Dam canoe pass
A canoe pass is a structure that enables leisure watercraft, such as canoe-kayaks and rafts, to bypass dams.
The various passes
Several different types of canoe pass exist depending on the type of use (type of watercraft, level of skill, etc.), the site’s characteristics (topography, hydrology, land, etc.) and the obstacle to be bypassed :
- slide (fixed or on floats) : a slide is a smooth-bottomed canoe pass whose cross-section is generally almost a semi-circle,
- baffle pass: baffles are inserted into the bottom of the canoe pass to reduce flow velocity and maintain a sufficient blade of water to allow watercraft to slide. There are different types of baffle (made out of wood, steel or plastic). Polyethylene thermoformed baffles offer a safe, functional and economic solution that is easy to install.
- bypass channel: a linear canoe pass whose length can vary and that is similar to a river; it may comprise embedded sills to make up for the height difference,
- pre-barrages or pool-and-weir passes: the fall to be crossed is divided into several small falls thanks to a series of pseudo-pools that dissipate energy. The sills, which often consist of triangular notches, take various factors (draught, width, etc.) into account to enable watercraft to pass over them.
Certain types of canoe pass can also be used by certain species of fish (depending on the target species); they are known as ‘mixed passes’ (baffle passes, bypass channels and pool-and-weir passes).
For each site, a specific study must be carried out to identify the type of pass, the installation of the pass and the technical characteristics of the pass so that the structure may be cleared as safely as possible.
