Look at how developed countries utilize rainwater resources

Let rainwater live with the city

In Sumida District, Tokyo, Japan, rain barrels named "Tensui-son" and "Roji-son" can be seen everywhere on the streets. Underground rainwater tanks. The rainwater from "Tian Shui Zun" is usually used for watering flowers and plants, washing cars, and cleaning windows. The water from "Lu Di Zun" can be pumped out using a water press or connected to other water conservancy facilities as part of the water cycle to reserve water sources. In addition to these facilities for each household, there are 185 large facilities that utilize rainwater in Sumida City, which is only 13.75 square kilometers. The capacity of the large water tank alone reached 12,527 cubic meters on April 1, 2008, which is equivalent to The water storage capacity of 45 25-meter swimming pools (approximately 275 cubic meters).

In the process of urbanization in Japan, most of the small rivers in urban space have been "encroached" by roads. However, after the 1990s, rivers were re-excavated in many places in Japan, and rainwater became gurgling streams again, instead of flowing across the roads like a vast ocean. The river is also connected to the "rojizun" of various streets in Japan. When there is too much rain in the rainy season, the overflowing rainwater from the storage tank can flow into the river like a waterfall; when there is little rain in the dry season, the water in the river can flow back to the rainwater. Storage tank. The gurgling water is always refreshing.

Next to the "Roadijon" is often a point for recycling renewable materials and fire-fighting water. This "ecological neighborhood" design continues the unique "wellside culture" in Japanese history and has become a solid foundation for A place where people connect with each other. Therefore, "Lu Di Zun" not only ensures the safety of drinking water during times of crisis, but also cultivates a spirit of cooperation among residents and consolidates the belief in joint efforts to respond to disasters. The naming of "Tianshuizun" is also very knowledgeable. In the words of the designer Deyong Changnan, "Tianshuizun" means respecting the rain from the sky. The reason why it is named like this is to hope that people will respect and protect nature.

Many single-family households in Germany generally collect roof rainwater through rain drain pipes, remove particulate matter in the runoff through dispersed or centralized filtration, and then introduce the water into the reservoir for storage, and then transport it through water pumps. To the water unit, it is used for laundry, flushing toilets or irrigating green areas.

A single-family home can build an independent rainwater collection tank, but how to collect rainwater in already built residential buildings? Some experts in Japan have started to make a fuss about the downpipes of residential buildings. Based on the principle that most rainwater flows along the inner wall of the downspout, they invented a ring with a certain width placed inside the downspout joint. When the rainwater on the inner wall is intercepted by the ring, it will flow into another pipe and rainwater storage tank leading to the residents on each floor. After the rainwater tanks of high-rise residents are filled, the rainwater will continue to flow downward along the downpipe, allowing users on all floors to All received rainwater.

Through these facilities and systems, more and more places in Japan, like Sumida Ward, bid farewell to the simple drainage of rainwater, and realize the integration of rainwater and cities through the collection, storage, infiltration and utilization of rainwater. ***born.

Public public facilities make clever use of rainwater

The Ryogoku Kokugikan in Sumida-ku, Tokyo is a pioneer in the country's use of rainwater in large public facilities. The roof of the Kokugikan can collect 1,000 cubic meters of rainwater, which can be used to flush toilets. It can also be used for air-conditioning equipment in summer. When it snows in winter, it can also spray water to melt the snow accumulated on the roof.

Similarly, Sumida Ward has also installed rainwater utilization facilities in the district government office building, formulated a system to provide subsidies for households and companies to use rainwater, and established a rainwater utilization information release center. In October 1995, Sumida City implemented a rainwater utilization promotion subsidy system. Rainwater tanks under one cubic meter can be subsidized for half of the cost, large-scale underground storage tanks can be subsidized up to 1 million yen, and medium-sized storage tanks can be subsidized for 300,000 yen. Yuan.

Led by Sumida Ward, more and more local governments in Japan have begun to provide subsidies for the construction of rainwater utilization facilities. Currently, 3,400 high-rise buildings across Japan have introduced rainwater utilization systems, including 1,000 high-rise buildings in Tokyo. Among them, dome stadiums across Japan are "big users" of rainwater.

The Osaka Dome Stadium has a water storage tank that can store up to 3,400 cubic meters of rainwater. The annual rainwater utilization reaches about 6,000 cubic meters, which is equivalent to about 35% of the sports center’s annual water use.

Coincidentally, in Germany, federal and state laws also stipulate that new areas must be equipped with rainwater utilization systems, otherwise they will face high rainwater discharge fees. To this end, developers mostly adopt the plan of laying vegetation on the roofs of buildings, which can not only delay rainwater runoff, but also increase rainwater evaporation and increase air humidity. Some roofs that are not suitable for planting vegetation follow the Japanese approach and build larger-capacity reservoirs, or introduce underground reservoirs through downspouts, and build water features such as fountains according to local conditions to integrate the use of rainwater with the surrounding environment.

