## 3 Results
The lowest RSS values are concentrated in the A plane  
Figure 5: 3D scatterplot of concurrent RSS components for the i125l45 fishway configuration: (**a**) pool-orifice type fishway and (**b**) vertical slot fishway. for PO fishways with o10 and o12 orifices, but with smaller differences to other planes in comparison to previous configurations. For the o8 orifice, the lowest RSS values are in the B and C plane, not exceeding 14 N/m\({}^{2}\) on average. The largest RSS values are concentrated in the A plane for PO fishways with an o8 orifice above 19 N/m\({}^{2}\) on average, while the maximum value of 37 N/m\({}^{2}\) is observed for the \(\tau_{uw}\) in the C plane under the largest orifice. For VS fishways, RSS values are highest for the A plane (35 N/m\({}^{2}\)), and are reduced towards the C plane (21 N/m\({}^{2}\)). All fishway configurations are characterized with the highest RSS values for o12 orifices, and the lowest for o8 orifices, with VS fishway values higher than all PO fishways. For this configuration, in the vertical slot, fishway values of RSS for the C plane are significantly lower in comparison with the other 2 planes. A reduction in the bottom slope in the shortest fishway (i100l45, Figure 8) and the smallest orifice results in a reduction in the average RSS values in both A and B planes of \(-\)36% and \(-\)25%, respectively, while for the plane C there is no significant difference compared to i125145. A similar trend is visible for the middle orifice size--a reduction in the average RSS values in planes A and B for \(-\)11% and \(-\)23% and no significant change on plane C. The largest orifice has a somewhat different trend: an increase in the average RSS values in planes A and B of +12% and +6% and no significant change in plane C. For VS, fishway increase of the RSS values is uniform at +15% across all planes. The RSS  
Figure 6: 3D scatterplot of concurrent RSS components for the i125l60 fishway configuration: (**a**) pool-office type fishway and (**b**) vertical slot fishway. Figure 7: 3D scatterplot of concurrent RSS components for the i125l90 fishway configuration: (**a**) pool-office type fishway and (**b**) vertical slot fishway. \(\tau_{uw}\) component is higher in comparison to concurrent \(\tau_{uw}\) and \(\tau_{vw}\) by +63% and +54% on average for all orifice sizes. Differences between RSS components in corresponding VS fishways are almost identical to the i125145, at +88% and +86% on average. Concurrent values of \(\tau_{uw}\) and \(\tau_{vw}\) are approximately of the same stress range, with differences between them ranging from \(-\)9% to \(-\)13% in a PO fishway and \(-\)1% in the VS fishway (\(\tau_{uw}<\tau_{vw}\)). The lowest RSS values are concentrated in the A plane for all fishways, increasing towards the C plane. Lowest RSS values are in the A plane, not exceeding 10 N/m\({}^{2}\) for 08 and o10 orifices, and not exceeding 20 N/m\({}^{2}\) for o12 orifices on average. The largest RSS values are concentrated in the C plane, exceeding 20 N/m\({}^{2}\) for all fishways, with values in the PO fishway being o12 and the VS fishway approaching the injury boundary (>47 N/m\({}^{2}\)). The middle VS fishway, regarding both the bottom slope and the pool length (i100l60, Figure 9), presents the second most unfavorable RSS environment of all the analyzed configurations (after i075l60), with an average value of RSS 59 N/m\({}^{2}\), 34 N/m\({}^{2}\) and 31 N/m\({}^{2}\) for \(\tau_{uw}\), \(\tau_{uw}\) and \(\tau_{vw}\) components, respectively. RSS distribution for the VS fishway is uniform across the entire flow depth. Pool length has a significant influence on the RSS in the VS fishway: compared to i100l45, all three RSS components are increased on average by +59%. On the other hand, the influence of the larger pool in the PO fishway in comparison to i100l45 is negligible, with a difference in the RSS values <10% for all orifice sizes. The most notable influence of pool length is observed for o8, with average RSS values reduced by \(-\)30%.