Remote Sensing Evaluation On Ecological Environment In Pearl River Delta City Cluster

With the comprehensive progress of urbanization,ecological environment problems such as land desertification,reduction of vegetation resources,drought and flood disasters and haze have become increasingly prominent,which have seriously threatened the sustainable development of human beings.As an important economic center region and a key protection area of ecological environment,the Pearl River Delta(PRD)city cluster,a leading area of China’s reform and opening up,has undergone great changes in land use,increased proportion of construction land,and the ecological environment has been affected to varying degrees.With the emergence of negative environmental effects,the state attaches great importance to the construction of ecological civilization.In the report of the Nineteenth National Congress,General Secretary Xi pointed out that we should speed up the reform of ecological civilization system and build a beautiful China.Therefore,comprehensive evaluation and analysis of the ecological environment of the PRD city cluster and its changes is an important basis for formulating ecological environment protection countermeasures.The article based on the PRD city cluster as the research area,in 2006 and 2016 Landsat remote sensing satellite image data as the main source of information,supported by RS,GIS and GPS,with ecological index(EI)method and remote sensing ecological index(RSEI)method on the PRD city cluster of 2006 and 2016 respectively to evaluate the ecological environment situation,comparing the results of the two methods.The results show that the EI method is consistent with the RSEI method for the assessment of the ecological environment of the PRD city cluster.The RSEI method can be used to analyze the ecological environment of the PRD city cluster.It selected four indicators of greenness(NDVI),humidity(WET),dryness(NDSI)and heat(LST),used principal component analysis method to determine the weight of the indicators,calculated the RSEI of the PRD city cluster,and divided the RSEI into five grades: excellent,good,medium,low and bad,with the analysis of the ecological environment evaluation of the PRD city cluster and the change of ecological environment in 2006-2016.The main conclusions are as follows:(1)It is feasible to analyze and evaluate the ecological environment of the PRD city cluster by RSEI method.Compared with EI method,RSEI method also has accuracy and objectivity.The visualization of its evaluation results is helpful to analyze the dynamic changes of ecological environment in the PRD city cluster.(2)The increase of NDVI and WET is a key factor affecting the ecological environment of the PRD city cluster.The increase of NDSI and LST has a negative effect on the ecological environment.Humidity had a great influence on the ecological environment of the PRD city cluster in 2006,while greenness had a great influence in 2016.(3)In 2006,the RSEI value of the PRD city cluster was 0.652;in 2016,the RSEI value was increased to 0.769,and the ecological environment was improved.The city cluster with better ecological environment include Zhaoqing,Foshan,Jiangmen,Huizhou,Dongguan,Zhongshan and Zhuhai.With stable ecological environment are Shenzhen and Guangzhou.(4)In 2006,the ecological environment of the PRD city cluster was mainly good,and in 2016,the ecological environment of the PRD city cluster was mainly good and excellent.The good ecological environment is mainly concentrated in the mountainous area of the city cluster.The poor ecological environment is mainly distributed in the central part of the city cluster,and the areas with rapid economic development and dense population.(5)From 2006 to 2016,the ecological environment of the PRD city cluster has been improved as a whole.Among them,48.71% of the ecological environment improved,Foshan,Huizhou and Jiangmen achieved the most significant results;44.87% of the ecological environment remained unchanged;6.42% of the ecological environment became worse.