Overview:

    The interactions between the hydrosphere, atmosphere, lithosphere and people in the study of coastal erosion make this topic an ideal example of an Earth System Science study. When looking at an earth system, the interaction between people and their physical surroundings can become complicated. The issues associated with coastal erosion and land management include factors such as the environment, government, and individual needs. Reaching a balance between these factors is a big challenge.
 

Research Problem:

How are urbanization, societal change and technological advances increasing or decreasing the damage caused by coastal erosion and catastrophic storms?
 
 

Background:

    The beach-ocean system can be considered to be in a dynamic equilibrium.  Sand that is moved off-shore by winter storms, leaving steep narrow beaches and ocean sand bars, is returned to the shore by the gentle waves of summer, creating wide, gently sloping beaches without ocean sand bars. However, the reality is that an equilibrium situation does not exist. Beaches do not qualify as a closed system because sand is regularly being lost from the system.

    Coastal erosion occurs when wind, waves and long shore currents move sand from the shore and deposits it somewhere else. The sand can be moved to another beach, to the deeper ocean bottom, into an ocean trench or onto the land side of a dune. The removal of sand from the sand-sharing system results in permanent changes in beach shape and structure.

    Forces that are constantly changing beaches combine with forces such as rising sea level and human activity, to create several concerns regarding the shape and future of the shore line on the east coast.

    Issues such as erosion control, restoration of beaches and preparation for catastrophic events need to be dealt with by coastal communities. The response to the challenge varies from locality to locality, with local, state and federal governments each having a part in the final action plan that is implemented.

The natural factors that influence the coast are:

Other beach erosion factors:
Summary of Natural Factors Affecting Shoreline Change
 
FACTOR EFFECT TIME SCALE COMMENTS
Sediment supply (source and  sinks Accretion/Erosion Decades to Millennia Natural supply from inland or shoreface and inner shelf sources cna contribute to shoreline stability or accretion
Sea Level Rise Erosion Centuries to Millennia Relative sea level rise
Sea Level Change Erosion Months to years Causes poorly understood
Storm surge Erosion Hours to days Very critical to erosion magnitude
Large wave height Erosion Hours to months Individual storms or seasonal effects
Short wave period Erosion Hours to months Individual storms or seasonal effects
Waves of small steepness Accretion Hours to months Summer conditions
Alongshore currents Accretion, no change,  
or erosion		 Hours to millennia Discontinuities (updrift//downdrift) and nodal points
Rip currents Erosion Hours to months Narrow seaward-flowing, near-bottom currents may transport significant quantities of sediment during coastal storms.
Underflow Erosion Hours to days Seaward-flowing, near-bottom currents may transport significant quantities of sediment during coastal storms.
Inlet presence Net erosion;high  
instability		 Years to centuries Inlet-adjacent shorelines tend to be unstable because of fluctuations or migrations inlet position; net effect of inlets is erosional owing to sand storage in tidal shoals.
Overwash Erosional Hours to days High tides and waves cause sand transport over barrier beaches
Wind Erosional Hours to centuries Sand blown inland from beach
Subsidence, Compaction Erosion Years to millennia Natural or human-induced withdrawal of subsurface fluids
Subsidence, Tectonic Erosion/Accretion Instantaneous, centuries to millennia Earthquakes; Elevation or subsidence of plates
 
 [from Managing Coastal Erosion, W. Wood, Nat. Research Council 1990]
 
Human intervention alters these natural processes through the following actions:
Physical Diversity

    Coastal shorelines differ markedly in physical characterisitics and in vulnerablility to erosion.  Erosion rate over time at a given point along the shoreline depends on factors such as:

Further Investigations:

    Studies associated with coastal issues:

    Inquiry directions for investigation of erosion:  
Studies associated with other hazards:
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Coastal Hazard Case Study / Activities for Students / Further Investigations / Standards Connections
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