Assessment of Tidal Stream Energy Resources in a Hypertidal Estuary with a Highly Irregular Bathymetry using a 3D Numerical Modelling

The overall goal of this paper is to assess the hydrokinetic potential of in-stream tidal energy in the Koksoak River Estuary (KRE) using a new approach. The KRE is a hypertidal estuary with the maximum tidal range of 13.9 m at its mouth. The reach has also an extremely irregular bathymetry on its downstream side. These bathymetric and hydrodynamics features could provide a substantial source of tidal energy for the isolated off-grid communities developed around this river. In this paper, multilevel modelling was employed to characterize hydrodynamic of the estuary and to compensate for the influence of data deficit. Using the Delft-3D suite, a 3D flow model was implemented and well calibrated against the available water level data. To improve the model performance, different scenarios for bed roughness coefficient (Manning coefficient) were considered and their corresponding water level time series at the calibration point was extracted. Then, the Bayesian Model Averaging (BMA), that is an ensemble forecasting approach, was used to combine best aspects of each competing scenarios. Results of optimized model based on BMA method showed a considerable improvement on model predictions. Finally, based on the optimized model, the hydrokinetic potential of the Koksoak River on its estuarine region has been estimated over a 14-days tidal cycle. Results have shown that 2 large farms of hydrokinetic energy are available in the system with the mean power density of about 6.8 and 6.5 kW/ m², which is an outstanding potential in the tidal stream power category.