Sediments removed by reservoir flushing above run-of-river stations tend to settle immediately downstream of the dam. Sediment remaining near the turbine outlets raises the water level and thus reduces the head available for power generation. In addition, this interrupts the natural process of sediment transport, making it difficult to accomplish a good ecological status as defined in the EU Water Framework Directive.
The aim of our research project is to increase the flow velocity in the critical area in order to wash the sediments further downstream. One possible solution is to lengthen the downstream pier between the spillway and turbine bays. The lengthened pier prevents the sediments from settling immediately downstream of the turbine outlets, with the disadvantage, however, of having an unfavourable effect on the flow in this area. So optimal adjustment to the great variety of operating conditions at a run-of-river station is needed. We have solved this problem mainly by providing a dividing pier of variable height. We plan to translate this idea into reality by a novel, economical, and robust design. The results from our studies will form the basis for a pilot project intended to demonstrate how this system works in practice.