城市湖泊地区的土地利用变化--以武汉东湖为例

利用1986、1993、1999年的Landsat TM卫星遥感影像和1981年地形图，借助GIS技术分析了城市湖泊地区—武汉东湖流域1987～1999间土地利用的时空变化及景观结构的变化。土地利用分为水体、针叶林、阔叶林、灌草、裸地、农业用地和城镇用地七种类型。各时期遥感影像分类精度都在85%以上。该流域土地利用变化以城镇大幅度扩展（从占全流域面积的9.1％到29.6％）、农业用地增加(从7.0％到13.9％)和由此引起的林地（从占全流域面积的33.6％到24.3％）、水体（从30.4％到23.8％）面积减少为主要特征。同时流域整体的景观多样性下降、优势度提高，但不同景观组分的碎裂化程度的变化趋势不同。其中，城镇用地等优势景观组分的分布趋于聚集，其他类型多趋于碎裂化。流域的城市化具有方向性。城市的快速扩展对林地、灌草、水体等城市湖泊地区的自然生态系统产生显著影响。流域的土地利用及变化受多种自然、社会因素影响。

LAND USE CHANGE IN URBAN LAKE WATERSHED--A CASE STUDY AT DONGHU LAKE, WUHAN

Using Landsat TM imageries (taken in 1987, 1993 and 1999) and GIS method, the spatial and temporal changes in land use of a typical urban lake watershed, Donghu Lake of Wuhan, were analyzed between 1987 and 1999. The satellite images were classified into seven land use/cover categories: water body, broadleaf forest, coniferous forest, shrub-grass land, bare land, cropland and urban land. Overall classification accuracy on satellite imagery for three period was all above 85%. Our results showed that urban land expansion (from 9.1% to 29.6% of study area) and farmland increase (from 7.0% to 13.9%), at the cost of reduction of water body (from 30.4% to 23.8%) and forestland (from 33.6% to 24.3%), are main characteristics of land use change in the watershed. At the same time, landscape diversity of the watershed decreased, as dominance increased during the study period. While degree of fragmentation changed differently between dominant landscape components and others. Because forestland becomes major source of the increment of the urban land and farmland, the ecological impact of urbanization on this urban lake watershed is remarkable. Several physical and economical factors contribute to land use pattern and its change in the study area.