Coast And Society Final

Tectonically-Uplifted Coasts

Beaches and platforms raised faster than postglacial sea level rise

Isostatically-Uplifted Coasts are what? Ex?

British Isles Relative sea level fall in the north, rise in the south during last 10,000 yr

Hurricane Isabel was what number Cat and what year did it happen ?

Cat 2 hurricane, and in 2003

3000 yrs ago when barriers began to grow between valleys what did that cause?

Caused valley openings to narrow, decreased ocean-estuary dynamics, Marshes/Delta/Creeks formed.

If Ice sheets melt these things could happen again.

-Rise in sea level -10's of miles of west of present shoreline was the Suffolk Shoreline -East of the Suffolk Shoreline was under 20-25 ft. of water. - All coastal elements were displaced west

Inaction is?

Doing nothing to the coast

NC coastal system is the second largest..

Estuarine and wetland system in the US.

Goal of coastal management:

Facilitate human use of the coastal zone, but minimize the impact of such human use and protect human interest at the coast from natural and human-related processes.

Isostatically-Uplifted Coasts are what? Example?

Fjords Deep glacial erosion followed by isostatic rebound and eustatic rise

Eustatic Seal Level Changes includes:

Glacial Eustasy, Tectonic Eustasy, Sedimentation, Steric Effects, & Dynamic Eustasy

Fresh water is less dense that salt this is because of what effect.

Halosteric Effect

Ex. of Coastal Management - Florida Keys and Everglades

Intense tourism and development. Eutrophication of Florida Bay. Loss of sea grass and mangroves. Damage to coral reef ecosystems.

Coastal Protection and Zoning in England?

Inter-agency SCOPAC (Standing Conf. on Probs. Assoc. with the Coast). • Heritage Coasts.

Paleo Roanoke River reached continental shelf at..

Last Glacial Maximum -hence it was the first estuary to develop with RSLR 12,000 years ago.

Southern Pamlico Sounds underwent rapid environmental change associated with the ..

MCA 950-1250AD Large-scale barrier collapse from storminess between Buxton and Ocracoke (took 600yrs for them to build back)

Isostatically-Uplifted Coasts are what? And an example is?

Maine Glacial retreat followed by marine transgression, then regression

Reasons for coastal migration:

1. Caused by general population increase 2. Rural to urban migration 3. Migration to favorable climates and retirement destinations

5 things will likely happen in the next 100-300 yrs depending on the rates and magnitudes of climate change and RSLR

1. Flood lowlands by RSLR 2. Storm-driven erosion 3. Ecosystem evolution to changing environmental conditions 4. Upslope and landward migration of wetland ecosystem. 5.Regional land subsidence

There are 5 generic strategies for coastal defense:

1. Inaction 2.Managed retreat or realignment 3.Hold the line 4. Move seawards 5. Limited Intervention

As RSL rose following the LGM, the continental shelf flooded and sediments accumulated and preserved in two general locations...

1. shore-perpendicular stream valleys 2. shore-parallel beaches and estuaries (in front of uplands)

The Little Ice Age were between what years

1350-1850

Southern Modern Coastal System

145 to 2.6 Ma Underlain by older rocks Myrtle beach to Cape Fear (Carolina Platform High) Rocks were once exposed at surface truncated by shorelines Less accommodation space so less quaternary sediments 0-35 ft

The coastal zone occupies less than..

15% of the earth's land surface.

North Carolina has had a ban on permanent coastal structures since .

1985

By 2025, more people will live in the coastal zone than were alive in ...

1990.

Hatteras Flats

2-8 miles wide 2-10 below mean sea level broad shallow shoal system Some semi-permanent intertidal islands very productive biological habitat

Northern Modern Coastal System

2.6 ma Cape Lookout to Virginia Slowly Subsiding Albermarle Embayment Mostly Quaternary-sediment fill 50-250 ft. thick

Pop. of 865,000 resident in how many coastal counties.

