基于PLUS空间决策模型的城镇与农业空间协调布局优化

正确处理好农业空间与城镇空间之间的矛盾,对保障国家粮食安全、促进城镇可持续发展具有重要意义。该研究以江西省赣州市南康区为例,应用GIS技术,在耕地与建设用地适宜性评价的基础上,引入PLUS模型、凸壳模型预测城市扩张范围及类型,初步划定城镇开发边界与永久基本农田布局,并根据城市发展规律和冲突矛盾协调原则,对永久基本农田和城镇开发边界进行优化。结果表明：1）南康区综合质量高的耕地主要集中于唐江镇、镜坝镇、凤岗镇等乡镇;建设开发适宜性评价综合得分由高到低呈现出中心城区向四周乡镇圈层式扩散的分布情况,东山街道、蓉江街道的分值最高。2）PLUS模型预测至2035年南康区新增建设用地为3362.85 hm²（其中城镇建设用地2023.06 hm²）,凸壳模型得出南康区扩张类型属于外延型,蓉江街道和东山街道是未来城区扩张发展的重点区域。3）以耕地国家利用等平均值为标准,将农业空间划分为保护区、储备区与一般耕地,当城镇开发边界与保护区发生空间冲突时,调整城镇开发边界,优先保护农田;当城镇开发边界与储备区、一般耕地发生空间冲突时,调出农田,保障城镇发展。研究结果可为耕地资源保护提供参考,为永久基本农田与城镇开发边界优化协调提供借鉴。

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.