Application of managed dyke realignment and hydrodynamic modelling for flood mitigation in Truro, Nova Scotia

Abstract

Managed dyke realignment (MR) is to be implemented at a 92-hectare restoration site in the Salmon River Estuary to restore tidal wetland habitat and to help mitigate flooding in Truro. This research examines the accuracy of a hydrodynamic model, predicted flooding within the restoration site and the estuary’s response to MR. Field surveys were conducted to update river bathymetry, and water level and current measurements were collected over several tidal cycles for model calibration and validation. The model successfully reproduced measured water levels, the timing of tides and the tidally-dominated velocity profiles in the channel compared to the field measurements. Modelled water levels in the channel decreased by up to 31.9 cm under the MR scenario, indicating the potential for flood reduction in Truro. The predicted spreading of slow-moving floodwater within the site suggests the potential for net sedimentation followed by halophytic vegetation establishment, indicating net positive benefits of MR.