Climate Change
As most of you know, our global climate is changing. In the Maritimes, we are experiencing more storms, heavier rainfall events, fluctuating seasonal temperatures and shorter, milder winters.
Forest Canopy Protection
Surface water increases with heavy precipitation, especially in areas with hardened surfaces such as pavement, concrete and unvegetated, high traffic hardened surfaces. The ground’s ability to absorb all this water declines when we change the naturally occurring vegetation and tree growth. Forest canopy naturally intercepts the force of heavy rainfall, but deforestation removes this protection. The ground surface is uprooted and many important ecosystems destroyed.
Soil Exposure
The soil is left wounded and exposed. Essential ground cover is removed, which was needed to hold moisture and create arable land. Soils are open to excessive drying from the sun and can quickly become unviable soil. Sediments are easily blown away by wind or washed away by surface water overland flow. The tree canopy provided shade to the forest floor, helping slow the process of evaporation. Entire ecosystems and critters were living in the mossy forest floor. Many animals feed on moss and small invertebrates located within it.
Freeze-Thaw Processes
Another large contributor to damage on your property is freezing and thawing processes above the frost line; the 4 feet directly below ground surface. When the ground freezes, all water within the void spaces of the soil expands. These can be cracks large enough to see on the ground surface or microscopic. When the ground thaws during the warmer days, the ice melts and increases the instability of the land, sometimes allowing it to creep, shift or slump which occurs once the weight of the overburden succumbs to gravity.
Slump
When the bank material has reached its carrying capacity for water and/or the integrity is compromised from slope toe undercutting, the bank may begin to collapse and upland material can slide down the slope face.
Ice Scour
Ice pushes into the shoreline with a force of 10 to 12 tons per square foot. Most northern lakes have permanent coastal damage called ice-shove ridges (Tip of the Mitt Watershed Council, 2007).
Wave energy on ocean and lakefront – water creates significant toe erosion to unconsolidated shorelines. Ice flows lift on top of waves and push into the banks. Scouring the bank occurs and damages vegetation roots; this induces slope erosion and slope instability.
Warmer Winters
Have you noticed the ground isn’t freezing and staying frozen for very long over the winter months? Climate Data for Nova Scotia (2014) shows an increasing amount of Freeze Free Days (shown below) from 1980s to the projected 2080s. Over this century, we will see an increase of 59 more above 0°C days.
Riverbank and Riverbed Erosion
Increased water levels created during spring thaw and heavy rainfall events bring large amounts of water form the upland. When the amount of running water increases, water velocity also increases. The accelerated river water hits the riverbanks with greater force, dislodging tree stumps, rocks, and carrying sediments down the river. The increased volume of water generates stronger currents, enabling more destruction of the riverbed and toe of the bank. Flooding raises the height of the river which promotes sediment removal from higher up on the riverbank.
Coastal Erosion Processes
Storm surge, sea level rise (SLR), wind and waves are all common causes.
Storm surge
occurs when hurricane winds force ocean waves tens of kilometers inland. Storm surge is typically the greatest threat to property and life during a hurricane.
Sea level rise
Along Atlantic Canada is expected to rise even higher than the global average this century. The Intergovernmental Panel on Climate Change (IPCC 2007) predicts sea levels may rise between 60 and 120 cm (2 to 4 feet) in Atlantic Canada in this century. Not only do we face rising sea levels, but the land in the Atlantic region is sinking due to land displacement from the last glaciation. This process is called subsidence, and in the Halifax area, it is calculated to be approximately 1.6 mm per year.
Wind
Displaces unvegetated sediments along coastal shorelines from one place to another. Mass quantities can easily be displaced from beaches and sand dunes. Undercutting of the crest is a massive problem along our Maritime coasts. Once the wind has displaced the underlying soils of banks and cliffs, the crest becomes unstable and unsafe to support weight from the top.
Waves
Produced when wind travels over the surface of a water body. High winds can produce massive waves; during Hurricane Dorion a Newfoundland buoy recorded a peak wave height of 30.7 m (100.7 ft) (Earth Observatory NASA, 2019).
Rills and Gullies
Drainage pathways that are cut into banks from overland flow and upland drainage pathways.
Rills
Shallow channels that occur in soft soils after heavy rainfall over a short amount of time. They measure from 0.7 – 10 centimeters deep and are generally found on poorly vegetated slopes.
Gullies
The product of unattended rills. They measure from 10 to hundreds of centimeters deep. Water always flows towards the path of least resistance – these conduit paths act as the highway for future overland flow. As the size of the rills and gullies increase, the storage capacity for water increases as well as the water velocity. Faster moving water allows for increased sediment transport and deposition. Valuable land is lost from the upland to streams, rivers, lakes, and oceans below, including agricultural chemicals along with it. If rills and gullies are not managed, they continue to expand and make the soil increasingly more unstable.
Helping Nature Heal Can Help!
We cannot stop climate change, but we can help you slow the erosion on your property. With over 21 years of experience restoring ecosystems and helping inspire people to connect with nature. HNH has vast experience with many dynamic environments, none of which are ever the exact same.
Our team has vast knowledge how to start the healing process after erosional processes on your property has occurred using plant-based strategies and natural infrastructure.
The weakest day of our work is on the first day, and from that day forward the plants become established and mature into healthy participants of the ecosystem triangle.
Please visit us at our website Helping Nature Heal for more information. We look forward to helping your nature heal!
Ecological Restoration Intake Form Living Shoreline Intake Form