The present invention comprises a fish guidance rack (2) for use in a fish guidance system in a watercourse (W) at a run-of-river hydropower plant or a water intake. The rack comprises a series of vertical bars (1) mounted on a rack frame (7) along a longitudinal axis (L) of the rack between a first end (5) of the rack and a second end (6) of the rack. The rack comprises bars with a hydrodynamic curved form, and a generally increasing inter-bar spacing (sb) in the downstream direction.

A flood protection system (10) on a watercourse (16) with a flood-prone area (18) includes a main pipe (12) along the watercourse (16) in this flood-prone area (18). At least parts of the watercourse (16) are guided through the main pipe (12) in the direction of flow (28). A drive turbine (62) in the main pipe (12) increases the flow velocity of the flowing water (16) in the main pipe (12) in the event of flooding, the main pipe (12) flowing back into the flowing water (16).

The fish screen for a suction strainer includes at least one first plate having a central opening formed therethrough, a second plate, a helical spring, and a mesh bag. The helical spring has opposed first and second ends, with the first end secured to the at least one first plate and the second end secured to the second plate. The helical spring has first and second portions positioned respectively adjacent to the first and second ends. The second portion has a smaller diameter than a diameter of the first portion. The mesh bag releasably and removably covers and receives the at least one first plate, the second plate and the helical spring. The second portion of the helical spring is adapted for releasably holding a free end of a suction strainer received within an interior of the helical spring through the central opening of the at least one first plate.