Researchers from Hong Kong and the mainland have developed a system that improves flood forecasts by 10 to 20 per cent compared with earlier methods based on individual experience. Dr Chau Kwok-wing, an associate professor from the department of civil and structural engineering at Polytechnic University, Professor Cheng Chuntian of Dalian University of Technology and Professor Li Dengfeng of Dalian Naval Academy received a second-class State Science and Technology Award for the joint project. Chau and his team analysed information on rainfall, floodwater levels and historical experiences of floods from mainland reservoirs over the past 50 years. Using the data and scientific principles such as pattern recognition theory, they developed a sophisticated theory that allowed for more accurate prediction of rainfall runoff. In the past, forecasts were made relying more on the experience of operators who open and close floodgates, Chau said. This led to accurate water-level forecasts for only 70 to 80 per cent of the time. 'Floods cannot be avoided entirely, but it's a matter of predicting when it will happen and the severity of it so that the extent of damage can be reduced,' he said. Based on the theory, the team developed a computer program to calculate and predict floods which has been installed at 100 medium-sized and large reservoirs on the mainland over the past two years, including the Three Gorges reservoir. The system was first installed at the Shuangpai reservoir in Hunan six years ago and made accurate forecasts for more than 90 per cent of the time, Chau said. Using predictions generated by the system, operators at reservoirs can control floodwater levels to within 1cm to 2cm. The system considers many factors, including irrigation and power generation, that are given different weightings in the calculations. The prevention of floods was given the most weight, Chau said. 'It takes time to improve accuracy,' he said, with the degree of improvement getting smaller as accuracy gets closer to 100 per cent. Data from each of the 100 reservoirs is shared in a network via satellite so that operators can better monitor distribution of water resources. Liaoning province nominated the project in the competition for the national honour.