Distribution pattern characteristic and type classification of rural settlements in loess hilly-gully region

Abstract: Rural settlements constitute the spatial area of region's production, livelihood and ecology. Therefore, it is necessary to study rural settlements' spatial distribution pattern for optimizing the town-villages construction pattern. In this paper, we aimed to improve the microcosmic study of rural settlements and provided theoretical support for the construction of new harmonioussocial society in the countryside. Based on the Google earth satellite images of Baota District in Yanan city in 2015, we obtained the rural settlements feature, arable land feature, road feature, and the river feature after geometric correction, coordinate registration, visual interpretation and vectorization. Then we conducted a quantitative analysis of the rural settlements' spatial distribution differentiation in Baota District using exploratory spatial data analysis model and geography grids analysis method, and identified the regional types basing on multi-dimensional characteristics. The results showedthat, 1) in the spatial distribution aspect, rural settlements in Baota District were characterized by obvious cluster spatial distribution mode, which was shown in the variable density of rural settlements. The density of rural settlements in northern area was higher than that in southern area, and the density higher than five per square kilometers mainly distributed in the north area of Qiaogou town and Chuankou town. In the scale aspect, rural settlements in Baota District showed an obvious spatial cluster distribution mode, and were in a "Y" structure. In the location aspect, rural settlements presented a normal distribution pattern along with the variations of elevation and slope. In the shape aspect, rural settlements had a low complexity in shape and most were stripe type. The shape index was also infected by the road level. The high shape index value distributed along the national level road and provincial level road, the low shape index value distributed along the lower level road; 2) the location of rural settlements closely related to the transportation, 81.42% of the rural settlements were approaching the main road less than 500m. And the location of rural settlements was also affected by the arable land, 59.7% of the rural settlements' farming radius distributed between 700 and 800 meters; 3) the characteristics of the rural settlements distribution pattern in the typical ditch area were influenced by the topographic factors, and the variation of rural settlements scale showed a multi-center characteristic. The distribution pattern of the rural settlements along the National HighwayNo. 210 was greatly affected by economic factors; and 4) based on the multidimensional feature combination matrix, the rural settlements were divided into nine types. The small scale-disadvantage location-aggregation distribution and small scale-disadvantage location-discrete distribution were the main problem areas. The spatial optimization of town-village was a complex and systematic engineering, and it was the first step to analyze the spatial distribution pattern of different area for rural settlements remediation and town-village spatial structure optimization. These results showed that rural settlements optimization should be based on different types, according to local conditions, and the main problem area should be the priority; the multi-center and equidistant distribution characteristics of gully settlements could be used to guide the rural settlements optimization and protect the security of ecology.