Evolution of Port Ecological Carrying Capacity Based on SD Model

Construction of ecological port has become an important direction of port development. Research on evaluation and prediction of evolution of port ecological carrying capacity trend can provide available and reliable method for ecological port construction. A system dynamics (SD) model for port ecological carrying capacity considering characteristics of port ecosystem is built in this paper, based on causal feedback analysis with aspects of socio-economic, resources and environment. The proposed model could simulate the process of port ecosystem evolution and evaluate the dynamic condition of port ecological carrying capacity with the supply-demand balance index of the ecological carrying capacity. In the model, GDP growth rate, investment proportion of environmental protection, comprehensive energy consumption per unit throughput, water consumption per unit of throughput, COD generation per unit of throughput, SO2 generation per unit of throughput, solid waste generation per unit of throughput are selected as control variables. The proposed model is utilized to forecast the trend of evolution of port ecological carrying capacity from 2015 to 2030 in a case study of a port area of Dalian Port with regard to three port development scenarios, respectively natural development scenario, coordinated development scenario and environmental protection scenario. The results show that energy consumption is an important bottleneck restricting the improvement of the port ecological carrying capacity, in this sense that optimization of energy structure harbor and strengthening energy management contribute to improve port ecological carrying capacity, and coordinated development scenario is the optimal way to achieve the sustainable development of port ecosystem. This paper can provide a theoretical basis for the construction of eco-Port.