Coastal Erosion Protection Systems

Understanding Coastal Erosion in Atlantic Canada

Atlantic Canada's 42,000 kilometres of coastline face relentless assault from rising sea levels, intensifying storm activity, and natural geological processes. For communities throughout Nova Scotia, New Brunswick, Prince Edward Island, and Newfoundland and Labrador, coastal erosion represents not merely an environmental concern but an existential threat to infrastructure, property, and economic vitality. The Bay of Fundy region, home to the world's highest tides reaching up to 16 metres, presents particularly unique engineering challenges that demand sophisticated protection systems.

In Nova Scotia alone, approximately 70 percent of the provincial coastline experiences some degree of erosion, with average recession rates ranging from 0.5 to 1.5 metres annually in vulnerable areas. Certain locations along the Northumberland Strait and Cape Breton's eastern shore have documented erosion rates exceeding 3 metres per year during severe storm seasons. These statistics underscore the critical importance of implementing robust coastal erosion protection systems designed specifically for Maritime conditions.

Understanding the mechanisms driving coastal erosion is essential for selecting appropriate protection strategies. In our region, the primary erosive forces include hydraulic action from wave impact, abrasion from sediment-laden water, freeze-thaw cycles unique to our northern climate, and the increasingly significant effects of sea-level rise projected to reach 0.75 to 1.0 metres by 2100 along Nova Scotia's coastline.

Hard Engineering Solutions for Coastal Protection

Hard engineering approaches utilise permanent structures constructed from durable materials to directly resist erosive forces. These solutions remain essential components of comprehensive coastal protection strategies, particularly for safeguarding critical infrastructure, industrial facilities, and densely developed waterfront areas throughout Atlantic Canada.

Seawalls and Revetments

Seawalls represent the most substantial form of coastal defence, typically constructed from reinforced concrete, steel sheet piling, or engineered concrete block systems. Modern seawall designs for Maritime applications must account for ice loading pressures that can exceed 150 kilopascals, wave impact forces reaching 50 to 100 kilonewtons per square metre during major storms, and the corrosive effects of salt water on structural materials.

Revetments offer a more economical alternative, consisting of sloped armour layers that dissipate wave energy rather than reflecting it. Common materials include:

• Rip-rap stone: Typically granite or basalt in the 1 to 5 tonne range for primary armour layers

• Concrete armour units: Including tetrapods, dolosse, and Core-Loc units weighing 2 to 20 tonnes each

• Gabion baskets: Wire mesh containers filled with stone, suitable for moderate wave environments

• Articulated concrete block mats: Interlocking systems providing flexibility while maintaining structural integrity

Design specifications for revetments in Nova Scotia typically require armour stone density exceeding 2,600 kilograms per cubic metre, with filter layer gradations carefully calculated to prevent substrate erosion while allowing proper drainage. The slope angle, generally ranging from 1.5:1 to 3:1 horizontal to vertical, must be optimised based on local wave climate data and available materials.

Breakwaters and Groynes

Breakwaters serve to reduce wave energy before it reaches the shoreline, creating sheltered areas that promote sediment deposition. Rubble mound breakwaters, the most common type in Atlantic Canadian harbours, typically feature a core of quarry run material overlaid with progressively larger stone layers culminating in primary armour units. Design wave heights for exposed Nova Scotia locations often exceed 8 metres, requiring careful attention to crest elevation and armour stability calculations.

Groynes extend perpendicular to the shoreline, interrupting longshore sediment transport to build up beaches on their updrift side. In the Maritime context, groyne fields must be designed considering predominant wave directions from the northeast and southeast quadrants, with typical spacing of 1.5 to 3 times the groyne length. Timber groynes remain common for smaller-scale applications, though rock and concrete structures offer superior longevity for permanent installations.

