If there is no heavy rainfall upstream, freshwater supplies will be in danger Weather experts predict the west Pearl River Delta will be hit by more saline tides this year. Recent water flows and levels are below those of last year when the central government ordered the discharge of water from reservoirs in Guizhou and Guangxi to flush out saltwater tides. The salt tide occurs when sea water floods coastal areas because of serious drought. More than 1,000 experts had been monitoring water levels in rivers, lakes and reservoirs, and sounded the alarm over the National Day holidays, state media reports said. Zhongshan experienced its first saltwater tide this year on September 23, nine days earlier than last year, and experts fear that if there is no heavy rainfall upstream, the situation will be critical again in Zhongshan and Zhuhai this year. Conditions were so bad last year that residents of Zhongshan, Zhuhai and Macau had to put up with water cuts or salty water in their water supply, but the action by the central government gave them freshwater for 20 days during the Lunar New Year period until they were relieved by the rainy season. At Gaoyao , the water flow of the Xijiang, or West River, which supplies Zhongshan and Zhuhai, dropped below the critical 2,000 cubic metre per second level for pushing out saltwater tides for long periods last month. Although there was flooding earlier in the year and a cluster of typhoons have recently dropped more rain on Guangdong compared with last year, when the drought was severe, experts say the 14 million cubic metres of rainfall dropped over a wide area by Typhoon Damrey was not enough. With only about 10 days left of the rainy season, experts are concerned that the water levels and flow will be too weak to hold out the saltwater tides. Last month, the Xijiang's peak flow was 2,100 cubic metres per second lower than last year, while the average flow was down by 1,952 cubic metres per second. The water level fell so low in the Xijiang just before the National Day holidays that 500 vessels were grounded.