| Urban wetland refers to the artificial or half artificial or natural wetland remained in the construction of the city,which differs from natural wetland in many aspects,such as bionomics property,landscape pattern,functional service.This thesis will take the urban wetland of Changsha as the research object.Under the support of GIS using decision tree to classify remote sensing image data of Changsha city in 2001,2009,2013.Then the author will quantitatively analyze the types of wetland and the changing trend of each landscape index in different times through the analysis of the landscape pattern software FRAGSTATS 4.2.At last,this paper will use some functional module of the spatial analysis software: IDRISI to predict and analyze the distribution of urban wetland landscape comprehensively.According to the research,some problems are as follows:This paper will choose the Landsat TM and ETM+ remote-sensing image of Changsha urban area in 2001,2009 and 2013 as the basic data.ENVI 5.1,Arc GIS 10.1 platform and some theory of landscape ecology will also be used to parse those three years' satellite photograph data and its type change.At the same time,based on the parsed data,1)River accounts for the largest in the overall distribution of Changsha urban wetland type,up to 40.67%.So the change of its quality has effected the whole urban wetland.The proportion of urban lake first decreased then increased.It was accounted for 6.52%,5.19% and 6.96% in 2001,2009 and 2013 respectively.The planning and development of artificial wetland park is the main reason of this.While ponds,swamps,and paddy fields of wetland landscape proportion showed a trend of decline each year.The main wetland landscapes of Changsha are some gathered wetland parks with big size and some other wetland landscapes are scattered.The poor connectivity of each gathered wetland patches and the degradation of those scattered wetland landscape will lead to the urban landscape fragmentation and even worse.2)Through the analysis of Changsha's landscape index,this thesis finds that the planning of Changsha's urban wetland presents a situation: construction is before the governance.Wetland fragmentation degree is most serious in 2009,its fractal dimension is up to the maximum: 1.778,plaque index and shape index also up to the maximum,which means the wetland landscape patterns in 2009 are very scattered,its fragmentation degree are also very high,and the boundary of wetland is complicated.Many landscape patches gathered in some areas along with the increased wetland protection and artificial wetland investment in recent years.According to the comprehensively analysis to the wetland landscape index,the main urban wetland landscape of Changsha is rivers,then it comes to paddy fields and swamps,the proportion of lakes and ponds are the lowest.The fragmentation degree of ponds swamps and paddy fields are worse than others.Swamp landscapes mainly attach to those highly clustered landscape patches such as river and lake.3)Based on the prediction landscape of CA-Markov,paddy fields around the urban area will be occupied by other land use types and this phenomenon is getting worse,the reduction of paddy fields accounts for 24.10%.Lakes and reservoirs and swamps in the center of the city become the main rallying point of Changsha's urban landscape pattern.With the protective exploitation and the increased investment,its percentage increased to over 33%.While the scattered ponds started to decay because it's small footprint and highly fragmentation.Through the research of Changsha's urban wetland landscape patterns distribution characteristics and the predictive landscape distribution,the development between the expanding urbanization and the wetland landscape protection is inharmonious.The wetland of peri-urban areas decrease a lot and the wetland landscape in the center of the city gathered and broken at the same time.The author has three suggestions to solve those problems.First,coordinate the development of the entire area and the planning and design of wetland.Second,protect the small landscape like city pool to maintain the integrity of wetland landscape type,and strengthen the continuity between the landscapes.Third,increasing investment to expand the urban lake landscape planning such as artificial wetland park,strengthen the continuity of extra surrounding landscape,and improve fragmentation phenomenon.The optimization design of Changsha's urban wetland landscape provides new application and data support for the dynamic change of wetland landscape index,gives a summary description for the reason why its wetland landscape pattern change.At last,this paper predicts the change of urban wetland landscape distribution through model and offers some meaningful and practical suggestions... |
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