Options for Managing Coastal Erosion - Ecology Action · Coastal Erosion Presentation by: Ashley...

Options for Managing Coastal Erosion

Presentation by: Ashley Sprague

Shoreline stabilization methods • Armouring - Boulders/rockwalls most common method of erosion control in Nova Scotia

Concerns: - Accelerate erosion - Impact coastal processes - Cut off sediment supply - Access

Soft approaches • Fewer people using this approach • Range of native, salt tolerant species

Benefits: - Allows coast to function naturally - Habitat, water quality benefits Concerns: - High energy systems

Before you build Consider a vegetated setback

Living shorelines: An alternative approach Aim to optimize natural functions of the shoreline, while

reducing erosion risk

Upland area + intertidal zone + shallow water habitat = combined protection benefits

Integrated Coastal Management Natural shorelines are dynamic, interconnected

and provide many functions

Any action has the potential to adversely affect ecosystem services onsite and on larger scale

All elements of the shoreline should be considered simultaneously when making a decision

How do we decide?

Decision tree

Different sites require

different solutions

Factors considered:

-Level of bank erosion, bank height

-Presence of vegetation, marsh, beach

-Wave energy/exposure

-Water depth

Decision Tree Principles 1) Shorelines should be left in their natural condition

unless erosion has the potential to result in significant loss of property

2) Preserve and enhance natural shoreline elements where possible; and

3) Where impacts are unavoidable, locate erosion control treatments where they will have the least overall impact to ecosystem function

Fetch Distance across open water over which wind blows

and waves are generated

Fetch and water depth influence wave height and energy

http://ccrm.vims.edu

Banks

Level of erosion? (low or high)

Forested shoreline?

Bank height

- < 30 feet- Maintain vegetation and prevent large tree falls

- > 30 feet - Grade bank and use good upland management practices to prevent further erosion

http://ccrm.vims.edu

Bank grading

Before After

- Reduce the steepness of a slope (allow for wave run-up and improve vegetation growing conditions)

http://ccrm.vims.edu

Presence of a Marsh? Roots and grass stems provide erosion protection

Wider marshes = more wave reduction and protection

< 15 ft - encourage growth

> 15 ft - maintain marsh

Can’t force it

http://ccrm.vims.edu

Marsh Restoration

Before After

http://ccrm.vims.edu

Marsh Expansion A low fetch (< ½ mile) can provide ideal wave

conditions for marsh expansion

Fill may be needed

May require fibre log until roots from the plants are fully established

http://ccrm.vims.edu

Marsh Sill Higher fetch areas

Low-profile stone structure, allows marsh formation /restoration

placement depends on bank height, water depth and bottom type

http://ccrm.vims.edu

Beaches - Nourishment

http://ccrm.vims.edu

Beaches - Breakwaters

An off-shore structure to deflect force of incoming waves and contain sand beach

May be needed in actively eroding areas

http://ccrm.vims.edu

Living Shorelines in Nova Scotia EAC Future project

Property assessments with expert team

Identify and implement alternative methods

Monitor resiliency

Overland erosion More high intensity rainfall events

Increased area of impervious surfaces

High volume and rate of runoff

Can lead to erosion issues

Stormwater Management Approach to reducing runoff volume,

rate and pollutant load

Best Management Practices aim to

work with natural systems to promote infiltration, evaporation and water capture/reuse

‘Slow it, spread it, sink it”

Bioretention area

Individual Property Level Reduce impervious surfaces

Encourage water infiltration, capture and reuse

Opportunities: driveways, rooftops, lawns, plant trees

Costco.ca http://bit.ly/yP1aSN

Rain barrel Rain garden

Neighbourhood Opportunities: parking lots, streets, buildings

Vegetated islands Bioswale

Take home messages

There are options for shoreline stabilization – all will have impacts

Allow coast to do the work:

- Maintain existing vegetation

- Consider options before attempting shoreline hardening

Working with neighbours will benefit everyone

Blog – www.stormwatercentral.ca

Resources

Decision Tree Manual:

http://ccrm.vims.edu/decisiontree/decisiontree_manual.pdf

Contact: Ashley Sprague, Restoration Coordinator

Email: coastaloutreach@ecologyaction.ca

Phone: 902-442-5046