TAIPEI, TAIWAN – Discovery of a rare freshwater reserve under one of its land holdings in a widely disputed sea gives China a boost in occupying the islet and offers it a new defense for its sovereignty claims if they land in international court.

A freshwater lens is forming under Fiery Cross Reef in the Spratly archipelago of the South China Sea, Chinese researchers said in the peer-reviewed publication Hydrology Journal. The lens created by tidal activity will take 20 years to become “stable” at 15 meters thick, the South China Sea Institute of Oceanology researchers in Guangzhou said in the May 2020 study.

“Having this freshwater access evidently will change the quality of life and change their ability to station people on the artificial island,” said Yun Sun, East Asia Program senior associate at the Stimson Center research organization in Washington.

Most among the hundreds of islets in the 3.5 million-square-kilometer sea are semi-submerged or too small to support freshwater supplies. China used reclaimed land to build up Fiery Cross Reef to its current 274 hectares and now operates an airbase there with several hundred personnel.

The presence of water could mildly help China in any international court case to argue that Fiery Cross deserves a 370-kilometer-wide ocean exclusive economic zone, analysts say. Brunei, Malaysia, the Philippines, Taiwan and Vietnam contest all or parts of China’s claims to the sea. They prize the waterway for its fisheries plus undersea reserves of oil and gas.

The United Nations Convention on the Law of the Sea considers an islet’s ability to sustain life or economic activity when deciding whether a country can draw up an exclusive economic zone, but in 2016 the Permanent Court of Arbitration rejected that right for Taiping Island, a Taiwanese-controlled Spratly feature with its own water supply.

China leads the other claimants in firepower, technology and scientific research. It may have explored other South China Sea holdings for freshwater as well but found some only on Fiery Cross Reef, Sun said. Vietnam, Taiwan and the Philippines claim sovereignty over the same reef.

Finding water will at least boost Chinese morale, said Alexander Huang, strategic studies professor at Tamkang University in Taiwan.

“These are somewhat psychological building blocks,” Huang said. They imply, he said, that the Chinese “are making progress, they are moving on, but I don’t think in real terms they can actually use the limited freshwater to do anything so strategically.”

A local freshwater source will cut the costs of shipping water to Fiery Cross Reef or desalinating it, analysts note. That advantage would make it easier to station troops there. Woody Island, a Chinese-held South China Sea feature with about 1,000 long-term residents, collects rainwater and gets additional water shipped in.

But the freshwater lens won’t give China enough water to support a “sizable” fighting force on the ground, Huang said.

“It doesn’t change the balance of power in the region,” said Carl Thayer, Southeast Asia-specialized emeritus professor at the University of New South Wales in Australia. “It doesn’t give China a stronger leg up in any aspect. You could catch rainwater and store it and treat it and drink it, if you have the space.”