Building of a fish pass designed as bottom ramp and slope with embedded boulder bars
Ropa River – km 32+300,
Planned term of start:
Ist quarter 2019
Planned term of end:
IVth quarter 2019
1 870 761 Polish zloty
Why do we interfere in a river?
The aim of the weir is a maintenance of the constant level of damming up for the water uptake located above for industrial purposes. The weir is now an impenetrable obstacle for aquatic organisms. Fish pass existing at the structure doesn’t fulfill the task therefore building of a new one with appropriate parameters is necessary.
The weir damming of water consists of three sections. From the left bank there are two sections separated by a pillar, equipped with bars. A fixed part of the weir (from the right bank) constitutes a concrete threshold which is 18 m long. It dams water up to about 1,5 m. In this part of the weir a chamber fish pass is located. One of the reasons it doesn’t work efficiently is too big water turbulence in chambers.
A modernization of the weir assumes liquidation of the old fish pass and building of a new one in the place of an old overflow. A new fish pass will be designed as a bottom ramp and a slope with embedded boulder bars. It will be separated by a retaining wall from this part of a riverbed which serves as a water intake.
The length of the planned bottom ramp and the slope is 42 m which includes 4 m pools with partitions made by stones of different sizes. Below the bottom ramp and slope, a bottom roughness will be additionally increased by 15 m stone ramp (stilling basin).