Measuring the Functional Compatibility of Land from the Perspective of Land-Use Mix: A Case Study of Xiangtan

Land-use mix is regarded as an effective method to improve urban quality and optimize built-up areas. In urban studies, this theory is usually defined in terms of diversity. Methodological approaches rely heavily on diversity in land use, but they often fail to consider functional compatibility as another critical characteristic, thus providing only a partial picture of land-use patterns. Although quantitative frameworks of land-use mix are mature and comprehensive, methods to measure functional compatibility are seldom discussed. Thus, by reviewing the literature on functional compatibility measurements, this paper proposes three new indices to gauge the degree of compatibility between land uses based on the quantitative approaches of social segregation. After considering existing methodologies, the paper first focuses on all land-use types, including undeveloped land, in order to capture hidden incompatibility; second, it considers all possible geo-features and includes them in the measurement process; and third, it attempts to interpret the functional compatibility of blocks and parcels of land to provide a basis for the district-level planning at scale of a block of land. To provide empirical evidence, this paper uses Xiangtan city as a case study—a typical medium-sized city in China, and representative of other third-tier cities—to evaluate the proposed indices. The general findings suggest that, overall, current land-use compatibility in Xiangtan is relatively good, but there are still some incompatibilities between neighboring lands. Most of the land has been developed for industrial purposes in a suburban industrial park. Industries, especially Class II industries, often generate pollutants such as noise, wastewater, and air pollution that have a huge negative environmental impact on the surrounding areas. These impacts can be effectively minimized through zoning and planning schemes that restrict industries to allocated areas, such as industrial parks or industrial zones. However, this is not always possible, partly due to the imperfect process of land acquisition that invalidates the intended benefits of planning schemes. Over time, the cumulative effect of these compromised planning schemes is an absence of scientific land-use management and a fragmented, complex, and incompatible pattern in land use. Based on the block-level indices we developed, we created a map of bivariate scatter plots for strategy making to improve the land-use mix in Xiangtan city through spatial planning