Research On Spatiotemporal Change Of Vegetation Cover In Guangzhou Baiyun Based On Remote Sensing And Geographic Information System

The nineteenth National People's Congress pointed out: to accelerate the reform of the ecological civilization system and to build a beautiful China.It is necessary to build an ecological corridor and carry out the action of land greening."Guangdong forest management advanced seminar" and planning documents also pointed out that we should further promote the new round of greening Guangdong action and build the first province of green ecology in China.The development goal of Guangzhou's urban master plan(2011 to 2020)is to enhance the charm of "Flower City","green city" and "water city",and create livable eco city.It is proposed that the construction of the ecological environment should be done at the same time in promoting the economic construction.However,as one of the fastest urbanization cities in China in recent decades,the vegetation coverage area of Guangzhou is facing great changes.There are a series of problems such as heat island effect,water pollution and air pollution.This poses a challenge to the construction of ecological civilization.This study is intended to qualitatively and quantitatively analyze the vegetation cover and the temporal and spatial variation of the heat island effect in the Baiyun District of Guangzhou.With the help of ENVI,eCognition,ArcGIS,IDRISI and other software,studied the response of spatial analysis and the classification,object oriented surface temperature inversion,CA-Markov model and ArcGIS statistical analysis methods covering extraction,spatial-temporal evolution,urban heat island effect,thermal environment on vegetation change and the changes between.The results are as follows:(1)In general,the vegetation coverage in the Baiyun District decreased slightly during the period of 8 years.Fell 0.97%,the woodland increased 3.25%,cultivated land and grassland decreased by 4.22%;the construction land increased by 5.17%,through the transfer matrix shows part of the increase is changed from cultivated land,water and other land types;spatial distribution,thanks to the policy of "Baiyun District garden city action plan,forest area increase,is different from the other city in the process of forest loss in the city trend.(2)Overall,the heat island effect in Baiyun District has been strengthened.The heat island effect in woodland and water covered area has not changed significantly,and the heat island effect in the other four land cover areas has been significantly enhanced.On 2008 the heat island effect,showing a small "rule,at the junction of Shijing street and Jiahe street,a large area is located in the southwest of the Huangshi street,new street,Tong King Street,Palit street,Pine Island street,Sanyuanli street,a small area is located in the north of Baiyun International airport.In 2016,the heat island effect spread significantly,showing a wide distribution.Besides woodland and water covered area,the heat island effect is significantly enhanced,and is consistent with the development direction of the city.The average temperature of the construction land is the highest,and the average temperature of the woodland is the lowest.The development of urbanization has led to the enhancement of the heat island effect;the woodland and the water body relieved the heat island effect.(3)The object oriented classification is an effective method for remote sensing image classification.The overall accuracy of the two-stage data is 89.58% and 88.89% respectively,and the classification accuracy is high.The classification of membership functions in fuzzy functions is adopted and hierarchy rules are established.The phenomenon of ground object confusion can be effectively avoided,and the situation of over segmentation and under segmentation can be effectively reduced.In terms of feature extraction,it effectively integrates spectral features,vegetation index characteristics and texture features into classification,and provides reference for TM image classification in other regions.(4)Based on the two period land use data,the CA-Markov model was used to predict the vegetation coverage in Baiyun District in 2024.It was concluded that under the natural development scenario,the construction land and woodland increased by 1.13% and 1.31% respectively,and water and arable land decreased by 2.28% and 1.21% respectively.It can be seen that the speed of urban development is slow in the future,and the urban greening is synchronized at the same time.The method based on RS and GIS proposed in this paper can effectively obtain information about the change of urban vegetation cover and the effect of heat island,and the results have obvious ecological significance.Therefore,this method is an effective method for the analysis of the spatial and temporal pattern of urban vegetation and the situation of the heat island effect.At the same time,it provides reference for urban planning and construction,guiding greening work,promoting livable cities and building "eco city".