Nature-based Solutions for the Shoreline

Rather than coastal armouring structures such as seawalls and riprap, which degrade over time, disrupt natural shoreline processes, deflect wave energy, and are vulnerable to sea level rise, nature-based solutions can be used to protect our shorelines and the communities along them.

Coastlines are naturally dynamic systems and this can be a good thing for adapting to climate change if we understand and respect the natural processes at play. By working with nature, we can increase our resiliency to the impacts of climate change while also supporting and protecting biodiversity and human well-being.

Compared to traditional hard-armouring (left), nature-based solutions (right) can offer better protection from storm surge and sea level rise while maintaining high value habitat. Illustration by Holly Sullivan.

Here, we share a number of considerations and nature-based strategies for protecting our shorelines and communities.

Protecting the Upland

Protecting healthy and functioning coastal ecosystems starts with attention to the areas above the high tide mark, or the ‘upland’. By managing what happens on the upland, shorelines can be protected from excessive run‑off, contaminants, and erosion that would otherwise contribute to shoreline degradation. Here are a few suggestions:

Retain trees and snags – Avoid clearing of trees and shrubs along the shoreline as these provide important functions, for example as a food source, for shading, and riparian zone stabilization.

Practice eco-friendly gardening – Remove invasive species and encourage native species, and avoid chemical pesticides and fertilizers.

Reduce and treat run‑off – Use strategies such as rain gardens, permeable pavers and rainwater capture systems to minimize run-off from your property which can help reduce surface erosion and prevent contaminants from flowing into the aquatic environment.

Protect the riparian zone – A healthy riparian zone is key to the health of the shoreline as it acts as a buffer between the upland and the foreshore. The first step it to protect what is there:  but if the backshore vegetation has been cleared in the past, try to replant it with native species. Below is a table of suitable species for our local coastal riparian zones you can source from a native plant nursery.

TreesShrubsGrass & Wild Flowers
ArbutusNootka rosebeach wild-rye grass
Douglas-firoceansprayred fescue
Sitka sprucered flowering currantentire-leaved gumweed
shore pinesnowberrylarge-leaved lupine
red aldermock-orangeseashore lupine
big-leaf maplesweet galebeach pea
Pacific willowsalalsilvery burweed
cascaraOregon-grapebeach strawberry
Hooker's willowthimbleberrysea-watch
Douglas maplesalmonberrycow-parsnip
Scouler's willowIndian-plumCooley's hedge-nettle
Pacific crab appleblack twinberrycommon yarrow
vine maplekinnickinnickwooly sunflower
western red cedarPacific ninebark
Table adapted from tables included in Your Marine Waterfront (pg 37-39) and Green Shores Credits and Ratings Guide for Homes (pg 130).

Plan for sea level rise

Sea levels are rising – how a given area will be impacted will depend on the region and a number of other factors such as erosion and deposition rates, and geological factors like uplift and plate tectonics. In British Columbia, sea level rise is projected to be greatest on the north coast, the Fraser Lowland and southern Vancouver Island. See this map which shows vulnerability to sea level rise and coastal flooding.

Sea level rise will increase tide levels and how far seawater reaches onto land, influence the duration and frequency of inundation, exacerbate coastal erosion, and even cause the loss of nearshore habitat. Coastal modifications can exacerbate these impacts. To adapt we will need to:

Avoid further development directly on shorelines – Protect and preserve the natural areas we still have. Preserving shorelines in their natural state helps ensure important habitats are available to support biodiverse ecosystems and our coastal food web.

Accommodate for sea level rise – Increase setbacks, move infrastructure back if possible, and build any new structures further back from the shore. There is often a required regulatory setback that is established by local government regulations and this may vary by area. A safe setback distance that accounts for local sea level rise should be calculated based on site conditions by a qualified professional, whom would also ensure regulatory conditions are met.

Remove existing seawalls, riprap or other modifications to the shoreline – These structures, which are built with the intention to protect coastal infrastructure, actually disrupt coastal processes and are not an effective long-term solution for adapting to sea level rise. A shoreline is most resilient when it can function as an intact ecosystem.  

Undertake Restoration and Implement Nature-based Solutions

Successful restoration that improves ecosystem function and protects shoreline infrastructure requires a complete understanding of the dynamics of the area of shoreline you are working on. Enlisting qualified professionals (coastal geomorphologists/engineers, landscape architects, environmental consultants and biologists) is a critical step and will help you confidently design and plan a solution that considers natural coastal processes, shoreline erosion risk, and the dynamics of the ecosystem as a whole. The Stewardship Centre for BC has compiled a list of Green Shores Approved Professionals  that have the skills and experience for such projects.

Depending on the site being restored some nature-based solutions that may be recommended include:

Recontour the beach profile Recontouring can create great habitat benefits and provide shoreline protection. The aim of recontouring is to alter the slope of a beach so that it has a gentle gradient that will naturally dissipate wave energy. The process involves large machinery removing sediment from some areas and adding it to others to create the desired effect. Depending on the dynamics of a site, it may require maintenance over time to preserve the slope profile.

