Study On The Changes Of The Lake Landscape Of Changsha Under The Background Of Rapid Urbanization

With the rapid development of economic society and the rapid advance of urbanization,the scale of urban construction land is accelerating its extraordinary expansion,and the ecological lands,such as the lakes inside and surrounding the town are being occupied by the construction,resulting in the shrinking of lakes and the aggravating of fragmentation,so that the lake landscape changes greatly.Analyzing the spatio-temporal variation characteristics of the lake landscape and the spatio-temporal correlation with the level of urbanization has a certain theoretical significance for enriching the research content of lake landscape.At the same time,it also provides realistic basis for the protection,development and utilization of the lake.This study chose Changsha city,which is a rapidly urbanized city in recent years,as the research object,and the valid time of the study from2002 to 2014 as the research time range.The image data was downloaded from the Remote Sensing and Digital Earth Chinese Academy of Sciences and the GS CLOUD,and used ENVI5.1 to do data pre-processing.On this basis,ArcGIS10.0 was utilized to interpret the pretreatment remote sensing image data,and to extract the lake data.And then it used Fragstats4.2 landscape software to calculate the landscape index of different years and analyzed the spatio-temporal variation characteristicsof each index.Meanwhile,after collecting the data of land use change and the socio-economic data of Changsha during the research period,this study analyzed the spatio-temporal correlation of the lake landscape index of Changsha city and the main urbanization index by using the Canonical correlation model of SPSS22.0 software.Results show that:(1)Between 2002 and 2014,with the acceleration of urbanization,the overall performance of Changsha lake landscape changes are that the CA,NP,PD and SPLIT had big changes,while the changes of DIVISION,FRAC,AI,SHAPE-MN were relatively small.Among them,the SPLIT and AI were on the rise,while the CA,NP,PD,FRAC and SHAPE-MN presented downtrend.(2)In 2014,Ningxiang County,Liuyang city,Changsha County and Wangcheng District,had a big CA with a large number of plaques and a smaller PD;the SHAPE-MN?DIVISION?FRAC?SPLIT were higher,while the AI was lower.On the contrary,in Yuelu District,Furong District,Yuhua District,Kaifu District and Tianxin District,the CA was small with a small number of plaques,a lower SHAPE-MN?FRAC and a higher DIVISION;Yuhua District had a smaller PD,a higher SPLIT and a lower AI;Yuelu District,Furong District,Kaifu District and Tianxin District presented a bigger PD,a lower SPLIT and a higher AI.(3)From 2002 to 2014,in Kaifu District,Yuelu District,Furong District,Tianxin District,Yuhua District,and Wangcheng District,the CA?NP?SPLIT had a great change,including the decrease of CA?NP and the rise of SPLIT.The CA of Changsha County increased more,and the change of SPLIT and DIVISION was bigger,showing a downward trend;while the change of the landscape index of Ningxiang County and Liuyang city was relatively small.(4)From 2002 to 2014,the urbanization of Changsha city maintained rapid growth year by year,and the corresponding lake landscape index also changed,on the whole,demonstrating a certain degree of regularity.Their relativity about time order was high.The CA?DIVISION showed a trend of decline in general,but the changing trend was just the opposite,which led to the high negative correlation between the CA?DIVISION and the typical variables of the urbanization index.With the acceleration of urbanization,NP ? PD ? SPLIT ? FRAC ?SHAPE-MN?AI changed over time without certain regularity,showing a relativlely lower correlation with the comprehensive variables of the urbanization index.(5)In 2014,the urbanization level,the lake landscape index of each county and district of Changsha city showed some correspondence in space,with a high spatially correlated correlation.AI had the highest correlation with the comprehensive variables of the urbanization index,followed by SHAPE-MN.The correlation between FRAC?NP?PD?CA and typical variables of Urbanization was medium;while the correlationbetween the DIVISON and typical variables of Urbanization was the lowest.(6)As the CA of the lake landscape was declining,NP reducing,and SPLIT deepening,this study proposed some optimization countermeasures,such as delimiting the Lake nature reserve,strengthening the protection of the lake watersape and improving the overall fragmentation pattern of lake landscape In the future.