Green Infrastructure Innovation Captures up to 98% of Sediment in Coastal Erosion

Emillie Rose

Figure 1. Soil stabilization, Prince Edward Island (PEI) (2022). Photo credit: Helping Nature Heal.
Figure 1. Soil stabilization, Prince Edward Island (PEI) (2022). Photo credit: Helping Nature Heal.

Sustainability Through Innovation

This article is part of Environmental Connection’s mission to help grow the industry by promoting innovative research, products and
technology that meet industry needs through more sustainable approaches. Articles in future issues will continue to provide multiple
perspectives to promote ongoing efforts to protect natural resources.

The Atlantic shores on the Eastern side of North America face particular challenges due to climate change and sea-level rise. Canada is expected to warm at nearly twice the global rate, and significant storm events are happening with greater frequency and intensity. Due to land subsidence, or the sinking of the coastline due to the last glaciation, the relative sea-level change is expected to be higher than the global average in the Atlantic region, with a rise of 60 to 100 cm (24 to 40 inches) predicted.

The shorelines are particularly vulnerable to erosion. Thousands of public and private properties are already being affected along Atlantic coastal communities. Erosion rates for coastal bluffs in Nova Scotia are as high as 10 m (11 yards) per year for newly exposed headlands.1 Sea-level rise and increasing storm intensity are accelerating coastal erosion.

Coastlines are dynamic, living ecosystems that transform naturally through erosion, sediment transport and deposition. While many landowners build hard armour walls to protect individual properties from erosion, this grey infrastructure comes with high costs, ecosystem damage, biodiversity loss and limited efficacy.

Helping Nature Heal (HNH) is an ecological restoration company based in Nova Scotia, Canada. They work with nature to restore living shorelines (Figure 1). HNH was driven by the challenge of effectively addressing coastal erosion using a sustainable green infrastructure alternative to hard armour, which presents secondary effects.

This challenge has led to the development of Living Shorelines, which is a three-part method for coastal protection that has resulted in up to 98% sediment capture. Living Shorelines is a soft engineering approach to mitigate the effects of erosion on waterfront property without endangering the coastal ecosystem (Figure 2). It includes:

  • Application of condition-specific native plant companion groupings.
  • Low-tech green techniques for planting on steep and eroding slopes.
  • A plant nutrition product, Abundance root booster, that stimulates root growth. This 100% natural organic soil booster fosters healthier root systems, showcased through increased root diameter and length, reduces the rate of erosion to 1% to 2% of previous sediment runoff and enhances the resilience of coastal areas.

HNH designs condition-specific native plant groupings for each job, with the goal of optimizing healthy, rapid and dense root development. Factors are considered such as soil composition, incoming energy (solar, wind, water, etc.) and plant species characteristics. Each design specifies the plant species, groupings and density that will be most resilient to change, even when challenged by climate issues.

Over hundreds of projects, a series of low-tech, low-cost green techniques were developed and refined for planting on steep and eroding slopes, such as those in Prince Edward Island (Figures 1 and 3). Erosion chevrons, wattle fencing and veggie groynes are a few of the methods used to successfully establish plantings in very challenging terrain conditions. These methods add no inorganic materials to the site, which prevents pollution and allows the site to re-naturalize with minimal further intervention (Figure 3).

Abundance is an all-natural concentrate root booster that helps plants establish new roots, reduces transplant shock and plant loss, permanently improves nutrient and water uptake, and permanently improves disease resistance. It is applied in all Living Shorelines
and other restoration projects and is also provided as a standalone product.

Abundance is enriched with essential nutrients and minerals from land and sea. This award-winning soil booster ensures that plants thrive naturally. It won the Kelp Fest 2024 Product Award from the Ecology Action Centre.

The formulation includes kelp iodine concentrate (typically 50 ppm/L or 50 mg/L) with over 70 minerals, vitamins, trace elements, amino acids and citric acid. The produce is specifically formulated with mycorrhizal fungi and beneficial bacteria, with total nitrogen 11%, available phosphate 0.5% and soluble potash 7%. It is 100% biodegradable.

Figure 2. Shoreline stabilization (2023). Photo credit: Helping Nature Heal.
Figure 2. Shoreline stabilization (2023). Photo credit: Helping Nature Heal.
Figure 3. Living shoreline construction, Prince Edward Island (PEI) (2022).
Photo credit: Helping Nature Heal.
Figure 3. Living shoreline construction, Prince Edward Island (PEI) (2022).
Photo credit: Helping Nature Heal.

The formula has been developed through rigorous scientific research and extensive testing. The research and innovation sector of Lambton College, Ontario, Canada, conducted a study on the tensile strength of HNH plant recipes combined with Abundance. The study concluded that “overall better results were obtained” from the use of Abundance. In particular, it was found that by month three, yellow willow plants treated with Abundance and an additional biomass layer experienced overall growth by 384.4%, compared to plants with no treatment experiencing only 16.7% growth. This significant increase underscores the impact of Abundance in promoting plant growth and stability, which is crucial for erosion control projects.

In addition to tensile strength studies, rigorous rainfall tests were conducted to further validate the effectiveness in erosion control. Three rainfall tests were conducted, with each lasting 15 minutes and conducted biweekly. The rainfall intensity was set at 100 mm/h (4 inches/hour), based on rainfall intensity-duration-frequency (IDF) curve data specific to the Sarnia, Ontario region in which the tests were conducted. The tests were performed on a slope set at 45 degrees to simulate challenging real-world conditions. Water runoff was measured, and soil runoff was collected, dried and weighed. These tests demonstrated that Abundance significantly reduced soil erosion and water runoff to 1% to 2% of the runoff measured without the use of bio-stimulant.

Reference

  1. Natural Resources Canada, Geological Survey of Canada — Atlantic. 2007. Understanding Nova Scotia’s Coastlines, p. 2.

About the Expert

  • Emillie Rose is the project manager at Helping Nature Heal in Bridgewater, Nova Scotia, Canada. She has an advanced diploma in fish and wildlife technology and is certified at Level 2 by Green Shores.