patrickbdevaney/mia9 · Datasets at Hugging Face

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both in 2004. Frances made landfall along the Atlantic coast, and Ivan made landfall along the Gulf of Mexico coast on Florida’s
panhandle. (Photos: USGS)
II
5

WHAT IS PROBABLE:
Continued sea-level rise will exacerbate erosion. Rising sea level may shift the beach profile, and therefore the shoreline, landward (Bruun, 1962; Dean,
1991). Analysis of data from along the entire U.S.
Atlantic coast indicates that there is a correlation between the long-term erosion rates and sea-level rise
rates. Thus, it is expected that long-term erosion rates
will increase as sea level rises.
Barrier islands will continue to change, and sandstarved barriers will migrate landward (Sallenger et
al., 2009). Large storms may lead to a “change in
state,” causing island breaching. Hurricane landfalls
and increased sea level will exacerbate the erosion
impacts. Furthermore, human development may prevent some of the natural process of island migration
and may lead to increased vulnerability or catastrophic failure.
Coastal transportation infrastructure will be affected.
Recent hurricanes provide guidance regarding the
damage to infrastructure. Notably, recent large hurricanes have destroyed bridges that connect coastal
communities to each other and connect barrier island
communities to the mainland.
Rising sea level will increase the size of bays behind
barrier islands and therefore increase the tidal prism
(the amount of water flowing through tidal inlets) and
alter the beach–inlet interaction. Beach–inlet interactions and associated tidal inlet management efforts
are responsible for more than 80% of Florida’s beach
erosion problems (Dean, 1988).
II. Sea-Level Rise and Its Effects
on Florida’s Ocean
and Coastal Resources
Example: Damage to bridge and roadway, Gulf Shores, Alabama. Hurricane Ivan, 2004. (Photos: USGS)
II

6

WHAT IS POSSIBLE:
Increased overwash, breaching of coastal roads,
and dissection of barrier islands may occur. There
are threshold levels of interaction between coastal elevation, sea level, and storm-driven surges and
waves. When these thresholds are crossed, dramatic
changes in coastal topography can result. Glimpses
of this sort of response are available from recent
storms that have made landfall in Florida.
Low barrier islands may vanish, exposing marshes
and estuaries to open-coast conditions. A location
that illustrates the progressive disappearance of barrier islands is the Chandeleur Islands, off the coast of
Louisiana. Here, a locally high rate of sea-level rise
exists because a substantial amount of land is subsiding. This example can be used as a proxy for what
might occur elsewhere if rates of sea-level rise increase to very high rates (i.e., 10 millimeters [about
3
/8 inch] per year), which are suggested in some
studies.
The changes seen in Louisiana result from losing the
sediment source of the Mississippi River tributary that
abandoned this region; however, the situation provides a rare glimpse into how coasts can respond to
a high rate of sea-level rise.
II. Sea-Level Rise and Its Effects
on Florida’s Ocean
and Coastal Resources
Example: Low barrier island topography with a small breach
that is due to landfall of Hurricane Ivan, 2004. (Photo: USGS)
Example: Progressive land-loss of the Chandeleur Barrier
islands. The islands are increasingly dissected as the beach is
lost, breaching prevails, and marsh lands erode. (Photos: USGS)
II

7

II. Sea-Level Rise and Its Effects
on Florida’s Ocean
and Coastal Resources
EFFECT : Changes in Estuaries, Tidal Rivers, and Coastal Forests
Although Florida tide ranges are relatively small, tidal effects extend far inland because much of the state is
low, relative to sea level, and flat. Because sea level has been rising only slowly for a long time, tidal wetlands such as mangrove forests and salt marshes have been able to accumulate sediment at the same rate
as the rise in sea level and grow into expansive habitats for estuarine and marine life. However, these tidal
wetlands are very sensitive to the rate of sea-level rise and will disappear if sea-level rise exceeds their capacity to accumulate sediment. With rising sea levels, sandbars and shoals, estuarine beaches, salt flats,
and coastal forests will be altered. Predicted changes in rainfall will alter freshwater inflow from tidal rivers
and in turn will affect salinity regimes in estuaries. This is likely to alter the communities of aquatic plants and
animals as well as patterns of terrestrial animals that also depend on these waters. Major redistributions of
mainland and barrier island sediments may harm or benefit existing wetland, seagrass, or fish and wildlife
communities, but these processes cannot be forecast with existing models.
WHAT WE KNOW:
Inland habitats are being affected long before inundation by sea-level rise because of ground-water
intrusion and abrupt changes from higher storm
surge (Sternberg and Swart, 1987; Langevin et
al., 2005).
The interplay of tides (and so sea level), freshwater
flows, and channel geometry establishes the physical and chemical features of tidal rivers (McPherson and Hammett, 1990). Changes to coastal
geological processes caused by sea-level rise
have the potential to significantly affect the distribution, abundance, and productivity of tidal river
ecosystems (Rodriguez et al., 2010).
Tidal wetlands may be keeping pace with current
rates of sea-level change by accreting vertically,
migrating upslope, or both (Williams et al., 2009;
Raabe et al., 2004) if there is a source of sediment or space landward of current wetlands. The
rate of soil accretion is critical for tidal wetlands to
keep pace with sea-level rise (Morris, 2010).
Open estuarine waters, some brackish marshes,
and mangroves in south Florida are expanding

both in 2004. Frances made landfall along the Atlantic coast, and Ivan made landfall along the Gulf of Mexico coast on Florida’s

panhandle. (Photos: USGS)

II

5

WHAT IS PROBABLE:

Continued sea-level rise will exacerbate erosion. Rising sea level may shift the beach profile, and therefore the shoreline, landward (Bruun, 1962; Dean,

1991). Analysis of data from along the entire U.S.

