重庆市农村居民点分形特征及影响因素分析

Analysis on fractal characteristics of rural settlements in Chongqing and its influencing factors

农村居民点的分形特征能很好地反映其空间占据能力。该文选取浅丘平坝区、低山丘陵区、中山丘陵区、高海拔山区4种典型生态类型区,应用分形几何原理,分析了不同生态类型区农村居民点的分形特征,探讨了不同生态类型区分形特征的主要影响因素。结果表明:不同生态类型区的农村居民点分形特征存在差别,主要受高程、坡度、农民人均纯收入、水系、交通等因素的影响。其中浅丘平坝区分维数值最高1.63,高海拔山区分维数值最低1.47,4种生态类型区的农村居民点分维数值明显高于交通和水系的分维数值,但随着农村交通体系的完善,其对农村居民点分形特征的影响会增加;坡度对不同生态类型区农村居民点分形特征的影响是一致的,分维数值均随着坡度的增加呈现先增加后减少趋势;农民人均纯收入高的生态类型区农村居民点分维数值更高;4种生态类型区的农村居民点分维数值在短期内表现出下降或平稳趋势,但从长远来看,随着经济社会的发展和各种城镇化建设政策的落实,4种生态类型区的农村居民点分维数值均呈上升趋势,其边界曲折度不断减小,其形态逐步向规则化发展,但受地理位置和社会经济条件的限制,其上升的趋势会存在差异。该研究可为丘陵山区的农村居民点整理、布局优化提供参考依据。

The spatial distribution and variation of rural settlement can be well presented by the fractal characteristics of rural settlement. This paper investigated the spatial variation of rural settlement and its influencing factors using fractal dimension in four typical ecological zones：shallow hilly region, low altitude hilly region, Three Gorges reservoir area and high altitude mountain region in Chongqing, China. The fundamental data including the rural settlement, hydrology, transportation, elevation and slope were extracted and processed using Arcgis 10.0 GIS software, and the sensor data including economy, population, and living space per capita were collected from the China Statistical Yearbook. The fractal dimension of rural settlement, drainage and transportation were calculated using Matlab. Differences of fractal dimension of the rural settlement were observed among four regions, which were mainly contributed by elevation, slope, per capita annual net income of farmers, drainage and transportation. The highest fractal dimension （1.63） of the rural settlement was presented in the shallow hilly region, while the lowest （1.47） in the high altitude mountain region. The rural settlement had higher fractal dimension than the transportation and drainage. It was distributed mainly in the area with the elevation〈800 m, and clustered mainly in the area where the elevation varied between 300 and 500 m. The highest fractal dimension （1.5） of the shallow hilly region was presented in the area where the elevation varied between 300 and 500 m, while those of the low altitude hilly and high altitude mountain region were observed in the areas with elevation varied between 500 and 800 m with the corresponding fractal dimension of 1.48, and 1.37, respectively. The fractal dimension of the rural settlement showed similar changing patterns in the same slope belt. The highest fractal dimension were presented in two slope belts where the rural settlements were distributed mainly with the slope of the two belts varying between 6°and 15°, and between 15°and 25°, respectively. Fractal dimension of the rural settlement was positively related with per capita annual net income of farmers. High fractal dimension was observed in the ecological area with high per capita annual net income of farmers. Negatively correlation of fractal dimension was observed between rural settlements and population. The fractal dimension of the rural settlement showed decreasing or steady trends in a short period, while it would increase in a long period as the development of economy and society, and the implementation of urbanization policies. The boundary tortuosity of the rural settlements tended to decline because of the boundary shape of settlements becoming more regular, but the change rate of fractal dimension of the four ecological regions won’t be the same because of the restraint of location and economy. The findings in this work would facilitate the practical applications in rural residential consolidation and layout planning in similar regions.