Coastal hazards
Rapid-onset hazards last a few minutes to several days and encompass significant cyclones accompanied by high-speed winds, waves, and surges or tsunamis created by submarine (undersea) earthquakes and landslides.
[1] Since early civilization, coastal areas have attracted human settlement due to their abundant marine resources, fertile agricultural land, and opportunities for trade and transport.
Over the years, human society has often failed to recognize the hazards associated with these dynamics,[3] leading to major disasters and societal disruption.
The devastation caused by Hurricane Katrina in the southern United States in 2005 and Cyclone Nargis in Myanmar in 2008 underscores the importance of timely and effective coastal hazard management.
There are many different types of environments along the coasts of the United States with very diverse features that affect, influence, and mold the near-shore processes that are involved.
Understanding these ecosystems and environments can further advance the mitigating techniques and policy-making efforts against natural and man-made coastal hazards in these vulnerable areas.
[6] Barrier island coastline Barrier islands are a landform system that consists of fairly narrow strips of sand running parallel to the mainland and play a significant role in mitigating storm surges and ocean swells as natural storm events occur.
The morphology of the various types and sizes of barrier islands depends on wave energy, tidal range, basement controls, and sea level trends.
The various sedimentary, metamorphic, and volcanic rock formations assembled along a tectonically disturbed environment, all with altering resistances running perpendicular, cause the ridged, extensive stretch of uplifted cliffs that form the peninsulas, lagoons, and valleys.
[8] Marginal-sea type coastline The southern banks of the United States border the Gulf of Mexico, intersecting numerous rivers, forming many inlets bays, and lagoons along its coast, consisting of vast areas of marsh and wetlands.
This region of landform is prone to natural disasters yet highly and continuously developed, with man-made structures used to address water flow and control.
[6] Coral reef coastline Coral reefs are located off the shores of southern Florida and Hawaii, consisting of rough and complex natural structures along the bottom of the ocean floor with extremely diverse ecosystems that absorb up to ninety percent of the energy dissipated from wind-generated waves.
This process is a significant buffer for the inner-lying coastlines, naturally protecting and minimizing the impact of storm surges and direct wave damage.
Because of the highly diverse ecosystems, these coral reefs not only provide shoreline protection but also deliver an abundance of services to fisheries and tourism, increasing their economic value.
Flash flooding is caused by massive amounts of rainfall during storms flowing down into an area over a short period of time.
Erosion can occur along shore currents due to tides, sea level rise and fall, and high winds.
Larger amounts of erosion cause the coastline to degrade at a faster rate and can destroy areas of habitation, leaving less land to develop or preserve.
Examples of pollution that affect the coastal regions include fertilizer runoff, oil spills, and dumping of hazardous materials into the oceans.
The overall construction of buildings and houses on the coastline can remove natural barriers which handle the fluctuation in water and sea level rise.
Whereas the natural dynamics that shape our coastlines have been relatively stable and predictable over the last centuries, much more rapid change is now expected in processes such as sea level rise, ocean temperature and acidity, tropical storm intensity, and precipitation/runoff patterns.
[17] The world's coastlines will respond to these changes in different ways and at different pace depending on their bio-geophysical characteristics, and as such, past coastal trends often cannot be directly projected into the future.
CZMA establishes the national policy for the development and implementation of regulatory programs for coastal land usage, which is supposed to be reflected in state legislation such as CAMA.
The goal of this legislation was to create a management system capable of preserving the coastal environment, ensure the preservation of land and water resources, balance the use of coastal resources, and establish guidelines and standards for conservation, economic development, tourism, transportation, and the protection of common law.
Some of the hazards include the movement of barrier islands, sea level rise, hurricanes, nor'easters, earthquakes, flooding, erosion, pollution and human development along the coast.
[23] The development of the land can strongly affect the sea,[24] for example, the engineering of structures versus non-structures and the effects of erosion along the shore.
Bulkheads are man-made structures that help protect the homes built along the coast and other bodies of water that actually induce erosion in the long run.
