50年来太湖水网地区城市化空间过程的监测与模拟 Ⅰ宜兴城区城市用地扩展的遥感监测

MONITORING AND MODELING THE SPATIAL PROCESS OF URBAN EXPANSION IN TAIHU LAKE AREA,CHINA IN THE LAST 50 YEARS Ⅰ. A CASE STUDY OF YIXING CITY ON MONITORING OF URBAN EXPANSION

长期以来,由于历史数据的缺乏,很难获得解放后我国城市扩展的完整过程。本研究在遥感、地理信息系统技术支持下,采用7个时期的航空图片和卫星数据,分别对宜兴市194 9、196 6、1981、1984、1992、1996和2 0 0 0年的城区范围和耕地被占用情况进行监测。结果表明,5 0多年来宜兴城区面积从1 5km2 扩展到13 5km2 ,翻了3番多;城市扩展过程呈现两个阶段,即194 9～1984年的缓慢扩展阶段和1985～2 0 0 0年的快速扩展阶段,前一阶段年均扩展速度仅3% ,而后一阶段年均扩展速度达到2 1% ;各个时期城市扩展占用的土地中90 %以上是高质量的耕地,表明城市扩展成为耕地流失的主要因素之一。相关分析显示,城市扩展与工业发展关系最密切,工业发展为城区扩展提供了动力,而城区面积与第三产业比重的相关系数在三个产业中是最高的,表明宜兴城区成为该县第三产业的主要聚集地。从空间扩展过程来看,宜兴城区1984年以前沿着老城区零散填充式扩展,此后沿着公路快速扩展,并逐渐呈块状填充式扩展。由于宜兴处于苏南水网发达地区,水系严重制约了城市扩展的方向。

Remotely sensed images and historical aerial photographs at seven different periods are used to study urban expansion in Yixing city, in the Taihu Lake region, East China in the last 50 years. The results show that the urban area of Yixing expanded by more than 8 times, and the annual expanding rate was only 3% before 1984, and 21% from 1984～2000. Within each period more than 90% of the expanded area is cropland. The expansion was characterized differently from period to period. Before 1984 the urban area expanded separately along the old city boundary, after that the city began to expand along main roads and highways, and then filled in the empty blocks between the roads. The urban development is also confined by river systems, which is a representative characteristics of urban expansion in the Taihu Lake region in China.