渭北台塬县级城市空间扩张的分形研究

Fractal Study of County-level Cities in Weibei Platform Region

基于RS与GIS技术,采用分形理论对渭北台塬县级城市空间扩张特征进行分析。结果表明:1990—2010年台塬区县级城市加速扩张,总面积扩大了2.86倍,年均增长率达8.7%。1990,2000,2010年县级城市空间形态分维值均值分别为1.08,1.09,1.21,变异系数分别为3.06,3.09,3.93,城市空间形态总体简单但渐趋复杂且不断分化。异速生长模型标度因子b值均小于1,人均城市空间较为合理但远未达到最优状态。1990—2000年城市以填充型扩张为主,2000—2010年以外延型扩张为主,用地集约性呈下降趋势。空间上,铜川塬、宝鸡塬扩张较快,人地关系较差;咸阳塬扩张最快,人地关系一般;渭南塬扩张相对较慢,人地关系较优。总体上,亟待加强城市规划以构建节约型城市空间增长模式。

This paper took the method of fractal dimension of space graphics,analyzed the county-level town expansion characteristics in the Weibei platform region based on GIS and RS. The results as the follows： The area of the counties expanding were accelerating from 1990 to 2010 with an average rate of 8. 7%,the built-up area in2010 up to 2. 86 times in 1990. The shape of the cities was simple,however,it became complicated continually.The average fractal dimension value of the cities was 1. 08,1. 09,and 1. 21 in 1990,2000 and 2010 respectively.And the variation coefficient of the fractal dimension were 3. 06,3. 09 and 3. 93 in 1990,2000 and 2010 respectively. The scale factor ＂ b ＂of allometric growth model was less than 1,per capita urban space is reasonable,but it is still far away from the optimal state. At spatial,the cities in Tongchuan and Baoji platform region were expanding faster,and its human-earth relation was worse. However,the cities in Xianyang platform region were expanding fastest,and its human-earth relation was general. The cities in Weinan platform region were expanding slower and its human-earth relation was better.