A MASSIVE 300 per cent increase in cargo throughput predicted by 2011 underlines Hong Kong's urgent need for a new port. This was the conclusion of the Port Development Board (PDB) after it accepted port cargo forecasts presented to a full board meeting yesterday. numbs, container throughput can be expected to increase from nine million TEUs (20-foot equivalent units) lastyear to nearly 32 million by 2011. Overall cargo handled by the port will increase from 116 million tonnes last year to nearly 350 million tonnes by 2011. To cope with the increase, up to 25 new container berths will need to be built at a new Lantau Port. They will be sited at a new port extending south from Penny's Bay on Lantau Island. According to PDB calculations, the first berth of Lantau Port should begin operations in mid-1997 when the Tsing Ma Bridge is scheduled to open. The bridge will provide road access to the new port and Chek Lap Kok airport. The port cargo forecasts are prepared biannually by the PDB secretariat with the help of consultants. The forecasts show the effect that the tremendous growth in southern China's economy has had on Hong Kong's port, helping the territory retain the title of world's busiest container port. ''With Hong Kong's economy switching from manufacturing to service industries, the port is playing an increasing role in Hong Kong's economic development,'' said PDB secretary Tony Clark. ''Each container handled adds significant value to the local economy,'' he said. Between 1983 and 1992, port traffic grew by 11.9 per cent a year. The forecasts predict a 6.7 per cent annual growth between 1992 and 2011. An increased trend towards using containers will see container throughput grow by 7.6 per cent in the same period. The study found that the relocation of Hong Kong industry to southern China had created new cargo movement patterns. Hong Kong imported goods and re-exported them to southern China for processing or consumption. Manufactured goods from Guangdong were exported through Hong Kong, mainly to North American and European markets. The study found that most outward containerised cargo going through Hong Kong originated in Guangdong. The review concluded that Hong Kong would maintain its position as the premier hub port in southern China in the short to medium term. A survey of shipping lines showed that none was planning a major shift of services away from Hong Kong. The forecasts said that over the next five to 10 years port developments in southern China would be complementary to Hong Kong. ''They are unlikely to have adequate maritime support services, nor other ancillary services that are available in Hong Kong,'' the report said. It said additional shipping in the area generated by southern China port developments would help the growth of feeder services to and from Hong Kong. As Chinese ports increase, improve and expand, more international shipping lines would use them. But rather than losing trade to China, Hong Kong would handle the overspill as China's trade increases massively. Hong Kong's port cargo throughput would continue to grow, but at a decreasing rate, the report said. In preparing the forecasts, the PDB team took note of political and economic development in China and Hong Kong, regional economic development trends, Hong Kong's future role as an entrepot and transshipment hub, and potential competition from port facilities in the region, especially in the southern China hinterland.