Shoreline erosion and relative sea level rise are increasing the risk of flooding and storm damage to Highway 2 as it approaches the Town of Souris. Climate change with the associated rising sea levels, reduced ice cover and changing storm patterns threatens to exacerbate this problem. In order to improve protection of Highway 2, PEI Transportation Infrastructure and Energy (PEI-TIE) worked with Coldwater Consulting Ltd. to develop and construct a two-part shore protection scheme that combined hard protection for the highway infrastructure with beach restoration works to improve the resilience of the beach and dune system. The beach restoration works included the construction of two _INTER-TIDAL REEFS_.
This is the first time that inter-tidal reefs have been used on the Island. An example of 'building with nature', the sandstone reef structures provide two primary functions: wave attenuation, dampening the effects of storm waves on the beach area and highway infrastructure; and, creating an area of calmer water on the landward side of the reefs where sand that is moving along the shore area will slow down and deposit and, over time, accumulate and cause the beach to grow / extend offshore towards the reefs. The result is increased beach width and protection of the dunes and coastal / highway infrastructure. The use of PEI sandstone for the reefs provides a natural marine substrate for the development of benthic flora and inter-tidal pools.
It also offers the aesthetic benefit of blending-in with the exposed sandstone found elsewhere along the coast. While not as durable as, say, concrete or imported granite, the sandstone is locally available (reduced haulage costs and associated CO2 emissions) and, will eventually break down into beach sand. The project has been undertaken as a demonstration project, with the financial support being shared between the Province of Prince Edward Island and the federal government through Public Safety Canada’s Natural Disaster Mitigation Program. The project is consistent with ‘adaptation’ principles outlined in the Province’s Climate Change Strategy, and the intent is to demonstrate techniques for the protection of coastal infrastructure against flooding and erosion hazards through the use of nature-based design principles.
The project was completed in early 2018 and a monitoring program has been implemented to document shoreline conditions using both RTK-GPS surveys and drone-based ortho-photogrammetry. Monitoring to date is showing that beach changes are consistent with the numerical modelling predictions used in the design process.