Abstract:

Multifunctional land use is an important way to improve land-use efficiency, alleviate the contradiction between people and land, and promote regional sustainable development. The Heihe River’s middle reaches in the middle of the Hexi Corridor, Gansu Province, China is the most densely populated and economically developed area, characterized by the most intense conflict between humans and land in the Heihe River Basin. However, the lack of knowledge about multifunctional land-use conditions hinders sustainable land-use planning and management in this area. In this study, we developed a land multi-function evaluation index system based on the production-life-ecology framework. We then applied a projection pursuit model based on a genetic algorithm to make a grid-based land multifunctional assessment at a 3 km×3 km resolution by assimilating geographical datasets from multiple sources, including remote sensing, socio-economic statistics, and point-of-interest (POI) data. To reveal the trade-offs and synergies of land multi-functions,we performed Spearman’s correlation and bivariate local spatial autocorrelation analysis. We also conducted a functional land zoning using RGB composite and clustering analysis. We found the following results: (1) The land functions in the study area varied with land-use patterns. The primary land function was for production, and the secondary land functions were for living and ecological functions. The land functions also showed spatial variability, characterized by the dominant production functions in the oasis agricultural lands, the useful living functions in the densely populated areas such as cities and towns with better facilities, and the most important ecological functions in Qilian Mountain and Longshou Mountain. (2) Land multi-functionality was enhanced during the study period. The spatial pattern of land multi-functionality and the dominant functions were stable, and the coordination among multiple functions was universally enhanced, indicating that various functions were more overlapped spatially. (3) On the basis of the principle of dominant use direction, the land in the Heihe River’s middle reaches can be divided into six zones: key development zones, optimizing development zones, moderate development zones, ecological barrier zones, ecological buffer zones, and ecological restoration zones. The former three zones were mainly used for agricultural production and urban space functions, whereas the latter three zones acted as ecological spaces. (4) There was still some room for improvement in land multi-functionality. Attention should be paid to non-dominant functions and the coordination of the inherent contradictions among functions. Efforts should be made to collaboratively promote ecological restoration and appreciation of natural capitalsand discover new growth points by constructing the regional pattern of lucid waters and lush mountains. This study highlights the POI data acquired from the Internet map open platforms. Compared with the conventional indicators, POI data can be updated more readily and can reflect the locations and types of facilities more accurately, capturing the levels of each land function more effectively. When making functional land zoning, this study also emphasizes using the RGB composite method to obtain dominant land functional patterns while simultaneously considering the cold and hot spots of land function and the trade-offs and synergies among functions. This approach reflected the current spatial pattern of land function clustering and the internal relationships among functions simultaneously, improving the classified zones’ accuracy and operationality.

Key words: land multi-function, multi-source geographic data, spatial-temporal pattern, trade-offs and synergies, land functional zoning, the middle reaches of the Heihe River