Explore the topics below to learn how coastal processes can put our Great Lakes communities at risk.
A littoral cell is a stretch of coastline, often over 100 km long, where sand circulates. Coastal processes like bluff erosion and periods of high-water levels transport sediment along the littoral cell. Sediment, a mixture of sand, clay and silt, falls from bluffs and/or banks to the beach and is picked up, transported and deposited by the littoral drift.
Depending on where a property sits within a littoral cell, it may be in an up-drift or down-drift area. Coastal structures, including armoured coastlines, breakwaters or harbours, can disrupt this natural flow, causing sediment to build up down-drift, while up-drift areas lose sand, leading to accelerated erosion and beach loss.
Coastal erosion is a natural process that shapes and maintains the coastline and beaches across the Great Lakes. Extreme winds, waves, rainfall, and surface runoff can accelerate sediment transportation and erosion rates. Coastal erosion becomes hazardous when it destabilizes slopes and threatens built infrastructure.
When lake levels rise significantly above their normal range, due to heavy rainfall or snowmelt, waves reach farther inland, flooding dunes and stripping away the vegetation that protects the coast. As a result, low-lying areas, homes, and infrastructure become more vulnerable to storm damage and erosion.
Low lake levels expose the lakebed to erosion from waves and wind, forming deep divots known as lakebed erosion. During storms, intense wind-driven waves hit the coastline, pushing lake water inland, this is known as wave uprush and overtopping.
Ice cover acts like a shield, protecting the coast from winter storms, reducing erosion. Without it, wave uprush hits the coast with full force increasing the risk of damage.
During winters with minimal ice cover, coastlines are exposed to intense waves and ice spray. Erosion worsens, and ice spray coats roads and homes in thick ice.
