For more on the construction of "sponge cities", we are joined in the studio by CCTV's Jin Yingqiao.

Q1. Tell us more features that a "sponge city" must have?

A1. It deals with multiple respects. The State Council has ordered that 20 percent of China's cities must become "sponge cities" by 2020, and right now 30 of them are running pilot programs.

But what is a "sponge city"?  As its name suggests, it's like a sponge that can absorb and release water, to prevent flooding and improve the city's ecological system. It's different from the traditional idea that all you want is to drain the water away.

The guideline says that 70 percent of rainfall should be absorbed and utilized locally. For a "sponge city" you need to build "green roofs", roofs that are covered by plants that can absorb and purify water for reuse.

You also need to build pavements that are penetrable by water, so it doesn't lodge on the ground, construct pumping stations to drain the water away, and underground pipelines and spaces are needed to hold the water.

One key area are wetlands, the country's natural water systems have been corrupted by human activities, and that needs to be changed. The State Flood Control and Drought Relief Headquarters said 180 cities experienced urban flooding from 2013 to 2015. So "sponge cities" are very important.

Q2. Are sponge cities difficult to construct and implement?

A2. Well, there's a lot of obstacles actually. First, funding. The central government allocates funding of 400 million to 600 million yuan to pilot cities. But that's not enough, so Premier Li Keqiang has given instructions to create innovative business models to attract private capital models like Public Private Partnership, or PPP, are encouraged.

For those that are using PPP and attract a certain level of capital, the central government will provide an additional 10 percent bonus. It is indeed a challenge, as one expert pointed out that in some other countries, building a sponge city takes up 20 percent of the funds for city construction and can total trillions of yuan.

The challenge of involving private money is that it's hard to find a model to bring them profit, because essentially you are spending huge sums of money for something that rarely occurs. So it really takes good planning. But of course, the benefits far exceed just preventing flooding, it makes the city a more habitable place.