Analysis On Dynamic Change Of Land Use Pattern Around Chaohu Lake

Chaohu Lake is one of the five largest freshwater lakes in China.Due to the development of industrial and agricultural production and urban construction,the pollution of Chaohu Lake is relatively serious.Since Chaohu was included in Hefei City in 2011,Hefei City has increased pollution and environmental remediation in the Chaohu Lake Basin,returning farmland to forests and reducing wetness,and reducing non-point source pollution.In order to understand the returning farmland to forest project,especially the land use type and its pattern change around the Chaohu Lake since the integration of Chaohu Lake into Hefei City.This paper takes the remote sensing image data of the surrounding watershed of 3km around the Chaohu Lake water source protection area in 2002,2009,2012 and 2016 as the data source,combined with RS and GIS technology,and carries out remote sensing classification of land use types to analyze the 3km range around the surrounding Chaohu Lake in different years.The dynamic changes of land use types and their patterns provide a scientific basis for objective evaluation of land environmental improvement effects and land planning adjustment around the Chaohu Lake.The main achievements of this paper are as follows:(1)From 2002 to 2009,he area of woodland,arable land and grassland around Chaohu Lake showed a decreasing trend,accompanied by large-scale expansion of construction land and a small increase of water area.By 2009-2012,the area of surrounding water was basically the same as in previous years,while the area of cultivated land and grassland was still decreasing,and the corresponding increase was the area of construction land and forest land.From 2012 to 2016,the evolution characteristics of land use types around Chaohu Lake are basically the same as those in the previous stage.(2)In 2002,2009,2012 and 2016,the dominant land use types around Chaohu Lake include cultivated land,forest land and construction land.Among them,forest land and construction land change range is larger,the maximum can be increased to 5.3%and 7.2%respectively.The change of cultivated land and bare land use remained relatively stable,mostly at 1%.The change of unused land and water area is small,which has no effect on the result analysis.In addition,the reduction of grassland and unused land is mainly transferred by cultivated land,forest land and construction land,while the transfer of construction land and water area is relatively insignificant.(3)The research about the dynamic pattern of land use around Chaohu Lake shows that the land use conversion around Chaohu Lake is obvious in the past 15 years.It is the most obvious and rapid change in 2009-2012.Because Chaohu Lake was initially classified into Hefei Administrative Region,the degree of fragmentation of landscape pattern is relatively high.During the period of 2012-2016,the evolution of land pattern accelerated,but due to the regulation and control of policies,it gradually became reasonable,but the construction land further expanded and amalgamated to form a complete urban landscape area.(4)The driving forces of land use pattern evolution around Chaohu Lake are analyzed and summarized.It is mainly manifested in natural factors such as climate conditions,as well as social factors such as population growth,macro-policy and urban planning concept of sustainable development.