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

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.