Alma raingarden
Increased rainfall and urban development increase the risk of flooding in many areas. More rainwater and stormwater has to be handled locally. Authorities and developers are looking for solutions that use water and plants to add value to a development in additon to handle the water. Therefore, naturebased solutions are encouraged. At the same time, the construction industry is looking for solutions that have a predictable function, that are well documented and that are easy and quick to install.
Alma Raingarden is a pre-fabricated raingarden that can be used to handle runoff water from roofs and open spaces. It is a nature based solution that is flexible, that can be adapted to a local situation, that works during winter time and that can be built with a large detention capacity. In addition, it provides growth space for plants and it has internal storage capacity for water which is useful for the plants in dryer periods.
Technology demonstrated in relevant environment.
Representative model or prototype system, which is well beyond that of TRL 5, is tested in a relevant environment. Represents a major step up in a technology’s demonstrated readiness. Examples include testing a prototype in a high-fidelity laboratory environment or in a simulated operational environment.
Representative model or prototype system, which is well beyond that of TRL 5, is tested in a relevant environment. Represents a major step up in a technology’s demonstrated readiness. Examples include testing a prototype in a high-fidelity laboratory environment or in a simulated operational environment.
The function of the Alma raingarden has been validated in our own laboratory. Runoff from a particular rain event has been measured and a flow model has been constructed. Two pilot raingardens were installed in 2017 providing growth media for high growing plants. 10 pilot raingardens have been installed to receive runoff water from a roof, however, building activities have not been completed yet and reliable results have not yet been obtained.
How does it work?
Rainwater is guided to the Alma raingarden from roofs or from runoff from open spaces. The Alma raingarden works in three steps:
1. Small amounts of rain will accumulate on the surface of the Alma raingarden and from there infiltrate through the growth media.
2. For medium amounts of rain, water will run directly into the overflow pipe and into the detention chamber. The detention chamber is emptied by infiltration to the ground or through an orifice to the public drainage system. The detention volume can be be significantly increased if it is mounted in a crushed stone basin or another detention basin.
3. For large amounts of rain, water can run into a surrounding raingarden or detention space on the surface.
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