Allow rainwater to seep away or use it after all?
Rainwater can not only bring blessings. Too much of it quickly becomes a problem and can cause considerable damage through flooding. Consequently, protection from water and its rapid removal used to be at the forefront of urban planning.
Sewer systems were built throughout the country to remove rainwater quickly and efficiently. However, heavier rainfall events and continuous densification in urban areas are increasing the pressure on these sewer systems. In combined systems, in which rainwater and wastewater are discharged together, the capacity bottleneck propagates to the sewage treatment plants. This is why decentralised rainwater management is becoming more and more important for planners all over the world.
The best way to do this is to use the valuable resource of rainwater directly on site.
There are several ways to relieve the sewer network of excessive rainwater inputs and to manage rainfall locally:
- Store and use: First and foremost, of course, is the use of this decentralised resource, which is available almost everywhere in the world. It is used to irrigate plants or sports facilities, in households or in businesses. Rainwater systems with filters and cisterns or rain barrels are used for this purpose.
- Retention: Short-term storage of water using retention cisterns to then slowly release it to the sewer system, reducing peak loads.
- Surface infiltration: Surface infiltration takes place via unsealed surfaces, ideally via the revitalised soil zone. Basically, green areas, gravel beds or paving stones with joint infiltration can be considered. The water seeps through all soil layers, is cleaned naturally and fed into the groundwater.
- Undergroundinfiltration: With the help of infiltration systems such as infiltration trenches, infiltration blocks or infiltration shafts, rainwater can be channelled directly underground and infiltrated there. The requirements for this vary from region to region and often require approval to protect the groundwater. In some cases, filters must be installed upstream to replace the natural purification via the living soil zone.