武汉南湖湖区土地利用结构信息熵与湖泊形态变化分形分析

Fractal Analysis and Information Entropy of Land Use Structure for Lake Morphology in Urban Lake Area,Wuhan City

利用1996年～2006年武汉市1：1万土地利用数据库，结合1991年、1995年、2000年和2002年卫星遥感影像资料，借助系统论中的信息论思想，计算1996年～2006年10年间武汉南湖地区的土地利用结构信息熵和均衡度，并利用边界维数对南湖各时期的岸线形态变化进行定量判断。在此基础上，分析了武汉南湖土地利用结构信息熵和湖泊岸线分维变化之间的相互关系，并对土地利用结构信息熵和湖泊岸线分维在湖泊保护、管理规划方面的应用潜力做了初步探讨。结果表明，从1996年至2006年，南湖湖区土地利用结构的信息熵、均衡度以及岸线分维均出现逐渐减少的趋势，湖区土地利用类型向建设用地不断转变与湖泊人工填占是上述变化的主要原因，武汉城市化过程中人类活动大大加快了城市湖泊发展演化进程。土地利用结构熵、均衡度以及湖泊岸线分维从不同侧面反映了湖泊发展演化过程，能够为城市湖泊生态环境保护、管理规划提供有价值的参考信息，为进一步利用复杂性理论开展城市湖区经济、人口、资源协调发展等研究奠定了必要的基础。

The purpose of this paper is to analyze structure based on fractal theory. Nanhu Lake, in changes in lake morphology and urban lake land use Wuhan City, Hubei Province, was selected as the case study. First, a geospatial data set was constructed, including remote sensing images, regional maps, and 1 ： 10 000-scale land use data. In order to create lake morphology maps for 1996 - 2006, a Normalized Difference Water Index （NDWI） algorithm program was executed for each TM and ETM ＋ image. Next, the fractal dimension of Nanhu Lake in different years was calculated using GIS. We derived the changes in information entropy of the land use structure around Nanhu Lake from 1996 to 2006 using the land use data. Thus, a data sequence was obtained for comparative analysis. Results showed that there were significant shifts among the categories of cultivated land, water bodies and built-up land from 1996 to 2006 in the study area. Arable land was reduced by 11.56%, and water bodies were reduced by 22.17%. The proportion of built-up land increased from 28.71% to 66.72%. Most of the lost arable land and water bodies were converted into built-up land. The information entropy of the land use structure of the Nanhu Lake area decreased from 1.340 to 0.975, and the lake morphology fractal dimension decreased from 1. 334 to 1. 167. These changes in the study area have been driven by urbanization and industrialization, infrastructure growth and agricultural intensification. The rapid population and economic growth played an important role in land use changes around Nanhu Lake, and land use policy has had a definitive influence on land use change at different scales. In view of the importance of Urban lakes, some strategies and policies should be reoriented to attenuate the conflicts between the protection of cultivated land and ecosystems and socio-economic needs for expansion of built-up land. The information entropy of land use structure and fractal dimension are effective tools for analysis of land use change and lake morphology in urban lake areas, and can be applied for the purposes of urban lake protection and planning.