20 coastal counties

50 million km3 of ice has melted since ...

20,000 years ago raising global sea level by 120-140m

Estimated that 3.1 billion people live within..

200 km of the coast

As Antarctic and Greenland melt RSL will rise ..

2010 projections 39-55 inches by 2100....~1/6th of Greenland Ice Sheet in 90yrs

How many US Military Bases on the NC coast

3

Because of the LIA how many major inlets are left and when did most inlets close.

3 major inlets left, most inlets closed in the 1800's

The present barrier system is said to have mostly developed in the last ..

3,000 years

Hurricane Isabel's Strom surge was how heigh, and what was the wind speed?

6-8 ft storm surge, and 100 mph winds.

Most large cities are in coastal locations .. what percentage has over 2 million people.

62% of cities over 2 million Major infrastructure zones for import/export, industry, finance.

How many drainage basins does the NC coastal system have?

8 major basins

The Pamlico Sound region flooding began

9,000 years ago, formed series of of narrow estuaries.

A big resource of coastal forestry is..

Mangroves

If Isabel had hit as a Cat 4/5 would we still have barrier islands?

Maps show possible barrier collapse due to either or combo of : -sea level rise -# and magnitude of storms -one or more direct hurricane landfall

How many inlets does the NC coastal system have?

More than 20 inlets

Hatteras flooded to form..

Pamlico Sound

Coastal Management issues include:

Pop. growth, Resource Exploitation, Ports & infrastructure, & Tourism/Recreation

Back-filled barriers are less susceptible to..

RSLR (relative sea level rise)

What is already evident from eroding and receding shorelines, narrowing islands near collapse.

Rising sea level from Antarctic and Greenland's ice melting.

Generally what kind of barrier island will collapse first?

Sand poor barriers

Short-term RSL may turn the barriers into..

Sandy Shoals

Overwash is NOT possible where...

Shoreline is bulit-up by manmade structures

Overwash is possible at..

Simple barriers and builds elevation and width

The Little Ice Age brought..

Storminess

One industry that has the potential to be compatible with coastal sustainability is ?

Tourism and Recreation

Coastal Protection Globally

UNESCO World Heritage Sites. Great Barrier Reef Marine Park.

Relative Sea Level Change

a local change in the position of the coast relative to the land. Causes include:

Highway 70 was built across...

a salt marsh with sediment fill.

Limited intervention..

accommodation, by which adjustments are made to be able to cope with inundation, raising coastal land and buildings vertically

Eustatic Sea Level Change

an absolute (global) change in the height of the ocean surface

How many miles of barrier island does the NC coast have?

approx. 325 Miles

A few years ago, Figure 8 Island petitioned for an exemption to the ban in order to build an "experimental" terminal groin at the north end of the island to protect ..

approximately 20 homes that are currently threatened by beach erosion.

Fishing lines, hooks, anchors and boat traffic threaten ..

aquatic vegetation, marine mammals and reefs.

Generally these complex systems were the spine of the..

barrier system with simpler barriers coming and going

3000 yrs ago, the barriers looked pretty similar to today but ..

began to grow in between valleys

Both sides of Hwy 70 is...

brackish and at sea level . 1 m rise should make it a wetland again.

Tectonic Eustasy

change in the size and shape of ocean basins.

Dynamic Eustasy

changes in water surface elevation due to geoidal anomalies, tides, storms, currents.

Beringia

connected Asia to Alaska; pathway for the first Americans

Sunda and Sahul

connections between Maylasia, Indonesia, Australia, Tasmania

Increase in ship size results in need for :

deeper wider shipping channels and larger ports.

Oil and gas reserves are (unsustainable), generally developed on..

deltas

5000 yrs ago, small barrier island begin to..

develop on the margins of the interstream-divide headlands (seaward of the modern system)

Warmer oceans may also contain more ..

dissolved elements and biological organisms, adding to the volume.