Soft Engineering and Nature-Based Solutions

Increasingly, coastal engineers recognise the value of working with natural processes rather than against them. Soft engineering approaches offer environmental benefits, reduced long-term maintenance costs, and often superior adaptation to changing conditions—particularly relevant given climate change uncertainties affecting Atlantic Canada.

Beach Nourishment Programs

Beach nourishment involves the placement of compatible sediment to restore eroded beaches and maintain protective buffer zones. Successful projects in the Maritimes require careful sediment analysis to match grain size distributions, mineralogy, and colour characteristics with native beach material. Typical specifications call for median grain diameters within 10 to 20 percent of existing sediment, with minimal fines content below 5 percent to prevent rapid winnowing.

Initial nourishment volumes generally range from 100 to 500 cubic metres per linear metre of shoreline, with anticipated re-nourishment cycles of 5 to 15 years depending on exposure and sediment characteristics. While aggregate costs may exceed hard structures over extended timeframes, beach nourishment provides recreational benefits and maintains natural coastal processes that hard structures often disrupt.

Living Shorelines and Vegetative Stabilisation

Living shoreline approaches integrate biological elements with structural components to create resilient, self-maintaining coastal protection systems. In Nova Scotia's varied coastal environments, these techniques may incorporate:

• Salt marsh restoration: Establishing Spartina alterniflora and Spartina patens communities that attenuate wave energy and trap sediment

• Dune reconstruction: Building and stabilising coastal dunes with American beach grass (Ammophila breviligulata) plantings

• Oyster reef construction: Creating subtidal breakwater structures that provide habitat while reducing wave energy

• Riparian buffer establishment: Planting native shrubs and trees to stabilise upper bank areas

Research conducted along the Northumberland Strait demonstrates that healthy salt marshes can reduce wave heights by 50 to 90 percent over distances of 20 to 40 metres, while simultaneously sequestering carbon and providing critical habitat for commercially important species including Atlantic lobster and various finfish.

Hybrid Protection Systems

Contemporary coastal engineering practice increasingly favours hybrid approaches that combine hard and soft elements to maximise protection while minimising environmental impact. These integrated systems prove particularly effective for Atlantic Canada's dynamic coastal environments, where conditions vary dramatically between seasons and storm events.

A typical hybrid system might incorporate a rock sill or low-profile breakwater to reduce wave energy reaching the shore, combined with beach nourishment and vegetation planting in the protected zone. This approach provides immediate structural protection while allowing natural processes to establish longer-term resilience. Design considerations must address the transition zones between hard and soft elements, where scour and erosion concentrations commonly develop without proper engineering.

Advanced hybrid designs may also incorporate engineered elements such as geotextile containers filled with sand or dredged material, providing structural mass while remaining more adaptable than rigid concrete structures. These systems can be designed for controlled deformation under extreme loading, preventing catastrophic failure while maintaining overall protective function.

Site Assessment and Engineering Design Process

Effective coastal protection requires comprehensive site characterisation and rigorous engineering analysis. The design process for erosion protection systems in Nova Scotia must address numerous technical parameters and regulatory requirements specific to our jurisdiction.

Data Collection Requirements

Essential baseline data for coastal protection design includes:

• Topographic and bathymetric surveys: Extending from the upland area through the nearshore zone, with vertical accuracy of ±5 centimetres or better

• Geotechnical investigations: Including borehole logs, soil classifications, and strength testing for foundation design

• Wave climate analysis: Utilising hindcast data, nearshore transformation modelling, and extreme value statistics for design wave determination

• Water level records: Incorporating tidal ranges, storm surge history, and projected sea-level rise scenarios

• Sediment transport assessment: Quantifying longshore drift rates, sources, and sinks within the coastal cell

• Historical shoreline change analysis: Using aerial photography, satellite imagery, and survey records spanning multiple decades

Regulatory Framework and Approvals

Coastal protection projects in Nova Scotia require coordination with multiple regulatory agencies. Provincial approval under the Environment Act is typically required for works below the ordinary high water mark, while federal authorisation under the Fisheries Act and Canadian Navigable Waters Act may apply depending on project scope and location. The provincial Coastal Protection Act, enacted in 2019, establishes additional requirements for development in designated coastal protection zones.

