Ten years ago, it would not have been unusual to find streets in Mong Kok flooded after heavy rain. But these days, even after severe tropical storms drench the city, the huge flows usually drain away swiftly. That change can be credited in large part to the efforts of the city's hydraulic engineers over recent years to harness unruly waters and prevent loss of life or damage to the city's infrastructure. Professor Joseph Lee Hun-wei is one of those who has dedicated his working life to this subject. The pro-vice-chancellor and Redmond Chair of Civil Engineering at the University of Hong Kong is the first Asian to be awarded the Hunter Rouse Hydraulic Engineering Award by the American Society of Civil Engineers. Presented on August 14, the award honours engineers and firms throughout the world for achievements in the civil engineering sub-discipline. Lee joined the University of Hong Kong in 1980 after obtaining his PhD from the Massachusetts Institute of Technology. He quickly learned that Hong Kong posed some unique challenges for a hydraulic engineer. 'First, Hong Kong has limited space, so water engineering projects must be compact. Second, water runs down our steep hills so quickly - as fast as 10 metres per second. Then we have many valuable buildings. It's very important that the buildings are not destroyed by the forces of water.' Lee and his team adapted a drain design, called the vortex intake, to suit Hong Kong's needs for rapid drainage. Seventeen of the drains are being installed in congested parts of Hong Kong Island, where the need to collect huge volumes of high-speed run-off is the most critical. Incorporated in the Hong Kong West Drainage Tunnel, the drains will solve the problem of flooding that still occasionally afflicts western parts of Hong Kong Island. Lee, who has served as an expert adviser to the Hong Kong government and as an international consultant, has a passion for his work. 'You never know when a problem will call on all your experience and experiments you have conducted,' he said.