7500 yrs ago RSL flooded the deeper valleys near the present shore resulting in ..

drowned river estuaries which began to fill with mud.

Advancing and Retreating Coastlines include...

emergence, progradation, submergence, retrogradation

At LGM many narrow Coastal Plain streams..

eroded into the underlying bedrock up to 35 ft. -btwn streams higher elevation formed uplands

Geomorphic Processes

erosion/deposition processes that change the relative position of the coastline and also cause isostatic adjustments.

In some places the abundance of sand resulted in ..

fields. Ex. Kitty Hawk

Sedimentation

filling ocean basins with sediment eroded from land.

Measurements based on age and bathymetric depth of coral reefs in "far-field" areas not affected by ..

glacial isostasy

Rising sea level, increase in tropical storm intensity and storm surge is predicted with ..

global warming.

Thermal expansion accounts for about..

half of the current sea level rise. (Glaciers account for most of the rest)

Modification of the coastline includes:

harbor dredging, jetties and breakwaters, sea walls

More than 50% of global population lives ..

in the coastal zone.

Overwash is?

is the flow of water and sediment over the crest of the beach that does not directly return to the water body

Glacial Eustasy

loss/addition of ocean water by glacier growth/melt.

Human modifications of coastal systems reduces the ..

natural ability of the coast to recover.

Post-Bonnie (cat 2, 1998) washover sediments deposited by ..

overwash

The decision to choose a strategy is site-specific, depending on ..

patterns of relative sea-level change, geomorphological setting, sediment availability and erosion, as well a series of social, economic and political factors.

Destabilization of dunes and bluffs from foot and vehicle traffic disturbs..

plants and animals - then erosion/instability and degradation

coastal sustainability

preservation for future generations

Boat traffic leads to ..

sedimentation, pollution, eutrophication.

Longer-term RSL will cause ..

segments to collapse into the deeper Pamlico Sound

Ocean water density is controlled by:

temp. and salinity

Former sea levels can be correlated with ..

the ages of uplifted terraces and the tectonic uplift rate of the region.

Steric Effects

thermal expansion or contraction of ocean water

Move seawards..

this happens by constructing new defenses seaward the original ones

Increased population and property in the coastal zone leads ..

to greater potential for coastal damages.

Isostatic Processes

vertical adjustments of the crust due to changes in overlying mass (glacial isostasy: continents depressed by ice then rebounding; hydro-isostasy: ocean weight on the continental shelf).

Tectonic Processes

vertical motions of the land due to subduction, volcanism, folding/faulting at plate boundaries.

Density decreases as..

water warms and expands above 40. C (thermometric effect)

Hold the line, shoreline protection...

whereby seawalls are constructed around the coastlines

Managed retreat or realignment..

which plans for retreat and adopts engineering solutions that recognize natural processes of adjustment, and identifies a new line of defense and where to construct new defenses

The Future of sea level is? What is sea level rise mostly due to ?

• Best estimates suggest 20- 70 cm rise by 2100. • Mostly due to glacial eustasy and steric effects.

How fast is sea level rising?

• Current rates of sea-level rise are about 2-5 mm/year in tectonically stable areas.

Coast Protection in USA

• National Seashores/Lakeshores. • State agencies (NC Division of Coastal Resources). • Non-government (SeaGrant, Coastal Federation, Coastkeepers).

Eustatic sea level through geologic time:

• Sea level variations of ± 200 meters, reflecting global temperature, tectonics and glacial eustasy. • Cenozoic cooling and eustatic sea level fall, ending with rapid Quaternary ice age fluctuations. • Mesozoic warmth (high stand) due to rapid sea floor spreading, Pangaea breakup.

In the 20th Century the following things happened:

• Sea-level rose by 10-20 cm in most places. • Rate depends on local tectonic & isostatic factors.

Main sources are of management ex's:

• marine (offshore boat dumping) • fluvial (rivers entering coast) • beach (local tourist use)