MANAGEMENT of RIVER CONTROL STRUCTURES

In the Pacific Region, the Waterways Program maintains 17 river training structures on the lower Fraser and an additional 4 structures on the Harrison River. Many of these structures, originally built at the turn of the century, were designed to stabilize the main channel, improve navigation and reduce channel maintenance costs.

The structures form an integral part of the overall channel maintenance strategy, and are a cost effective alternative to long term dredging. The structures are river training works engineered to direct river flow towards the navigation channel causing a natural deepening of the bottom by using the river's own energy to scour the riverbed to a new designed depth and equilibrium.

Hydraulic models are used to help in the design of the proposed structure and to study their effect on the river. This involves: Constructing a scaled model to represent a section of the river. Calibrating the model by operating it with historical discharges and tidal cycles until the historical patterns of sedimentation are observed, then installing the proposed control structure and operating the model until the optimum configuration and alignment for the structure is found to reduce sedimentation. River discharges and tides are computer controlled based on historical measurements. The movement of sediment, which in the river is sand and silt, is modeled by using crushed walnut shells.