Shanghai plans to build two reservoirs to store rainwater under the 2010 World Expo site, a water authority official said yesterday.

To be built under the central part of the venue, the reservoirs can hold more than 100,000 cubic meters of water, said Chen Qingjiang, director of the planning department, under Shanghai Water Affair Bureau.

Pipes leading from expo's permanent buildings, including the Theme Pavilion, China Pavilion, Public Convention Center and Recreational Center will be connected to the reservoirs.

Channels along the roofs of the buildings will carry rainwater to the pipes, Chen said. A plant will separate the dust and other particles from the water that can then be used to clean roads and water plants.

Shanghai will get a lot of rain during the expo because it'll be held from May to October. The rainwater reservoirs will thus not only prevent waterlogging in and around the venue, but will also supply 109,700 cubic meters of water for irrigation even after the expo.

Expo organizers said they were still working on a detailed plan on how to collect and use the rainwater.

The Huangpu River will, however, be the main source of water for the expo site. "Most facilities will be near the Huangpu that can supply enough water for cleaning. What's more, the river is cleaner now," he said.

The Huangpu will help save at least 1 million cubic meters of tap water needed to clean the roads and maintain a green cover in and around the 5.28 square-kilometre venue.

Shanghai is one of the few cities in China that uses rain and river water for irrigation. Some farms in the Sunqiao area on the outskirts of the city use big canopy roofs to collect rainwater.

Also, the water bureau has begun using water from the Suzhou Creek to keep the areas along the river green.

In the Pudong area, water is pumped from nearby rivers to clean the city's outer ring roads, a move that can save precious tap water and up to 4 million yuan a year.

Chen said the water bureau planned to introduce more diversified rainwater collection facilities in the city to recycle rainwater. For example, it's now considering building underground reservoirs near elevated roads to collect rainwater that can be used for watering plants along the road.

source: China Daily