Sustainable Urbanization Synergy Degree Measures—A Case Study in Henan Province, China

Sustainable urbanization emphasizes properly handling the relationships between people, people and society, and people and nature in the process of urban development. However, sometimes these interactions are difficult to quantify. Through an analysis of the structure and functions of the sustainable urbanization system, this paper introduced synergetic theory and constructed a sustainable urbanization synergy system (SUSS) with five subsystems; demographic change, economic development, spatial structure, environmental quality, and social development; to study the synergistic development and orderly evolution trend of the sustainable urbanization composite system. Using sustainable urbanization in Henan province as an example, a mathematical quantitative model was established to measure the subsystem order degrees and the composite system synergy degree from 2006 to 2015. The results were consistent with the actual situation and indicated that over time, sustainable urbanization in Henan developed towards a more harmonious and orderly state, though the overall synergy degree was not high. It was found that the model was a sound basis for scientific judgment and effective decision-making when seeking to coordinate sustainable urbanization.