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Nature-like fish passage with riprap in periodic rows

It is stated on p.16 of the design guide for nature-like fishways (Larinier et al., 2006)1 that rock-rigged fishways in periodic rows are similar to fish ladders, and their design criteria are identical to those of.

It is therefore possible to use the various tools in the "fish ladder" module module to design this type of device. In particular, the "cloisons" tool can be used to enter the various dimensional characteristics of weirs (widths, overflow dimensions) and pseudo-basins pseudo-basins (length, width, mid-radius), which can be used to indirectly indirectly retrieve the sill height (\(p\)) and useful block height (\(k\)) parameters in the generated geometry table. Porosity (ratio between the free passage between the blocks and the total width width of the pseudo-wall) is not entered directly, but this parameter can be be deduced and examined elsewhere if necessary.

According to this principle, each overhanging portion of the partition must be entered as an indentation or slot, as well as the dimension of the top of the blocks if the latter are flooded within the operating range of the device. In the case of notches, particular attention should be paid to the type of (thick or thin) in order to accurately reflect the conditions of flooding by the downstream of the weir.

It is also possible to use the "pre-dams" tool (the equations implemented are the same as in the "cloisons" tool), if the device is affected by complex feed modes, with, for example, overflows from the weir to different basins in the system (a less frequent case for a riprap pass in periodic rows).

An example of a pass can be accessed directly via this link.

  1. Larinier, Michel, Dominique Courret, et Peggy Gomes. 2006. « Guide technique pour la conception des passes à poissons “naturelles” ». Rapport GHAPPE RA. Compagnie Nationale du Rhône / Agence de l’Eau Adour Garonne.