Efficiency Improvements of Step-Pool Channel

This paper describes the monitoring of the operation of a rough-channel pool fish-pass conducted at the hydropower plant "Bukówka on the River Neisse, Poland. Initial observations showed that the fish come to the fishway, but do not pass it. The cause for this was the excessive speed of the water, reaching over 2.5 m / s, and the highly turbulent nature of its flow. The coefficient of energy dissipation in the chambers averaged 367 W/m3 (155-911). We reduced water flow by reducing the gate's opening at the top of the fishway. Flow velocity decreased at the gate, taking a maximum value of slightly more than 1.5 m / s. The coefficient of energy dissipation in the chambers decreased to an average of 320 W/m3 (134-809), but still stayed well above the critical value limiting the fish migration. Despite this, after a reduction of inflow we found few individuals  of roach (2), chub (2) and  perch (1) in the trap placed at the exit of the fishway. Also the fish appeared much more numerous along the entire length. As a next step we plan to construct additional flumes and increase the elevation of some parts of the fishways. This will reduce the slope of ladders of the fishway, which, combined with adjustable flow rates will allow the calming flow of water. The proposed changes will lead to a significant reduction in the energy dissipation rate in the chambers - an average of 90 W/m3 (11-169). Another improvement will be its change in direction of the attraction flow  90 º to 30 º.