Coastal Impacts: Beaches, Sand Spits, and BluffsCoastal Impacts: Beaches, Sand Spits, and Bluffs

Amber Moore

University of Washington School of Marine Affairs

12 February 2009

Amber Moore

University of Washington School of Marine Affairs

12 February 2009

Impacts on Beaches and Sand SpitsImpacts on Beaches and Sand Spits Puget Sound’s shoreline is estimated at

2411km (1477mi) in length SLR will cause the landward migration

of the shoreline Coastal development could be

threatened by increased vulnerability of coastal property

Puget Sound’s shoreline is estimated at 2411km (1477mi) in length

SLR will cause the landward migration of the shoreline

Coastal development could be threatened by increased vulnerability of coastal property

Impacts on Beaches and Sand SpitsImpacts on Beaches and Sand Spits Beaches protected

by sea walls, riprap, or revetments are likely to be less stable than unprotected shores

The beaches of Puget Sound act as critical habitat

Beaches protected by sea walls, riprap, or revetments are likely to be less stable than unprotected shores

The beaches of Puget Sound act as critical habitat

Bainbridge IslandBainbridge Island

Contains 85.2km (53.3mi) of shoreline 82% currently in

residential, recreational, commercial, or industrial use

48% is armored Uplifted beach terraces,

bays, and coves are most susceptible to inundation

Contains 85.2km (53.3mi) of shoreline 82% currently in

residential, recreational, commercial, or industrial use

48% is armored Uplifted beach terraces,

bays, and coves are most susceptible to inundation

Southwest WashingtonSouthwest Washington

Ocean Shores has been actively eroding

Shorelines are relatively well protected within the shallow bays Willapa Bay and

Grays Harbor

Ocean Shores has been actively eroding

Shorelines are relatively well protected within the shallow bays Willapa Bay and

Grays Harbor

Bluff Erosion in Puget SoundBluff Erosion in Puget Sound

Feeds sediment for beach formation but also threatens property and human lives

The steepening of bluff slopes increases the probability of bluff failure

Key factors are storms with large waves, especially when combined with high tides or elevated sea levels

Feeds sediment for beach formation but also threatens property and human lives

The steepening of bluff slopes increases the probability of bluff failure

Key factors are storms with large waves, especially when combined with high tides or elevated sea levels

Western Whidbey IslandWestern Whidbey Island

Erosion rates have been measured from 1cm to more than 61cm (2ft) per year

Whidbey Is. bluffs are frequently sites for residential development

Erosion rates have been measured from 1cm to more than 61cm (2ft) per year

Whidbey Is. bluffs are frequently sites for residential development

Western Whidbey IslandWestern Whidbey Island

Many homes built on Whidbey Island were placed on artificial fill at the base of landslide prone bluffs

Along a 1 mile stretch of road, as much as $32 million worth of property could be involved

Many homes built on Whidbey Island were placed on artificial fill at the base of landslide prone bluffs

Along a 1 mile stretch of road, as much as $32 million worth of property could be involved

Bainbridge IslandBainbridge Island

Bainbridge Island has 394km (246mi) of shoreline, 20% of which is classified as “unstable”

Bluff erosion rates average between 5.1cm (2in) and 15.2cm (6in) per year

Bainbridge Island has 394km (246mi) of shoreline, 20% of which is classified as “unstable”

Bluff erosion rates average between 5.1cm (2in) and 15.2cm (6in) per year

San Juan IslandsSan Juan Islands

Presently very little bluff erosion The islands are composed mainly of exposed

bedrock coast Unlikely that an increase in SLR will affect the bluff

erosion patterns

Presently very little bluff erosion The islands are composed mainly of exposed

bedrock coast Unlikely that an increase in SLR will affect the bluff

erosion patterns

Adaptation OptionsAdaptation Options

Accommodation Protection

Sea walls, dikes, raising docks

Retreat Moving or building on

higher ground & further from bluffs

Accommodation Protection

Sea walls, dikes, raising docks

Retreat Moving or building on

higher ground & further from bluffs

Research GapsResearch Gaps

Incorporate additional sites into a future study Applied and basic research into movement of

sediments and shifts in beach and bluff profiles

How auxiliary structures will be and are being threatened by beach and bluff erosion

Representation of more ports More research into the effects of increased

SSTs and ocean acidification on shellfish

Incorporate additional sites into a future study Applied and basic research into movement of

sediments and shifts in beach and bluff profiles

How auxiliary structures will be and are being threatened by beach and bluff erosion

Representation of more ports More research into the effects of increased

SSTs and ocean acidification on shellfish

ConclusionConclusion

Global Climate Change is happening Will impact humans and coastal ecosystems Effective adaptive actions can enhance the

resilience of vulnerable systems

Global Climate Change is happening Will impact humans and coastal ecosystems Effective adaptive actions can enhance the

resilience of vulnerable systems