Paris "Forum des Halles" stormwater Waterfall

Hydraulic operation of the "Canopy" waterfall

Client: SemPariSeine - Scale: 1/3.66


In the context of the redevelopment of the Forum des Halles shopping center in Paris, a curved roof called the “Canopy” was built. This roof consists of 15 transversal storm drains that collect rainwater and discharge it in the form of a waterfall. When the weather is dry, this waterfall may be fed using a closed recrculation circuit, thereby forming a fountain.

Overview of the waterfall model
Overview of the waterfall model












Aims of the physical scale model

The aim of the physical model is to check the hydraulic operation of this structure. The water collected by the different storm drains is concentrated inside a main collector which downstream end constitutes the inlet to the waterfall. Different specific issues must be checked and optimised:

  • hydraulic flow conditions in the collector and during injection of the flow from each storm drain,
  • flow conditions in the weep hole and at the inlet of the waterfall,
  • trajectory of the waterfall and water collection conditions in the basin located at the waterfall foot.

Model of the collector and gutters of the Canopy
Collector and gutters

Description of the physical scale model

The model was developed to accurately represent flows inside the main collector and in the downstream sections of each of the five last storm drains. The waterfall and its collection basin area were also represented at scale in order to visualise the quality of flows in the waterfall and the trajectory of the water.