2000—2010年武汉市中心城区湖泊景观变化

武汉雅称"百湖之市",湖泊是武汉市的重要名片。以2000、2005和2010年三期Landsat TM数据为数据源,采用归一化差异水体指数(NDWI)提取湖泊水体信息,建立了各个时期武汉市中心城区湖泊矢量图层,计算了湖泊的面积萎缩率、斑块分维数和破碎度等景观指数,对2000—2010年武汉市中心城区湖泊变化特征进行了分析。研究表明,武汉市各个湖泊均有不同程度的萎缩,湖泊面积萎缩率大小和其所隶属的环线及政策因素有较大的关系;各湖泊斑块分维数在1-1.3之间,并越来越接近于1,表明在人类活动持续影响下,其形状变得越来越规则;同时斑块数目增加,湖泊在面积萎缩的同时,也变得越来越破碎,研究显示主要是道路修建所致导致的湖泊分割,湖泊被分割后,自净能力下降,会导致水体污染而最终被填埋。总之,10年武汉市湖泊景观环境朝着不良方向发展,应该制定更严格的政策进行水域管理。

Lakes evolution of central Wuhan during 2000 to 2010

Wetland is one of the three most valuable ecosystems in the world. Blessed with numerous lakes, Wuhan has enjoyed the reputation of "City with hundreds of lakes", and "Lake" is the important name card of Wuhan. Based on the Landsat TM images of the year of 2000, 2005, and 2010, we get the lakes variation characteristics from year 2000 to year 2010 of central Wuhan with the method of NDWI to extract prominent information of lakes and then create the vector layers of the lakes data of the three years, which are used to calculate the Shrinking Rate of the lakes, fractal dimension of lake patches and the degree of fragmentation of lake landscape. The study shows that: (1) All the lakes have shrunk, and there are different shrinking rates of different lakes, which are mainly decided by which loop are these lakes in and policy factors. (2) fractal dimensions of these lake patches are range from 1 to 1.3, and are increasingly close to 1. It shows that the lakes are becoming regularly shaped under human activity influence. (3) There is an increase in the number of lake patches. With their decrease in area, the lakes become fragmented at the same time due to the traffic construction. When a lake is fragmented, it is easier to be polluted for the reduction of its self-purification capacity and probably to be filled in at last. In one word, the landscape environment of lakes proceeds in a negative direction. Stricter policies should be put forward for administration and protection of the lakes of Wuhan City.