At the Munich International Exhibition Center, designers collected rainwater from the roof of the exhibition hall into an underground reservoir with a total storage capacity of 2,500 cubic meters, and transported it through a pumping station to an artificial lake with a water surface of nearly 25,000 square meters. . There is a tall fountain in the lake, aquatic plants are planted around the lake, and water birds fly on the lake. They complement the tall exhibition halls and show the grandeur and splendor of the exhibition center.

Similarly, in the Netherlands, known as the "Low Country", about a quarter of the land is below sea level, including DD Rotterdam, one of the world's largest port cities. Being built on water has brought business opportunities to Rotterdam, but it has also exacerbated the threats of rising water levels and seawater intrusion. Rotterdam had to adopt a new strategy and constantly update its "arsenal" for water control.

The "Water Square" that attracted much attention at the 2010 World Expo is one of Rotterdam's secret weapons. The "Water Plaza" consists of several pools of different shapes, sizes and heights, connected by canals. Normally, this is a square for citizens to have fun and relax; once a heavy rain comes, the square becomes a flood prevention system, absorbing rainwater from all directions. Rainwater in the square can not only circulate in different pools, but can also be extracted and stored as fresh water resources. In the next few years, Rotterdam plans to build more than 25 "water squares". With enough "water squares", no matter how heavy rainstorms and floods are, they can be easily "tolerated" by the water squares.

The concept and technology of collecting and reusing rainwater resources is also one of the most beautiful scenes at the Shanghai World Expo. For example, in the "Zero Carbon Pavilion" in the London Case Pavilion, the north-facing roof of the entire building is covered with green landscape vegetation. When it rains, the rainwater collection system on the roof starts to work and automatically irrigates the roof vegetation. These plants are not only used as decoration. It also plays an indispensable role in neutralizing carbon emissions.

The vitality of rainwater utilization

Germany, Japan and the Netherlands are all countries with relatively abundant water resources. There is no obvious water shortage problem, but they are still able to promote rainwater utilization technology on a large scale. . The reasons are nothing more than the following aspects.

First, re-understand the value of rainwater. The annual rainfall in Tokyo, Japan, exceeds the water consumption of local tap water. If all the rainwater in Tokyo can be collected and utilized, Tokyo, Japan, will no longer have to rely on a reservoir 150 kilometers away, and it will no longer have to worry about groundwater pollution like other cities. The collection exceeded the standard and the ground subsided. Similarly, the urban floods that have occurred in places such as Fukuoka and Nagoya in recent years, as well as the water shortage dilemma faced by Osaka due to reduced rainfall and lower reservoir water levels, will be easily solved.

Second, through legislative and economic means, levy rainwater discharge fees to encourage people to choose rainwater utilization measures from an economic perspective. The German Water Resources Management Act, which was officially implemented in March 2010, stipulates that rainwater flowing from the roof into the sewer when it rains is considered sewage just like domestic water, so it must also pay sewage treatment fees. And this treatment fee rate is very high, usually 1.5 times the tap water rate. Once residents install rainwater utilization equipment, they can save this cost. The government encourages businesses, communities and private households to install rainwater utilization facilities.

The Tokyo Metropolitan Government formulated the "Tokyo Metropolitan Rainwater Infiltration Guidelines" in July 2001 to promote rainwater infiltration and avoid urban flooding while ensuring timely recharge of groundwater. Through facilities such as permeable pavements, side ditches, permeable pools, and surface green spaces, rainwater falling on roofs, courtyards, sports fields, and parking lots is collected and seeped into the ground.

At the same time, the government has also imposed strict regulations on construction methods and materials used, with the goal of allowing 80% of the annual precipitation to penetrate into the ground. In order to protect urban groundwater resources, a city on the Indonesian island of Java also made similar mandatory regulations on rainwater recharged land.

Third, promote the participation of social forces and enhance people’s awareness of rainwater resources. There are a large number of non-governmental organizations in Japan that vigorously promote rainwater utilization by popularizing rainwater utilization technology, holding seminars, and holding publicity activities. The citizens' organization "Usame Citizen's Association" located in Sumida Ward is a nationwide organization. There are many similar public welfare organizations and academic organizations distributed throughout Japan. Several universities are also studying rainwater utilization projects. These organizations not only promote rainwater utilization in Japan, but also promote rainwater utilization experience in other developing countries.

As the slogan engraved in the world's first rainwater museum located in Sumida-ku, Tokyo, Japan: "The problem lies in water, the solution lies in rainwater." When rainwater flows away, it becomes a flood, and when it remains, it becomes a resource. Utilizing rainwater will not only help alleviate the "water crisis" faced by urban development and solve the problem of urban flooding, but also help cultivate people's awareness of resources, create a water-friendly urban space, and make urban life better.