Beach nourishment – Sediment that is lost through erosion and not replenished by natural coastal processes can be replaced through a process called beach nourishment. Coastal modifications, such as groynes, jetties and breakwaters, disrupt longshore drift, which is responsible for maintaining the sand on beaches. Without natural replenishment, beaches that were once sandy or gravelly, may be stripped to cobble stones or bedrock. Having the right types of sediments on beaches is vital for forage fish, which spawn along the high tide line. To ensure the best habitat outcome, consult with a shoreline professional with expertise in coastal processes and forage fish requirements. They may suggest a ‘forage fish’ sediment mix that is specially formulated to suit the needs of species like Pacific sand lance, Pacific herring and surf smelt.

Incorporate large woody debris – Drift wood logs and other large woody debris can be placed along upper beaches and backshore, typically beyond the reach of the waves, to stabilize the shoreline and provide micro‑habitat for vegetation and animals. Depending on where they are placed, the natural untreated logs that are brought in may need to be anchored, either by partial burial or placing between rocks, to ensure they will not float away on the next high tide. Ideally, the logs will include intact roots or branches and be Douglas fir or western red cedar as they are naturally rot resistant. Once in place, the logs can help reduce erosion and accrete additional sediment on which dune grass and other shoreline plants may establish, further stabilizing and building up the beach.

Stabilize the shoreline with vegetation – Planting the riparian zone will stabilize sediment and prevent erosion along the shoreline. Having intact vegetation along the shoreline will also increase biodiversity, support marine food web linkages, and create incredible wildlife viewing opportunities. Besides planting native plant seedlings, there is another common method of revegetation, known as live staking, which involves sustainably harvesting cuttings from specific native species near by (e.g. red alder, snowberry, and Scouler willow) and staking them into the sediment and for them to eventually re-grow and stabilize the bank. Here is a photo from a marine riparian restoration on Thetis Island by SeaChange Marine Conservation Society, led by Dave Polster.

Case Study: Weaverling Spit Restoration Projects

A great example where all of these methods were utilized is the Weaverling Spit Restoration Projects by Samish Nation and Coastal Geologic Services, in Samish Territory, Anacortes, Washington. The project involved multiple phases of restoration along the shoreline including a long-term plan for managed retreat on Tribal Lands to allow for landward habitat migration. Below you will see how the shoreline was re-graded and restored and the benefits that have been achieved.

Prior to the restoration (left) Fidalgo Bay Resort was vulnerable to storm surges and experienced flooding and infrastructure damage. After regrading the shoreline and supplementing sediment (right), the site is more protected.

Weaverling Spit was experiencing erosion and, with lawn extending to the shoreline, there was no habitat connectivity (left) prior to recontouring the beach and planting riparian vegetation (right). The site is now more resilient to storm events and provides valuable habitat again. Large woody debris has naturally recruited and brought with it additional habitat and shoreline stabilization benefits described above. The beach was nourished with a forage fish sediment mix and, incredibly, they found surf smelt spawning the very next day!

Considering a project involving some or all of the above strategies?

Check out these helpful resources for additional information:

Put together for the Washington Department of Fish and Wildlife and adapted by the Stewardship Centre for British Columbia, Your Marine Waterfront Canadian Edition provides ways to promote healthy shorelines while protecting waterfront properties. Included are guidelines for site assessments and design techniques to plan and restore your shoreline and other helpful resources for shoreline property owners.

The Washington State Aquatic Habitat Guidelines Program has created Marine Shoreline Design Guidelines as comprehensive guide of shoreline assessment and management techniques. This guide provides detailed methods for site assessments, implementation of the nature-based solutions outlined above, and considerations and techniques for removal of coastal armouring.

You can take your project a step further and enroll your project with Green Shores  and go through Green Shores® accreditation process. Find out more from the SCBC website (Green Shores for Homes and Green Shores for Shoreline Development) and this Green Shores for Homes Credits and Ratings Guide.

Photo credits: Kelly Loch, Maria Catanzaro, Weaverling Spit Restoration 'before' photos courtesy of Todd Woodard, Samish Nation Natural Resources, after photos by Maria Catanzaro

Plant a Rain Garden

A rain garden is a great example of a nature-based solution to reduce stormwater runoff from your property. Rain gardens are attractive landscaping features that are specially designed to treat runoff and allow water to infiltrate the soil and recharge ground water.

With a rain garden, runoff from roofs and other impermeable areas around the property are directed to a sunken area where water can pond and move through a mix of mulch and constructed organic soils planted with appropriate native species. Rain gardens allow natural bio-remediation processes of microorganisms, plants, and soils to take place, which prevents contaminants making it to stream and shore habitats.

