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New drainage system aims to provide better growing conditions for city trees
As the city of Darmstadt announced, two tree trenches on Robert-Schneider-Straße on Wednesday (12th) . This is another project the city is implementing as part of its climate adaptation strategy.
Head of Civil Engineering Paul Georg Wandrey and Head of Green Spaces and Planning Michael Kolmer emphasize the importance of the project:
“Tree trenches offer urban trees better long-term growing conditions under changing climatic conditions and contribute to making urban drainage sustainable. With the tree trenches, the city of Darmstadt is testing a future-oriented drainage system that combines ecological and technical aspects.”
Selection of locations and functionality
The project began with an investigation of 36 suitable locations in the city center. Criteria included groundwater level, soil permeability, existing utility lines, available street space, and distances to buildings. The suitable sites are now located at house numbers 22 and 32 on Robert-Schneider-Straße. Five parking spaces will be lost as a result of the project.
The two tree trenches are constructed identically:
- Each trench comprises a bed of approximately six square meters , bordered by a raised kerbstone.
- The road surface will be designed so that rainwater flows into a newly created drain via a slight slope.
- In summer, a substrate filter cleans the water before it enters the trench and thus reaches the tree roots.
- In winter, the filter is closed due to possible de-icing salt contamination, so the water flows into the combined sewer via a conventional inlet.
Urban trees in a climate change
Wandrey and Kolmer point to the increasing strain caused by heat, drought, and low humidity. This results in visible damage to urban trees. At the same time, these trees are indispensable for the microclimate: they provide cooling, shade, CO₂ absorption, and improve the quality of life in densely built-up areas.
Federal funding and model character
The measure is supported by the federal program "Adapting Urban Spaces to Climate Change" with a 90 percent funding rate . It will be implemented based on the Stockholm model , which enables a particularly efficient supply of water and nutrients to urban trees.
The city of Darmstadt plans to apply the insights gained to other areas within the city.
(Darmstadt - Red/PSD/Stip)
