Use wechat to scan the QR code < / P > < p > to share with friends and circle of friends < / P > < p > Author: Wu Simin editor: Xu Huiyun < / P > < p > a rainstorm that is hard to encounter in a thousand years, Zhengzhou, which gives way to the junction of the middle and lower reaches of the Yellow River, has become the concern of the whole society, and also aroused people's attention to the construction of sponge city As a pilot city of "sponge city" in Henan Province, Zhengzhou has been built for nearly five years. In May this year, a report in Zhengzhou Daily said that since the implementation of the sponge city construction, a total of 125 waterlogging prone spots have been eliminated in Zhengzhou, with an elimination rate of 77%. So, why didn't Zhengzhou's sponge city construction prevent disasters < p > "this once-in-a-thousand-year rainfall has reduced 1 / 3 of last year's rainfall in one day. At this time, if we only talk about engineering methods and facilities construction standards, it is divorced from reality, time scale and risk probability, and the most important thing is disaster relief. For a once-in-a-thousand-year disaster, we are unlikely to resist it through daily prevention and try our best to do a good job in disaster prevention and reduction. " LV Hongliang, vice president of the ecological and Municipal Administration Institute of the China Academy of urban planning and design, said in an interview with China first finance and economics < p > he said that from the perspective of geography, Zhengzhou is in the waterlogging prone zone. In China, the subtropical high generally reaches near the Yellow River Basin. This year, the warm and humid air flow brought by the subtropical high is very strong, resulting in heavy rainfall. Zhengzhou is located in the transition zone from the middle and lower reaches of the Yellow River to the Huang Huai plain, and the terrain is relatively low. The Yellow River has become a suspended river in Zhengzhou, increasing the difficulty of drainage and resisting the risk of rain and flood < p > in his opinion, the view that "waterlogging in Zhengzhou is the failure of its sponge city design" is biased“ In fact, the return period of waterlogging prevention and control design in Zhengzhou city is matched with its urban scale. If it is designed according to this extreme situation, it will cause serious waste of resources. " < p > on July 20, vehicles waded along the streets of Zhengzhou. Xinhua News Agency Photo < p > according to the flood control standard (GB 50201-2014) issued by the Ministry of housing and urban rural development, in urban protection areas, areas with permanent resident population of 1.5 million or more and equivalent economic scale of 3 million or more belong to the first-class protection level, and the flood control standard (return period / year) is at least more than 200 years. According to the data of the seventh population census, Zhengzhou, with a permanent resident population of 12.601 million, ranks tenth in China's cities and first in Central China, which belongs to this kind of protection level < p > in 2016, Zhengzhou became one of the pilot cities of sponge city construction in Henan Province. In 2017, Zhengzhou sponge City special planning (2017-2030) was issued. In terms of water safety, the standard is: the return period of waterlogging prevention and control design in urban and aviation cities is once in 50 years, and that in other planning areas is once in 20 years. The flood control standard of the planning area is once every 200 years. The standard rate of drinking water quality is 100% < p > "Zhengzhou meteorology" official microblog news said that Zhengzhou Meteorological Bureau made a data analysis and statistics on the torrential rain: from 20:00 on the 17th to 20:00 on the 20th, the rainfall in these three days reached 617.1mm. Hourly precipitation and single day precipitation have broken through the historical records of 60 years since the establishment of Zhengzhou station in 1951. The average annual rainfall in Zhengzhou is 640.8mm, which is equivalent to the amount of the past year in these three days. From the perspective of climatology, the probability of hourly precipitation and daily precipitation, and the return period are all once in a thousand years < p > "but from the perspective of planning, there is still room for improvement." A professor from the school of civil engineering of Tongji University said in an interview with the reporter of first finance and economics that in urban planning, each city will define the precipitation construction scheme of its subway construction according to the precipitation in previous years. For Zhengzhou, where the population density increases rapidly and the engineering construction intensity is high, the surface water storage space of the city is not enough, and the expected precipitation standard of urban rail construction needs to be set higher and updated more timely < p > "but the change of the standard will affect the whole body. The cost of construction and transformation is high, and multi department coordination is needed. " The professor further said < p > the professor also said that in recent years, with the acceleration of urbanization, the degree of land development in various regions has increased significantly, followed by the decline of soil water capacity and the increase of land hardening rate. When rainstorm comes, the instantaneous surface runoff increases and the risk of waterlogging increases < p > LV Hongliang also believes that for the cities that have developed into super large and super large cities, due to the concentration of population and the strong ability of resource concentration, they have high exposure and great losses when encountering major disasters < p > "this means that the basic principles of such urban planning and construction should include maintaining the hydrological process as far as possible, reserving the space for rainwater storage and drainage, rather than digging lakes for landscaping, so that the original wetland ponds are squeezed and eroded by a large number, and there are few greenways left. In this case, the larger the scale of the city, the greater the loss." Lu Hongliang said < p > how to reduce the post disaster losses when the disaster is unpredictable < p > "appropriate redundancy of urban disaster prevention and mitigation capacity is particularly important, which is also the requirement of our resilient city construction." Specifically, we can reduce urban density and urban exposure by reserving pre control protection space, rain flood space and disaster reduction space, Lu Hongliang said; Through the construction of moderate redundant facilities, improve the level of defense; Through moderately improving the construction standards in the new town, including improving the urban elevation, expanding the reservation of drainage channels, improving the capacity of drainage network and promoting low impact development < p > "due to the proper planning, the new town and new area will be less affected when the disaster comes. For example, the Zhengdong New Area and the Sino Singapore eco city when Tianjin was hit by a typhoon on July 24, 2018. " He said < p > in addition to planning, prevention and control should be the first and disaster reduction should be the second, experts interviewed said that emergency response capacity and post disaster recovery capacity should also be improved. For example, by expanding the coverage of temporary meteorological reports, early warning and more relaxed and conservative plans should be made before possible major disasters come, such as temporary home office on the same day, stopping major public activities and meetings, doing a good job of forced drainage equipment and emergency rescue team arriving at the post ahead of time < p > "emergency management should also take into account a larger scope and focus on some aspects." Lu Hongliang explained that the rainfall center is not in the center of Zhengzhou, and the scattered small county towns may be ignored due to low density, but their facilities are relatively low and fragile, and their emergency response capacity is weak, which may also lead to relatively large losses; However, in the old city, the facilities are short, and the basic pipe network system and sponge transformation have not been fully implemented, which reduces the possibility of disaster reduction to a certain extent < p > < p > LV Hong ?
2023-03-22 10:04:38