Atlantic coast indicates that there is a correlation between the long-term erosion rates and sea-level rise

rates. Thus, it is expected that long-term erosion rates

will increase as sea level rises.

Barrier islands will continue to change, and sandstarved barriers will migrate landward (Sallenger et

al., 2009). Large storms may lead to a “change in

state,” causing island breaching. Hurricane landfalls

and increased sea level will exacerbate the erosion

impacts. Furthermore, human development may prevent some of the natural process of island migration

and may lead to increased vulnerability or catastrophic failure.

Coastal transportation infrastructure will be affected.

Recent hurricanes provide guidance regarding the

damage to infrastructure. Notably, recent large hurricanes have destroyed bridges that connect coastal

communities to each other and connect barrier island

communities to the mainland.

Rising sea level will increase the size of bays behind

barrier islands and therefore increase the tidal prism

(the amount of water flowing through tidal inlets) and

alter the beach–inlet interaction. Beach–inlet interactions and associated tidal inlet management efforts

are responsible for more than 80% of Florida’s beach

erosion problems (Dean, 1988).

II. Sea-Level Rise and Its Effects

on Florida’s Ocean

and Coastal Resources

Example: Damage to bridge and roadway, Gulf Shores, Alabama. Hurricane Ivan, 2004. (Photos: USGS)

II

6

WHAT IS POSSIBLE:

Increased overwash, breaching of coastal roads,

and dissection of barrier islands may occur. There

are threshold levels of interaction between coastal elevation, sea level, and storm-driven surges and

waves. When these thresholds are crossed, dramatic

changes in coastal topography can result. Glimpses

of this sort of response are available from recent

storms that have made landfall in Florida.

Low barrier islands may vanish, exposing marshes

and estuaries to open-coast conditions. A location

that illustrates the progressive disappearance of barrier islands is the Chandeleur Islands, off the coast of

Louisiana. Here, a locally high rate of sea-level rise

exists because a substantial amount of land is subsiding. This example can be used as a proxy for what

might occur elsewhere if rates of sea-level rise increase to very high rates (i.e., 10 millimeters [about

3

/8 inch] per year), which are suggested in some

studies.

The changes seen in Louisiana result from losing the

sediment source of the Mississippi River tributary that

abandoned this region; however, the situation provides a rare glimpse into how coasts can respond to

a high rate of sea-level rise.

II. Sea-Level Rise and Its Effects

on Florida’s Ocean

and Coastal Resources

Example: Low barrier island topography with a small breach

that is due to landfall of Hurricane Ivan, 2004. (Photo: USGS)

Example: Progressive land-loss of the Chandeleur Barrier

islands. The islands are increasingly dissected as the beach is

lost, breaching prevails, and marsh lands erode. (Photos: USGS)

II

7

II. Sea-Level Rise and Its Effects

on Florida’s Ocean

and Coastal Resources

EFFECT : Changes in Estuaries, Tidal Rivers, and Coastal Forests

Although Florida tide ranges are relatively small, tidal effects extend far inland because much of the state is

low, relative to sea level, and flat. Because sea level has been rising only slowly for a long time, tidal wetlands such as mangrove forests and salt marshes have been able to accumulate sediment at the same rate

as the rise in sea level and grow into expansive habitats for estuarine and marine life. However, these tidal

wetlands are very sensitive to the rate of sea-level rise and will disappear if sea-level rise exceeds their capacity to accumulate sediment. With rising sea levels, sandbars and shoals, estuarine beaches, salt flats,

and coastal forests will be altered. Predicted changes in rainfall will alter freshwater inflow from tidal rivers

and in turn will affect salinity regimes in estuaries. This is likely to alter the communities of aquatic plants and

animals as well as patterns of terrestrial animals that also depend on these waters. Major redistributions of

mainland and barrier island sediments may harm or benefit existing wetland, seagrass, or fish and wildlife

communities, but these processes cannot be forecast with existing models.

WHAT WE KNOW:

Inland habitats are being affected long before inundation by sea-level rise because of ground-water

intrusion and abrupt changes from higher storm

surge (Sternberg and Swart, 1987; Langevin et

al., 2005).

The interplay of tides (and so sea level), freshwater

flows, and channel geometry establishes the physical and chemical features of tidal rivers (McPherson and Hammett, 1990). Changes to coastal

geological processes caused by sea-level rise

have the potential to significantly affect the distribution, abundance, and productivity of tidal river

ecosystems (Rodriguez et al., 2010).

Tidal wetlands may be keeping pace with current

rates of sea-level change by accreting vertically,

migrating upslope, or both (Williams et al., 2009;

Raabe et al., 2004) if there is a source of sediment or space landward of current wetlands. The

rate of soil accretion is critical for tidal wetlands to

keep pace with sea-level rise (Morris, 2010).

Open estuarine waters, some brackish marshes,

and mangroves in south Florida are expanding