Why can't Zhengzhou, a "sponge city", cope with this rainstorm?

"Now a large part of the city is composed of hardened roads and high-rise buildings, and rainwater cannot penetrate. It is indeed necessary and significant to build a' sponge city', but it can't cope with this rainstorm. "

? "Sponge City" can only play a role in light rain? In recent years, the term "sponge city" has gradually attracted attention. 20 16 Zhengzhou was selected as the provincial pilot of "sponge city" construction in Henan province. At that time, the recurrence period of flood control design in Zhengzhou City was once every 50 years, while that in other planning areas was once every 20 years.

In view of why Henan failed to play the role of "sponge city" this time, "sponge city" can only play a role in moderate rain or light rain, and once it encounters a torrential rain, it cannot cope.

How much role can a "sponge city" play in the face of heavy rainfall? "Sponge City" can only allow normal rainwater to penetrate into the ground and eliminate ground water accumulation, thus promoting local infiltration of urban surface runoff and sustainable circulation of rainwater. In case of rainstorm, other measures should be taken, such as building deep underground tunnels, storing water in heavy rain and pumping water from rivers and lakes in sunny days.