Evaluation of quality and spatial reconstruction of oasis rural settlements based on micro-scale

Abstract: Rural settlement space reconstruction is an important part of regional development and the key process of ecological civilization construction, and is one of the main means to solve the "Three Rural Issues" (agriculture, countryside and farmers) in China. The Silk Road Economic Belt and the 21st Maritime Silk Road Strategy have brought new opportunities for the Hexi Corridor, which is facing challenges in the sustainable development of rural settlements, and the spatial reconstruction has become one of the realistic problems that need to be solved urgently. Based on the 1 km × 1 km grid, this paper used quality evaluation model and gravity model to evaluate the quality of rural settlement in Shandan County, Gansu Province from 1998 to 2015, and analyzed the evolution of quality pattern. On this basis, the spatial reconstruction of rural settlements in oasis is realized at the microscopic scale. The results showed that: 1) The rural settlement area accounted for less than 0.1% of the total county area, but the area expanded rapidly, and the area between 1998 and 2008 increased by 38.99 hm2 with an average annual increase of 3.9 hm2. During 2008-2015, the area increased by 315.2 hm2 with an average annual increase of 52.53 hm2, which was faster than the previous period. The number and density of rural settlement patches increased, and the trend of spatial decentralization was obvious. The newly-formed settlements mainly include solo settlements and small settlements that are formed by several solo 290 settlements close to each other. The area of such small settlement is smaller than 1 hm2. In addition, some large settlements could be divided into smaller ones. These led to more solo and small settlements. 2) The spatial difference of quality of rural settlements was significant, which was closely related to the distribution of cultivated land and canal system, and there were significant "cultivated land directivity" and "canal directivity". After 2000, due to the expansion of the spatial range of cultivated land, the canal system increased, and the expansion speed of the two was significantly faster than that of the settlements. In 2008, 37.33% and 43.86% of the grid presented "cultivated land without settlements" and "canal system without settlements" phenomenon respectively. 3) The proportion of attractive area of Grade I in Shandan County is 24.04%, mainly in the grids of cultivated land without settlements and the grids of canal system without settlements. The proportion of attractive areas of Grade Ⅱ and Ⅲ is relatively small, which is 23.13%, and they are scattered in oasis. The number of attraction area of Grade IV is the largest, accounting for 52.82%, mainly distributed along the central oasis road and trunk canal system. 4) After the spatial reconstruction of rural settlements, the number of patches decreased from 3143 to 2269, and the patch density decreased; the number of micro-settlements and small settlements decreased and the number of medium-sized settlements increased, the saved land was 52.0 hm2 and the phenomenon of "dispersion, hollowing and chaos" in rural settlements had been improved to some extent. The reconstruction of oasis rural settlements based on the quality of oasis water and soil resources not only enhances the space efficiency of rural settlements but also enhances the man-land-water harmony of oasis rural settlements.