The group 12,000 Rain Gardens in Puget Sound shares a wealth of knowledge on building rain gardens that is specifically relevant to the Pacific Northwest. See their comprehensive guide on building a rain garden, and watch their video demonstration linked below.

Additional Resources

Check out our partner Peninsula Streams Society's blog about three Rain Garden Demonstration Sites they have built at urban schools in the Capital Region. This project has built storm and drought resilience into local watersheds! Within the post are a number of helpful and informative links.

For professional assistance with designing and building a rain garden, search for landscape architect firms through the BC Society of Landscape Architects.

Photo credit: Maria Cantanzaro and Paul de Greeff

Permeable Paving

A potential source of pollution entering waterways comes from stormwater runoff from around our homes. In particular, a paved driveway, which may have car oil and road residues, delivers contaminated runoff to gutters and drains that directly connect with aquatic environments.

Fortunately, there are options, such as permeable pavers, gravel or grass grid systems, and specialty concrete mixes, that allow storm water to filter through to the soils below.

Using these alternatives has a number of environmental benefits, including lower pollutant loads entering water ways, reduced erosion and flooding from flashy storm runoff and increased groundwater recharge. Additionally, less radiant heat is retained by these alternative systems compared to traditional concrete. This will reduce heat pollution that contributes to urban heat island effect.

Depending on the type of solution selected, installation methods and costs will vary. Typically, pavers are placed on a level bed that allows infiltration and spaces between are back-filled with fine gravel. Detailed installation guides and summaries of different options can be found online (here too).

Learn more about the how cars can cause water pollution and ways to reduce the impact, here.

Photo credit: Toinane on Unsplash, Nicole Christiansen and Paul de Greeff

Composting

When organic materials, including kitchen scraps and garden waste are sent to landfills they break down anaerobically and produce the potent greenhouse gas methane.

By composting you avoid this and the finished product is great slow releasing fertilizer and soil improver for your garden. By following a few simple guidelines and having a place for your heap, you can easily get started with composting.

How to Compost

First, decide which method you would like to use - The simplest is to have a compost bin or a heap at the far end of the garden to fill and aerate on occasion, but you might want to learn about other methods, check out these fact sheets put together by the Compost Education Centre:

Get yourself set up - Bins can be purchased from gardening centres, home improvement stores or from community composting organizations like the Compost Education Centre in Victoria or the Vancouver Compost Demonstration Centre. You can also create a place for your heap using lumber and fencing material, or things you may already have on hand (check out this post for 35 ideas), or just have a free form pile.

When choosing your bin (or lack of one) you will want to consider the type of materials you plan to compost. For example, if it is just yard waste you plan to compost you don't necessarily need a solution that is pest proof, but you would want something pest proof if you do plan to include kitchen scraps.

Simple bins, like the one pictured on the left, are designed for new material to be added at the top by removing a pest resistant lid, and for finished compost to be harvested from a door in the bottom.

Making 'black gold' for your garden - As a general rule for producing healthy rich compost, alternate layers of 'brown' - or carbon rich materials - such as dry leaves, paper, straw, with layers of 'green' - or nitrogen rich materials - such as fresh grass clippings and kitchen scraps. You want the ratio of green to brown material to be about equal. Everything should be turned occasionally and kept moist to ensure proper conditions for the microbial breakdown process.

There are a few things that you should avoid putting in your heap so that it won't attract pests, create odour, spread weeds or result in a compost that would be unhealthy for including in a veggie garden. The table below shows what to compost, coded as as green or brown categories by text colour, and what not to compost.

Great for compostDo not compost
Fruit and vegetable scrapsMeat/bones
Tea bags and coffee groundsDairy products
Rinsed egg shellsBread or cooked food
Fallen LeavesWeeds that have gone to seed
Grass clippings (fresh/dry)Weeds that have rhizomes
General garden waste (fresh leaves/woody)Diseased plants
Shredded newspaper/cardboardCat and dog waste
Human or pet hair
Chicken, cow or horse manure
Untreated wood saw dust/chipped
Straw

Watch and learn - A introductory video about simple backyard composting made by City Farmer.

Alternative Solutions

If you don’t have the desire or space to compost on your property, you can:

Invest in a counter top compost device - If you are really short on space and time, there are now counter top compost devices such as Lomi, which accelerate the compost process through grinding and heating. These devices, which use electricity, can turn kitchen scraps into 'dirt' in a few hours.

Use your municipal composting – your green bin. Learn what can go in your green bin and see what happens to the contents of your green bin.

For More Information

Check out the Compost Education Centre in Victoria, their website contains all sorts of helpful educational fact sheets on different methods of composting and other tips for your garden. They also offer workshops.

Visit the Vancouver Compost Demonstration Centre and pick up a cheap backyard compost bin or worm composter

Photo credit: Eva Elijas from Pexels, Nicole Christiansen