Coastal Processes 101 & The Regs

Greg Berman

(Woods Hole Sea Grant & Cape Cod Cooperative Extension)

March 26, 2019

Outline: • ~15 min talk

• Coastal Processes

• What is Erosion?

• Regulations

Coastal Processes 101 & The Regs

Glacial History

(Shaw et al., 2002)

25,000 yr ago 400’ below SL, ~1 mile thick By ~ 15,000 ice was gone.

11,000 years ago 6,000 years ago Present Day

Coastal

Processes

General Coastal Processes

Beach Profile Adjustments Large waves, which tend to occur in the winter in Massachusetts, cause the beach to temporarily change its profile.

Images adapted from Natural Hazard Considerations for Purchasing Coastal Real Estate in Hawaii - A Practical Guide of Common Questions and Answers, by University of Hawaii Sea Grant College Program, 2006.

Winter

Summer

Daily/Seasonal Variability

A beach undergoing net longterm retreat will maintain its natural width.

Beach loss eventually occurs in front of a seawall for a beach experiencing net longterm retreat.

Images adapted from Natural Hazard Considerations for Purchasing Coastal Real Estate in Hawaii - A Practical Guide of Common Questions and Answers, by University of Hawaii Sea Grant College Program, 2006.

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Seasonal VS Long Term Erosion

Barrier Beach

Town Beach

System migrates landward across the shelf and SL as rises.

Perpendicular to Shore

1st appeared as ridges (far out on continental shelf) flooded by SLR

Rising SL breaches the beach ridge and floods behind creating a bay.

Overwash: Storms push sand across the island and into the lagoon area beyond. Barrier `rolls over on itself.‘

Coastal Processes: Barrier Migration

Perpendicular to Shore

Coastal Processes: Barrier Migration

Perpendicular to Shore

Adapted from http://www.nasa.gov/vision/earth/lookingatearth/katrina_poststorm.html

Peggotty Beach 2016

Video by Peter Miles

General Coastal Processes

Sea level rise

has been

occurring for

thousands of

years. During

this time barrier

beaches have

migrated

landward

through natural

coastal

processes and

have avoided

“drowning in

place”.

Evidence of Coastal Processes

“Transgressive” = a beach migrating landward and upward, covering the water body or salt marsh that lies behind it.

General Coastal Processes

Longshore Sediment Transport

Longshore Sediment Transport

Longshore Sediment Transport

Google Earth Engine: Timelapse is a global, zoomable video that lets you see how the Earth has changed over the past 32 years. It is made from 33 cloud-free annual mosaics, one for each year from 1984 to 2016, which are made interactively explorable by Carnegie Mellon University CREATE Lab's Time Machine library.

What is Erosion ?

The Erosion Problem: Education Perspectives

It’s all sediment transport! What is Erosion???..... just more leaving than coming in

Erosion Accretion Dynamic Equilibrium

Parallel Transport…….Blocked LST

Downdrift

Direction ofLongshore Current

Coastal Structure

Direction ofLongshore Current

Erosion

Deposition

+5’/yr+8’/yr

+4’/yr+3’/yr

-2’/yr

-2’/yr

0’/yr

-1’/yr

Source: MORIS: CZM’s Online Mapping Tool

Perpendicular Transport…….Blocked input

1.3mi

Coastal Processes: Key Points

1. Erosion of glacial landforms is the MOST important source of sediment for dunes and beaches in Massachusetts.

2. Wind and waves then transport sediment.

3. Without erosion and then longshore re-deposition there would be no beaches.

Coastal Processes: Key Points

1. Erosion of glacial landforms is the MOST important source of sediment for dunes and beaches in Massachusetts.

2. Wind and waves then transport sediment.

3. Without erosion and then longshore re-deposition there would be no beaches.

Thanks for contributing sand to our coastal resource areasThanks for contributing sand to our coastal resource areas

Thanks for contributing sand to our coastal resource areas

Erosion Control Structures

Designed to extend the “usable life” of a property.

Towns: Engineered structures may require nourishment

310 CMR 10: “no new coastal engineering structure on a coastal beach/dune/bank to protect a structure built after 8/10/1978”

Scientists wrote letter in 1970’s... MA “needs” erosion.

General practice 1920s – 1950s.

The Erosion Problem: Regulatory / Legal Perspectives

1. Post 1978 house 2. Scarp 50-60’ from house 3. Poorly maintained fiber rolls 4. Several OOCs included “no CES”

Is it acting as a sediment source?...only needs to “play a role”. Local ConCom permitted a rock revetment (CES). Abutters/Stakeholders appealed to State DEP

The Erosion Problem: Regulatory / Legal Perspectives

“No…you don’t understand…my house is going to fall in!”

1. Mix of Pre and Post 1978 houses 2. Scarp 5-50’ from houses 3. Revegetation of coastal bank attempted 4. Several OOCs included “no CES” 5. Town owned conservation land 6. Beach had Wetlands Restriction Act 7. Erosion down drift

Is it acting as a sediment source?...only needs to “play a role”. Local ConCom denied project. Likely changes/appeal coming soon.

Natural Heritage and Endangered Species Program The Natural Heritage & Endangered Species Program (NHESP), part of the DFW, is

responsible for the conservation and protection of hundreds of species that are not

hunted, fished, trapped, or commercially harvested in the state. The Program's highest

priority is protecting the 176 species of vertebrate and invertebrate animals and 259

species of native plants that are officially listed as Endangered, Threatened or of Special

Concern in Massachusetts.

State: Potential Habitat = historic and currently acceptable habitat

Towns: Potential Habit = historic habitat

2009 2013 2014 2016

Coastal Processes 101 & The Regulations

Questions ?

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