quickly in the south.(3)The ecological environment quality in Nanjing from 2000 to 2018 is evaluated.In general,the environment is better according to the distribution and changes in the ecological environment grades.From 2000 to 2018,the area with a “good” level continues to rise,and the area with a “poor” level continues to decline.Over 90% area of the city meets the qualification except the years 2000 and 2014.In most areas,the level of ecological environment quality maintains or improves slightly.While,in a small part of the city,the level decreases slightly.