China has completed a high-resolution mapping of the seabed in its claimed waters, including the South China Sea, after more than two decades of work, according to scientists involved in the project.
The researchers say their methods have achieved twice the resolution and between two and five times the accuracy of the best global models. The effort has produced China’s first systematic seabed atlas, identifying and naming 769 underwater features in surrounding waters.
The strategic importance of detailed seabed information was highlighted in October 2021, when the US Navy’s Seawolf-class nuclear submarine USS Connecticut struck an uncharted seamount while submerged in the South China Sea. The collision grounded the vessel and injured 11 crew members. A subsequent investigation blamed poor voyage planning by officers on watch, who failed to heed sonar warnings that did not match their charts.
Had detailed topographic data for the area been available, the billion-dollar advanced submarine might well have avoided the accident.
Beneath the ocean surface lies terrain as rugged and varied as mountain ranges on land. Detailed knowledge of that terrain is important for covert military operations, seabed mineral development, research into ocean currents and the study of earthquakes. Yet only 28.7 per cent of the world’s oceans have been surveyed in detail, leaving 71 per cent largely unmapped.
In July, a team led by Professor Wu Ziyin of the Second Institute of Oceanography, under the Ministry of Natural Resources, received a second-class National Science and Technology Progress Award for its work.
The project began from what the ministry-backed China Natural Resources News described as weak theory, missing methods and outdated technology. Over the following decades, the researchers assembled marine survey data collected across different periods, projects, instruments and reference systems. The data came in different formats and effectively spoke different “dialects”.
Wu’s team developed techniques to combine and model these datasets, allowing them to produce a high-resolution and highly accurate digital map of China’s surrounding seas. The work represents a significant advance in the country’s ability to process and use large quantities of marine survey information.
The researchers also developed new equipment for seabed surveys. Their 6,000-metre-class (19,685 feet) autonomous underwater vehicles, including the Qianlong-4 and Orange Shark III, use low-noise, low-power propulsion and high-precision navigation and have entered routine operation.
For precise depth measurements, the team developed a domestically produced multi-beam echo sounder that, according to Wu, matches world-class performance. “Our equipment breaks the monopoly of Western countries, with leading performance,” Wu said in the news report. He added that imported multi-beam systems previously cost millions of yuan, while the domestic product costs only a few hundred thousand.
The project has also given China a stronger role in determining how underwater features are identified and named. Researchers followed standard naming rules while drawing on Chinese mythology, historical figures and classical poetry. A dictionary containing 769 names for features in China’s surrounding seas was compiled in 2021, while an English edition of the atlas is planned for international release this year.
The survey data and equipment have already been applied across domestic sectors including water conservancy, navigation channels, marine surveying and offshore wind power. The technologies have also supported shallow-water mapping, complex island-reef surveys, marine ranching and automated measurements in extreme areas.
China has also begun exporting the technologies to Russia, Japan and Singapore. “Now we have not only replaced those imports but are also exporting our own. That is a true qualitative leap,” Wu said.
Beyond technology, Wu has trained 45 graduate students, most of whom have become core personnel in marine science. “At the start, we could only envy the advanced equipment of others,” he recalled in an interview with Science and Technology Daily. “Now some of our technologies are leading globally – this is the result of generations of effort.”
