Small Craft Harbour Design: Engineering Methods and Insights to Improving Functionality, Maintenance and Safety of Existing and new SCH Facilities in Atlantic Canada​

The southwest coast of Nova Scotia is home to many harbours maintained by Canada’s Department of Fisheries and Oceans (DFO) that are vital to the local fishing industry. North Atlantic swells and long waves pose challenges... [ view full abstract ]

The southwest coast of Nova Scotia is home to many harbours maintained by Canada’s Department of Fisheries and Oceans (DFO) that are vital to the local fishing industry. North Atlantic swells and long waves pose challenges for harbour retrofit and expansions, requiring detailed study of the agitation processes to support coastal infrastructure design. Since 2014, arrays of high frequency sampling wave gauges were deployed at harbours throughout Nova Scotia to monitor the nearshore outer-harbour wave climate and its impact on the mooring basins.

Most literature case studies of harbour oscillations include large ports, with fewer examples of observations at small craft harbours. Small scale semi-closed harbour basins have natural resonant period of typically a few minutes which can cause problematic oscillations, triggered by low-frequency infragravity waves, unique bathymetric conditions, basin geometry and atmospheric forcing. Long wave forcing were detected at all the studied sites, with varying impacts, such as vessel agitation or scour-inducing currents.

The new set of field observations was used to calibrate high resolution Boussinesq wave models of the harbours. The models were used to design improved harbour retrofit and expansions. Lessons learned include: (1) The intensity and peak period of long wave energy is highly variable even within the relatively small geographical area of SW NS, (2) natural harbour resonance frequencies can be reasonably predicted based on basin size, (3) adequate scour protection along the harbour entrance may be critical, (4) mitigating existing resonance may require substantial rearrangement of the harbour layout.