Optimizing spatial coordination layout between town and agriculture using PLUS spatial decision model

Agricultural and urban space can dominate the national food security and the sustainable development of cities and towns. This study aims to treat the ever-increasingly serious contradiction between urban and agricultural space. A case study was selected as the Nankang District, Ganzhou City, Jiangxi Province of China. Four steps were carried out, including land suitability evaluation, spatial prediction and correction, spatial conflict coordination, as well as scheme determination and optimization. Specifically, the entropy weight and weighted sum were used to quantify the indicators, and then determine the weights for the more accurate evaluation of cultivated and construction land. GIS technology was also applied to evaluate the suitability of cultivated and construction land. PLUS and convex hull models were then introduced to predict the scope and types of urban expansion. The accuracy of urban boundary delineation was finally improved to optimize the layout of permanent basic farmland and urban boundaries. The results show that: 1) The cultivated land with the high comprehensive quality was concentrated mainly in Tangjiang, Jingba, and Fenggang Town. The comprehensive score was ranked in the descending distribution of the central city to the surrounding towns and villages after the suitability evaluation of construction and development. The highest scores were found in Dongshan and Rongjiang Streets. 2) The PLUS model predicted that the newly-built construction land would be 3362.85 hm² by 2035 (including urban construction land of 2023.06 hm²). The convex shell model presented that the extension type was dominant in the future, where the Rongjiang and Dongshan Streets were the key areas for the urban expansion and development. 3) The cultivated land was introduced for national use after the evaluation of the suitability of the comprehensive quality. The agricultural space was divided into protected areas, reserve areas, and general cultivated land, according to the national average utilization of cultivated land. Once there was a spatial conflict between urban development boundaries and protected areas, the urban development boundaries were adjusted to give priority to the protection of cultivated land. When there was a spatial conflict between the urban development boundary, the reserve area and the general cultivated land, the farmland was transferred for the urban development. The final designated area of urban development boundary and permanent basic farmland were 8895.67, and 23368.76 hm², respectively. The average quality of the designated permanent basic farmland was higher than that in 2017, indicating accurate coordination and optimization. The findings can provide a strong reference for the protection of cultivated land resources, as well as the optimization and coordination of permanent basic farmland and urban boundaries.