“Only forty centimeters deep, the clear water of the Sihl rushes northwards over a rocky river bed. Dog walkers and cyclists drift past the reeds, alders and beeches that line the lush banks of this natural idyll in the centre of the Zurich. Yet despite appearances, it is the Sihl, more than the Limmat that is the product of human design and construction. The path of the Sihl through the city has been made and remade many times over the centuries to suit differing human requirements and, perhaps most importantly, as a means of controlling the natural flooding caused by overflows of the river delta.”
Since a weir has been build at the upstream Sihl lake, the water depth in the urban Sihl delta can be controlled much better. A hydrological analysis of this part of the river Sihl results in a new risk distribution on high water‐ and flood‐risks. Concluded can be that: The river Delta now is designed for a high water risk that no longer exists. During the majority of the year the water level is very low.
The height-difference between water and city is bridged by a series of staircases that make the space, framed by city and river, accessible for the inhabitants of the surrounding city.
Instead of being read as an addition to the current situation, the staircases become part of the riverbed and form a transition from the smooth cityscape into the lush river, both in material and size. The design allows the riverbed to be used by normal water depth but can also resist occasional high water.
Solving an urban problem on a very detailed scale allows subtle interventions, which find their qualities as humble architectural elements that work as a catalyst to enhance the existing qualities of the existing situation.
The design should also be read as a criticism on the tendency to make the concept behind a design the single most important tool of an architect. Typically the materialization and detailing, which define an important part of the experience of the user, come in a late state of the design. In contrast, in this project, by looking at material and detail parallel to large‐scale concept I hope to improve the symbiotic relationship between urban planning and atmosphere.