Sponge city: Sustainable urban planning for the future
The ‘sponge city’ concept aims to collect and store rainwater where it falls instead of quickly draining it away via the sewer system. This is intended to prevent flooding during heavy rainfall events, improve the urban climate and promote the health of urban trees.
Cities are increasingly facing challenges: rising temperatures, increasing heavy rainfall events and a sealed infrastructure that can no longer absorb water naturally. The concept of the sponge city offers a solution for dealing with these challenges in a sustainable way. The facts and figures speak for the relevance of the sponge city: 30 percent more heavy rainfall events in the last 20 years, up to 5 degrees cooler temperatures thanks to green areas and a 50 percent reduction in the load on the sewage system thanks to decentralised infiltration speak for a sponge city concept.
Rapp AG is committed to the realisation of the sponge city and offers innovative solutions for sustainable planning and construction. These include water-sensitive urban development measures such as the planning of water-permeable surfaces, green infrastructure or rainwater management, all of which contribute to the climate resilience of cities. With well thought-out concepts, Rapp AG combines ecological responsibility with innovative urban development - for a sustainable, liveable future.
Questions and answers about sponge city
What is a sponge city and how does it work?
A sponge city is a concept that allows a city's structures to absorb as much water as possible. This means that it is not discharged into the sewage system, as is common practice in many cities today. Instead, the water is stored and released slowly. This happens when it seeps away or evaporates.
The sponge city helps to prevent flooding during heavy rainfall. The concept also improves the urban climate, promotes the formation of new groundwater and increases biodiversity. Because of these positive effects, Rapp actively supports the implementation of the sponge city principles.
The concept is realised technically and conceptually as follows:
Areas are unsealed.
- Permeable coverings such as lawn joint paving stones are used.
- Green spaces, parks, wetlands, hollows, ditches and retention basins are created as water reservoirs.
- Roofs and façades are planted with vegetation, which serves not only to store water, but also to cool the buildings.
- Trees that store water and provide evaporative cooling are planted in locations with sufficient root space.
What advantages does the sponge city principle offer for urban areas?
An important advantage of the sponge city is that it reduces the risk of flooding during heavy rainfall. In addition, the concept relieves the burden on the sewage system because rainwater is not discharged into it.
The sponge city also improves the city's microclimate. This is achieved by evaporative cooling, among other things. As the stored water evaporates, it lowers the ambient temperature. In addition, trees and other plants are effectively supplied with moisture. This is particularly important during dry periods. In addition, the seeping away of the stored water promotes the formation of groundwater.
And last but not least, the quality of life and biodiversity are higher thanks to the sponge city. The air quality improves and there are numerous green spaces for exercise and recreation.
How does Rapp put the sponge city principle into practice?
Rapp is involved in the realisation of the sponge city with various measures. We take this principle into account in urban development and site planning from the outset. As general planners, we are responsible for the corresponding design of traffic, access and open spaces. We also plan the infrastructure for supply and disposal.
In the case of existing structures, we advise on the adaptation of the drainage system. We support our clients in the step-by-step transformation.
If former industrial buildings are to be converted, we design the entire process. This begins with the opening of the site and continues through dismantling to the adaptation of the infrastructure. Structures are created for living, working and socialising – all with the principles of the sponge city in mind.
Among other things, we plan open spaces in which rainwater can seep away and evaporate. We are also responsible for designing retention areas to protect against flooding. In addition, we can adapt existing drainage systems on request.
What innovative technologies does Rapp use for sponge city projects?
To transform cities into sponge cities, Rapp provides consultation on the creation of permeable surfaces and pavements. Permeable paving stones and permeable road surfaces are possible options. Areas are also unsealed so that rainwater can seep away. We are also designing a blue-green infrastructure that favours green spaces and water areas.
At a technical level, for example, we implement smart rainwater management. We use sensors to determine values such as soil moisture, water level and temperature, and couple them with automated irrigation systems.
Artificial intelligence can also be used to analyse weather data and detect heavy rainfall events at an early stage. AI can also control systems that drain or store large quantities of rain. Among other things, water sluices, canals and retention basins are used.
Modular storage systems can also be used for the general storage of rainwater. Underground block storage tanks and infiltration trenches, which release excess water into the groundwater in a controlled manner, are particularly suitable.
Rapp takes an interdisciplinary approach to sponge city planning. We work with teams whose members come from different disciplines. This ensures that our solutions and strategies are as innovative as possible.