Hydraulic Assessment of the Ganaraska River, Port Hope, Ontario

Abstract

The existing hydrologic model of the Ganaraska River Watershed, developed about twenty years ago, and the Regulatory Flood, estimated using that model, was not considered reflective of current watershed conditions by the Ganaraska River Conservation Authority (GRCA). Also, the Cameco Corporation property near the mouth of the Ganaraska River is potentially affected by the Regulatory Flood limit and the Corporation, therefore, had an interest in accurately defining the Regulatory Flood limit. The GRCA and Cameco agreed to address the necessary technical update with two studies-a hydrology study prepared by the GRCA with the assistance of Schaeffers Consulting Engineers and a hydraulics study prepared by Cameco Corporation with the assistance of AMEC. The peak flow estimates computed with the newly developed hydrologic model, a component deliverable of the recently completed hydrology study, changed from those previously generated using the 1980's vintage simulation model. Therefore, there was a need to update the present Regulatory Flood Plain delineation and mapping to reflect the new flood flow estimates. The objective of this study was to undertake a hydraulic assessment of the Ganaraska River from the mouth of the river at Lake Ontario to the Robertson Street Bridge, as illustrated in Figure 4.1, and to compute the water levels for the purposes of identifying flood proofing elevations for the Cameco site.