Inherent Damping in a Partially Dry River

As intermittent power sources such as solar power and wind power gains traction in Scandinavia it is likely that the electricity production will become increasingly dependent on hydro power as a buffer in times of power deficit from intermittent power sources due to weather conditions. Rapid changes in hydro power demand can rapidly change the flow conditions in proximity to the power plant. This paper aims to model the transient behavior and quantify the inherent damping in a dry reach in proximity to the largest hydro power plant in Sweden, with respect to production. A two-dimensional model solving the Navier-Stokes equations with shallow water approximations was set up using the open-source solver Delft3D. The Manning numbers in the reach was calibrated with measured steady state water surface elevation data. The simulation data was then validated with transient water level measurements. The results show that it`s possible to calibrate the Manning numbers using steady state water level measurements. The model also shows that it`s possible to capture the inherent damping and more transient behavior using Delft3D. The results can be used to better model rivers without the need for resolving the upstream reach. The results can also be used for ecohydraulical applications where the transient behavior is important.