Spatio-temporal evolution and influencing factors of land-sea coordination in China’s coastal areas

The ocean and the land have always been neighbors, but for much of human history, they have been managed as if they were strangers living in separate houses. Governments often draw a hard line at the shoreline, planning cities and farms on one side while regulating ports and fisheries on the other, rarely asking how the two sides affect each other. This separation creates a problem: what happens on the land, from the factories that pump waste into rivers to the roads that lead to the coast, inevitably changes the sea. Conversely, the health of the ocean dictates the prosperity of coastal towns. In recent decades, scientists and policymakers have begun to realize that treating these two systems as a single, connected unit is essential for survival and growth. This concept, known as land-sea coordination, asks a simple but difficult question: how well are a region's land-based economy and its marine economy working together, and what forces are helping or hindering that partnership?

A team of researchers set out to answer this question for China's eleven coastal provinces, tracking the relationship between land and sea over a seventeen-year period from 2008 to 2024. They treated the land and the sea as two distinct but interacting systems, each with its own health score based on factors like economic output, how well resources are used, technological progress, and environmental protection. By measuring these scores year by year, they could calculate a single number representing how well the two systems were synchronized. If the land was booming while the sea was struggling, or if they were both growing but in ways that hurt each other, the score would be low. If they were growing together in a balanced way, the score would be high. The researchers then looked for the specific drivers behind these scores, testing whether government funding, openness to international trade, the concentration of skilled workers, or the clustering of marine industries made a difference.

The results revealed a story of slow but uneven progress. Over the study period, the overall relationship between land and sea in China improved, moving away from a state of disorder toward a state of coordination. However, this improvement was far from uniform. The southern provinces, particularly Guangdong, pulled ahead significantly, reaching a level of coordination that the northern provinces had not yet achieved. While the land systems in most provinces grew steadily and quickly, the sea systems were more erratic, showing periods of rapid growth followed by sharp declines, such as a noticeable dip in 2020 before a rebound. The gap between the north and the south is stark; the southern regions are currently outpacing the north in how well they are integrating their coastal and inland economies.

Perhaps the most surprising finding concerns the role of industry. It is often assumed that bringing marine industries together in large clusters would help the economy and improve coordination. The data, however, told a different story. In the eastern coastal regions, where marine industries are most densely packed, this clustering actually worked against the goal of coordination. The researchers found that when marine industries become too concentrated in one area, they can create a bottleneck, competing fiercely with land-based industries for resources like water, energy, and space. Instead of working together, the two sides end up fighting for the same pie, which weakens the overall partnership. This suggests that simply building more ports or marine parks is not enough; without careful planning to link these industries with the inland economy, they can become isolated enclaves that hinder rather than help.

On the other hand, two factors stood out as clear helpers for land-sea coordination. Government support was the most powerful driver; when local governments provided funding and policy backing, the relationship between land and sea improved significantly. Similarly, opening up to the outside world through international trade and investment helped both sides grow together. The study also found that the impact of other factors, such as the presence of skilled workers or the standard of living, depended heavily on where you looked. In the north, having more researchers and engineers helped bridge the gap between land and sea, while in the south, higher living standards sometimes created pressure on the coastal environment that offset economic gains.

The researchers conclude that while China has made strides in connecting its land and sea, there is still a long way to go. The current state is often one of "barely coordinated" or "primary coordination," meaning the two systems are just starting to work together but are far from a seamless partnership. To move forward, the study suggests that governments need to be more strategic, especially in the north where progress has been slower. They recommend avoiding the trap of letting marine industries grow too large in one spot without connecting them to the hinterland. Instead, policies should focus on strengthening the links between the two, ensuring that the growth of the ocean economy lifts the land economy with it, and vice versa. The path to a truly coordinated future lies not in treating the coast as a boundary, but in recognizing it as a bridge where the land and the sea must rise together.