The opening of China’s first new river-to-sea canal since 1949 – which will boost trade links with Southeast Asia – could transform the economy of the country’s landlocked southwestern interior in ways comparable to the Yangtze’s role in Shanghai’s rise, according to its operator. The 134.2km (83.4 mile) Pinglu Canal, which opened on Wednesday, links a major tributary of the Pearl River in the southern Guangxi Zhuang autonomous region with the Gulf of Tonkin, known as the Beibu Gulf in China,...