China is exploring the idea of building "sponge cities" to solve the problem of urban flooding. Hong Kong has used the concept in a decade of infrastructure upgrades.
Water-logging has plagued many cities in South China following this year's frequent heavy rainstorms but not Hong Kong, where some of the excessive rainwater is absorbed by large underground storage tanks.
"The operation mechanism is based on real time water level form four sensors. Any rainfall that excess the handling capacity of the downstream drainage network will be temporarily stored in this water tank. To altogether its capacity is 60,000 cubic meters of water, that's equivalent to 24 the water in 24 standard size swimming pools,"
Other water is intercepted and diverted into the sea through massive drainage tunnels.