Sustainable port cities with coupling coordination and environmental efficiency

Abstract Ports are an essential impetus for the development of cities, and cities provide important resources and infrastructure for ports. As a significant factor to enhance the competitiveness of port cities, the sustainable ability affects the development characteristics of cities. How to evaluate the sustainability has become the priority of port cities development. However, existing researches mainly focus on ports or cities separately, instead of combining the two. Therefore, we first establish a two-stage interaction model to associate port and city. Then we propose a new index system, covering the economic, environmental, and social indicators. Based on the evaluation framework, we adopt the directional distance function based on the slack-based measure model (SBM-DDF) and the coupling coordination degree (CCD) to measure the sustainability of port cities from the perspective of external influence and internal interaction. We select nine port cities in China as research objects. The results display their relative differences in sustainability. Hong Kong performs the best, while Xiamen performs the worst. According to the experience of Hong Kong, this paper puts forward corresponding improvement measures aiming at the disadvantage of port cities in order to achieve better sustainable development.