With the progress of globalization and information and transportation technology, global urbanization has been rapidly growing to promote the emergence of the flow of people, logistics, capital, and innovation, which gradually evolves the location space into flow space, increasingly strengthening the connection network between cities, the complexity of the network structure in the flow space era as well as the intensity of the interaction between humans and nature. The spatial organization of all kinds of interacting factors also reflects the characteristics of multi-regional and multi-scale networks in terms of its form.

The spatial structure network is complicated in all aspects of human society, including urban networks, trade networks, social networks, innovation networks, human-land interaction networks, and the flow characteristics of various elements in the network. Thus, it is urgent to analyze the structural characteristics and evolutionary law of complex spatial structure networks under the background of rapid urbanization and flow space.

Regarding the complexity of this system network and the recently-formed and rapidly-developed uncertainty quantification, this Special Issue will focus on the new trends and characteristics of complex system networks such as urbanization, urban and social-economic spatial organization, etc., with expectations to promote the interdisciplinary integration of geography, urban science, complex systematic science, big data and information science, social economics, and other disciplines. The aim is to promote the theoretical methods and empirical research on the complexity of spatial networks. Original research and review articles are welcome.

Potential topics include but are not limited to the following:

• Flow space and spatial structure change
• Rapid urbanization, urban mobility, and urban networks
• Global cities and urban trade networks
• Global cities and urban innovative networks
• Embodied carbon emission flow networks
• Machine learning, artificial intelligence, and complex network analysis