Go with the Flow
How cities around the world master water management.
Whether you live in the Netherlands or California: water is a double whammy for many cities around the world. Sometimes it is an increasingly scarce resource; sometimes it comes in abundance with heavy rains, storms or floods. Some cities even face both of these problems. To combat flooding, there is now a strong trend to go with the flow. Instead of fighting nature by fencing water out, they take water in.
Soaking the Water Up
Killing two birds with one stone: with Happy Valley, Hong Kong created a recreational area above a gigantic water tank.
Hong Kong's solution was to create the Happy Valley Recreation Ground: a free park with 11 playing fields, a jogging track, a horse racing course - with a massive underground storage tank beneath. During heavy rains, the tank fills with runoff, which is temporarily retained to protect the city against flooding. The tank can hold 60,000 cubic meters of water, or roughly the equivalent of 24 Olympic-sized swimming pools. The European record is held by the German city of Munich with 14 underground storage tanks that provide a total capacity of 700,000 cubic meters. Both cities are “sponge cities” – a term coined in China for cities with water retention capacities.
Bringing Ideas to Life
This is just one vision developed by cities for water management. Bringing these visions to life is a challenge to politicians, architects and engineers. Also, the right materials must be available. The water tanks for example are usually built with concrete or brickwork – materials which are easily damaged by water. This is where the chemical industry has come up with solutions to contribute to the future of our cities.
Waterproofing Construction Materials
There are different ways to protect mineral surfaces against water. Silicone- and silane-based impregnation agents are one option. Mineral waterproofing membranes are another. WACKER is an expert in both chemistries, offering sophisticated product solutions that have been refined and continuously developed to meet specific requirements in different regions around the globe.
With 1,000 mm average annual precipitation, Munich is one of Germanys most rain-laden cities. To cope, the city built 14 reservoirs with a total volume of 700,000 m3. The biggest is placed under the popular “Hirschgarten”: a park with a famous beer garden. Buried 16 m below the surface, the reservoir measures 210 by 37 meters. It consists of four smaller resevoirs. Reservoirs 3 and 4 are located beneath reservoirs 1 and 2. When the sewage drains overflow, they spill over into the reservoirs. After the rain, the water is pumped back into the sewer system.