4.5. Dimensionless discharge equations for the main fishway types

As stated earlier, the model parameters obtained depend on the data used in creating equations for dimensionless discharges by the fitting curves. Thus, the parameters can, to a some extent, be freely chosen without causing too large an error, or an error that can be adequately proved. For this reason, equations for dimensionless discharges in the three main fishway types are given in Table 7. The equations can be applied in fishway designing processes, keeping in mind that in the normal range of dimensionless water depths y_o/L, pool-and- weir fishways are sensitive to changes in model parameters. This means that a small change in model parameters gives a significant change in dimensionless discharges and water depths. In vertical slot and Denil fishways, the change is not as great. In addition, it should be kept in mind that the dimensionless discharge values and the respective dimensionless water depths describe the situation inside the fishway, in the region of fully developed flow. These equations do not give the relation between the upper water level and fishway discharge.

Table 7. Suggested dimensionless discharge equations for different fishway types with Equation (22) used for scaling discharges and the distance between the weirs used for scaling lengths.

Fishway model	Scaling factor	Dimensionless discharge equation
Vertical slot fishway
Denil fishway
Pool-and-weir fishway