Investigation of Sediment Transport Through a Run-of-River Hydroelectric Project

Author: Violeta Martin, Ph.D., P.Eng., Michael Pullinger, M.Sc., P.Eng., Alana Shewan, M.A.Sc., P.Eng., Nathan Smith, P.Eng.
Conference: HydroVision International 2014
Date: July 22-25, 2014

A 25 MW run-of-river hydroelectric project is proposed in coastal British Columbia, Canada. Baseline studies identified that the bedload sediment transport rate in the project area is relatively low, and consequently, interruption of bed material replenishment in the reaches downstream of the intake represents an environmental concern.

A prerequisite for the successful design of the proposed project includes passing of the spawning size gravel through the intake facility during the period of headpond sediment infilling. A sluice gate has been incorporated in the intake structure to enable the sluicing of sediment. Numerical modelling was undertaken to aid with the intake design and to determine the sediment transport efficiency through the headpond. Hydrodynamic modelling techniques (1D, 2D and CFD) were combined to assess the proposed design and provide an overview of water depths, velocities and bed shear stresses along with the potential for gravel mobility through the headpond reach both before and after the construction of the intake.