He told the reporter that from a technical point of view, the annual rainfall in Jiangsu is about 1 100 mm, of which 70%-85% require stagnant flow and cannot be discharged. This will be controlled in the future planning. Runoff and permeable pavement will be written as important elements when land is transferred, and the displacement of land before and after development must be flat. This will not increase the pressure of municipal pipelines, but also achieve the effect of retaining flood peaks, and also avoid the "opening the belly" of roads.
He said that building a sponge city will bring shocks and challenges to traditional concepts. In the past, urban drainage relied on pipelines, canals, pumping stations and other facilities, and pursued "rapid drainage" and "terminal concentration" control; The main planning and design concept of sponge city is to control "slow discharge and slow release" and "scattered source". The reporter learned that many cities across the country are eager to try and are actively exploring the construction of sponge cities. But it is not easy to really build a sponge city.
Where did all the rain go? Unveiling the Mystery of "Urban Sample"
How to build a "sponge city" Zhenjiang has carried out a pilot test. On the 5th, the reporter followed the expert group to Jinshanhu Road in Zhenjiang City. On both sides of the road, there are no traditional rainwater pipes and green belts. Instead, it is a natural drainage system composed of grass ditches and vegetation with a width of 3.5 meters and a depth of 0.2-0.3 meters.
Hu Jian, director of Zhenjiang Drainage Management Office, told reporters that it seems normal, but there is a mystery hidden under the grass ditch. Under the pavement, low-impact development measures such as permeable pavement, concave green space, rainwater garden and rainwater trough are adopted. Hu Jian said that rainwater will enter the grass planting ditch through the opening of the road teeth, penetrate into the permeable blind pipe, and then be discharged into the water system through the rainwater crossing pipe. The super-infiltrated rainwater will enter the rainwater pipeline through the overflow well of the rainwater garden and then be discharged into the water system. Drainage, water storage and purification are not only drainage, but also sewage discharge, which has many uses.
The picture shows Zhenjiang sunken landscape park.
Zhenjiang has many such "coup". Zhouwan Road sidewalk and Jianger Residential Area are both under renovation. On Kwun Tong Road, the reporter saw that the landscape park here is a "collapsed" concave type, unlike ordinary parks that are parallel to the road or above the ground. "It is not only a park, but also a storage facility for flood control and excessive rainstorm, with a storage capacity of 600,000 cubic meters." .
Zhao Jiang, dean of the Urban Branch of Zhenjiang Planning and Design Institute, told the reporter, "They should not be underestimated. Permeable materials, holes and sunken "rain garden" can collect and purify rainwater. It rained heavily several times last year. We made a field trip and found no accumulation. " Where did the rain finally go? Zhao Jiang said that part of the groundwater was infiltrated, replenished and conserved, and part of it was still discharged into the water body after the "sponge" was saturated. However, after layers of infiltration, the water volume decreased and the water quality was purified. Lei Zhiqiang, deputy mayor of Zhenjiang, said that at present, Zhenjiang has built more than ten kilometers of ecological roads according to local conditions. New roads are built according to the above standards, and old roads are reconstructed. Compared with the original expansion pipe gallery, the construction of ecological road saves investment by 30%-60%. By the end of 20 17, the sponge city construction project has been fully completed in the 22-square-kilometer pilot area of Zhenjiang, with the total annual runoff control rate reaching over 75%, the drainage and waterlogging prevention standard reaching to effectively cope with the rainfall once every 30 years, and the non-point source pollution reduction rate reaching 60%.
Sean, executive director of the American Association of Landscape Architects? O 'Malley told reporters another vivid case. In 2009, he presided over the renovation project of Shunde water town in China. He believes that the main reason why the company won the bid is to "respect the status quo and tap the local characteristic culture". Shunde is a famous water town in Lingnan, with a dense water network. Sean's plan is to restore the original river water network in Shunde and restore its original vitality. After the water network is opened, it can not only store water for flood control, but also connect the water network to restore the past ecology and the characteristics of Lingnan water town. After the project was completed, the citizens said happily, "Lingnan culture is back!" Beware of "simplification" and prevent "arrival" and "sponge city" from happening overnight. Zhang Zhiwei, a registered landscape architect in California and a professor at San Francisco Academy of Fine Arts, told reporters that the United States has spent nearly 25 years and invested 2 billion dollars to gradually promote the construction of sponge cities. The construction of sponge city is a systematic project, rather than simply digging several ditches and building several landscapes. She Nian worried that many cities in China would become "sponge cities" and fell into a misunderstanding.
Zheng Xiao, an American registered landscape architect, has done many projects in Ningbo and Shunde, China. She told reporters, "In fact, the construction of a sponge city has infiltrated many details, and it is necessary to prevent it from being too simplistic and out of reach."
Zhao Jiang, president of Zhenjiang Planning and Design Institute, feels the same way. He said at the forum that Zhenjiang, as a sponge city, has almost no large-scale projects, and some have subtle changes. "Building a sponge city is not to overthrow everything, but to re-adjust existing resources in combination with tradition."
Zheng Xiao said with emotion, "China's cities are developing too fast, and some places have lost many of their original cultural features. What a pity! In the process of building a sponge city, we should try to preserve the' soul' of a place. "
Let the blueprint become a real beauty, but also rely on implementation. Zheng Xiao has handled many China projects, and the biggest regret is that "the preliminary planning and design were very good, but the construction process was halved because of the cost and the construction unit". In her view, if you want to build a perfect sponge city, you still need strict supervision and no regrets. Sean. O 'Malley said that the starting point of sponge city construction is not only flood control and drainage projects, but also to increase the interest of the city, let citizens participate and provide new leisure places.
In the 1990s, Sean hosted the "Sponge City" project in Houston, USA. He took out his mobile phone and showed the reporter the reconstructed river: there are trees on both sides of the river, houses everywhere, blond girls running, children playing, and green flowers and plants growing on the river bank. Who would have thought that before the project transformation, "no one came here at all, except sewage, which was basically abandoned."
The project is located in the Houston Delta, which suffers from floods every year. The initial idea of the Houston government was also "simple": nearly 500 kilometers of rivers were widened twice. But Shawn's SWA designer said, "Don't broaden it, respect it as it is."
"The transformation began in the 1990s, from the city center to the suburbs. Nearly 500 kilometers of rivers turn waste into treasure. The ditch turns straight, reducing the pressure on the river, and the two sides of the river have become four seasons scenic lines. Planting purified plants at the bottom of the river softens the river bed, which not only absorbs water but also is beautiful and reduces the pollution problem.
"If we only do it from the technical level, we can certainly realize the functions of flood control and rainwater collection, but its ecological value, economic value and social value are difficult to develop. This should be a comprehensive system, not just a project. " She Nian told reporters that building a sponge city actually requires a "Chinese medicine method", which requires multi-sectoral coordination and comprehensive consideration of ecological, social, cultural and economic values, rather than "treating the headache and treating the foot."
Before the press release, it was learned that more than 500 experts from China, the United States, Britain, Germany and other countries attended the meeting adopted the Zhenjiang Declaration on Engineering Technology Practice of Sponge City, and reached six understandings on accelerating the transformation of urban drainage system from gray scheme to green scheme and speeding up the implementation of urban and rural ecological restoration. The reporter believes that under the strong impetus, the future city will "breathe" like a sponge and truly build an ecological park where people blend with mountains, water, lakes and forests.