Abstract
Current measurement in the river Dalälven, situated in Sweden, was compared with flow values. These were also used to validate a numerical simulation of the channel. The results showed the numerical program was able to assess the current speed variations, but the magnitude of the current speed was slightly lower than the measured values, a possible effect of bathymetry errors. The water level variations were not correctly assessed, which is probably due to that wind data was excluded.
The numerical program was used to evaluate how large the effects on the surrounding water level and current speed can be for a set of ten turbines distributed evenly along the channel. To investigate how the hydrography of the channel is affected by energy extraction, a set of ten turbines distributed evenly along the channel were put into the numerical model. It showed that extracting 75 kW would increase the water level at the power station (upstreams) from the level at the same place without any turbines with 5.5%, and 135 kW would lead to an 8.8% increase, assuming a constant water level at the downstream boundary. With increasing cd-values, the velocity around the turbines increases, while it decreases at the turbine.