Saving cities from rains

Chinese cities should have a good sewerage system to deal with heavy rains, says an article in Beijing News. The following is an excerpt:

In recent days, several southern provinces have suffered heavy rainstorms. Shenzhen authorities said the rainstorm that hit this city's Baoan district was the worst in half a century and the drainage system could not dispose of the large rainfall quickly so that many roads, residences and factory plants were flooded by the rain, leaving six dead, one missing and great economic losses. From this case, we can see the standards of urban drainage system need to be improved.

In July 2004, Beijing was also hit by heavy rains, which flooded more than 70 streets and 4,698 rooms. As the Beijing authorities said, the heavy rainfall exceeded the capacity of the urban drainage system. Beijing has designed an urban drainage system to deal with the rainfall that takes place once in five years, but the advanced countries have designed it for the rainfall that happens once in a century or once in 300 years, said the authorities.