Environmental impact assessment requirements vary with project scale, though all marine works must consider potential effects on fish habitat, water quality, and species at risk. Consultation with Mi'kmaq communities is increasingly required for projects affecting traditional territories and resources, reflecting the province's commitment to reconciliation and Indigenous rights recognition.

Climate Change Adaptation Considerations

Coastal protection systems designed today must perform adequately throughout their intended service life under conditions significantly different from historical norms. For major structures with 50 to 100-year design lives, climate change adaptation represents a fundamental engineering requirement rather than an optional enhancement.

Key adaptation parameters for Atlantic Canadian coastal projects include:

• Sea-level rise allowances: Current provincial guidance recommends incorporating 0.7 to 1.0 metres of additional freeboard for permanent structures

• Increased storm intensity: Design wave heights should reflect projected increases in extreme storm frequency and severity

• Changed precipitation patterns: Drainage and overtopping calculations must account for more intense rainfall events

• Extended ice-free seasons: Reduced winter ice cover may increase erosion during traditional low-activity periods

• Adaptive management provisions: Designs should incorporate options for future modification or enhancement as conditions evolve

The concept of adaptive pathways planning is gaining traction in Maritime coastal management, acknowledging that optimal protection strategies may change as sea levels rise and storm patterns shift. Initial investments in flexible, adaptable systems often prove more cost-effective than rigid structures requiring complete replacement when design conditions are exceeded.

Maintenance, Monitoring, and Asset Management

Coastal protection structures require ongoing attention to maintain their protective function throughout their service life. In Atlantic Canada's challenging environment, where structures endure ice impact, severe storms, and significant temperature variations, proactive maintenance programmes are essential for protecting capital investments.

Recommended monitoring activities include annual inspections following the ice season and major storms, periodic surveying to document settlement, displacement, or damage to structural elements, and regular assessment of adjacent shoreline changes that may indicate altered sediment transport patterns. For critical infrastructure protection, instrumented monitoring systems can provide real-time alerts when structure performance parameters exceed acceptable thresholds.

Asset management planning should incorporate life-cycle cost analysis, comparing initial construction costs against anticipated maintenance expenditures, eventual rehabilitation requirements, and ultimate replacement needs. While hard structures typically require 15 to 25 percent of initial costs for maintenance over their service life, soft engineering approaches may demand more frequent intervention but at lower individual cost per event.

Partner with Experienced Coastal Engineering Professionals

Protecting Nova Scotia's coastline requires specialised expertise in marine engineering, geotechnical analysis, environmental science, and regulatory navigation. The complexity of coastal processes and the consequences of inadequate protection demand professional engineering services from firms with demonstrated experience in Atlantic Canadian conditions.

Sangster Engineering Ltd. brings decades of Maritime engineering experience to coastal protection challenges throughout Nova Scotia and the broader Atlantic region. Our professional engineers understand the unique combination of tidal influences, ice conditions, and storm exposure that characterises our coastline, and we apply this knowledge to develop practical, cost-effective protection solutions tailored to each client's specific needs.

Whether you require assessment of existing coastal structures, design of new protection systems, regulatory approval support, or expert guidance on climate change adaptation strategies, our team provides comprehensive engineering services from initial consultation through construction oversight and beyond. We work closely with property owners, municipalities, industrial clients, and government agencies to deliver coastal protection solutions that safeguard investments while respecting environmental values.

Contact Sangster Engineering Ltd. in Amherst, Nova Scotia, to discuss your coastal erosion protection requirements. Our experienced team is ready to help you develop sustainable solutions for protecting your waterfront assets against the challenges of today and the uncertainties of tomorrow.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.