## 4 Discussion  
The majority of all the analyzed fishway configurations were proven to have favorable conditions for fish passage, according to [PERSON] et al. 's disorientation and injury boundary biocriteria. In the PO fishways, RSS is correlated with orifice size: all RSS components are observed to increase with the increase of the orifice size, while retaining the same bottom slope and pool length. In the PO fishways with the smallest orifices, almost all RSS values averaged across the pool plane are lower than the disorientation boundary, with two exceptions: \(\tau_{raw}\) on the C plane for i125145 and i100145 configurations. Values of all RSS components are increasing from plane A towards the plane C. An increase in the orifice size to o10 results in the increase of all RSS components across all planes. For this orifice size on the C plane, all RSS components are greater than 20 N/m\({}^{2}\), while \(\tau_{raw}\) is greater than 30 N/m\({}^{2}\) in all configurations. The largest RSS values in the PO-type fishways are recorded for the largest orifice size. For this orifice size on the C plane, all RSS components are greater than 25 N/m\({}^{2}\), while \(\tau_{raw}\) is greater than 30 N/m\({}^{2}\) in all configurations on the C plane and greater than 20 N/m\({}^{2}\) on planes A and B. Overall, the most unfavorable PO fishway configuration is i075145o10, with an average RSS 28 N/m\({}^{2}\), followed closely by the three configurations with a large orifice: i125160o12, i075160o12, and i075190o12. Change in slope and pool length has no significant influence on the change in RSS values. RSS values measured for the VS fishways are larger than the ones measured for their PO counterpart: all RSS components are greater than 20 N/m\({}^{2}\), except for i125145 and i125190. For all configurations, \(\tau_{raw}\) exceeds the disorientation boundary on all planes, with values generally reducing from the top (plane A) towards the bottom (plane C). Overall, the most unfavorable VS fishway configurations are i100160 and i075160, with an average RSS of 41 N/m\({}^{2}\), where \(\tau_{raw}\) exceeds the injury boundary and \(\tau_{raw}\) and \(\tau_{raw}\) exceed the disorientation boundary on planes A and B. In the VS fishways, RSS is inversely correlated with the bottom slope: all RSS components are observed to increase with the decrease of the bottom slope. The greatest change is observed for the transition from i125 to i100, while transition from i100 to i075 is almost negligible. Observed fractions of the RSS values suggest that a large portion of both the main flow jet and recirculation area in the PO fishways satisfy the condition of non-exceedance for disorientation and injury boundary, on average. For all PO fishway types, a fraction of RSS values below the bicoriteria boundaries is inversely correlated with the orifice size, both for the main flow jet zone and recirculation zone. In the main flow jet zone, the largest fraction of the RSS values below the biocoriteria boundaries is concentrated in the shortest pool length for i075 and in the pool 160 for i100 and i125. The smallest fraction of the RSS values below the biocoriteria boundaries is concentrated in the two longest pool lengths (160 and 190) for all slopes. Therefore, it can be considered that the pool length longer than 60 cm does not contribute to the flow environment, except for the largest orifices. It is observed that a fraction of the RSS values below the biocoriteria boundaries is reducing \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & & & & & & & \\ \cline{3-10}
**Fishway** & **Orifice** & & & & & & & & & \\ \cline{3-10}  & & & & & & & & & & \\ \cline{3-10}  & & & & & & & & & & \\ \cline{3-10}  & & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Fraction (%) of the [PERSON]’s shear stress values below disorientation/injury boundary in the recirculation zone. with the increase in the pool length and an increase in the orifice size.