Coastal erosion is the wearing away of land or the removal of beach or dune sediments by wave action, tidal currents, wave currents. Costal erosion is.

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Presentation transcript:

Coastal erosion is the wearing away of land or the removal of beach or dune sediments by wave action, tidal currents, wave currents. Costal erosion is a very important problem for individuals and property. Though mostly gradual and relatively unnoticeable over a year or two the rising sea level with a lot of storms or hurricanes can cause a few feet to hundreds of feet of this shoreline being stripped away. Erosion may take the long-term losses of sediment and rocks or temporary of coastal sediments. erosion in one location may result in a larger beach nearby, as the sand is "moved" from one stretch of beach to another.

Erosion On the Outer Banks Softer rocky areas become eroded much faster than harder ones On North Carolina coastal erosion typically is more of a danger to where humans live like coastal towns and oceanfront structures than it does to nature itself and human interference can also increase coastal erosion. North Carolina's beaches erode more in the stormy fall and winter months than in the calm summer months The waves erode some of the sediment and take it somewhere in the ocean but the storms like hurricanes are the ones to take most of it /

Beach Nourishments: piles on new sand to a beach making it wider and higher above sea level for a long time groins were the preferred approach to controlling beach erosion in most coastal areas. Groins, usually constructed in sets called groin fields, extend like fingers away from the shore. Jetties usually extend far enough from the shoreline to completely block the movement of sand

Structures To Reduce Erosion Groin fields are designed to trap and to keep sand nourishing the beach compartments between them. Jetties are usually built to reduce shoaling in navigation channels and function like groins stopping the movement of sand and other material where it can be swept away with the waves. Most of these techniques that we use can work for a long period of time but like most structures built to block erosion nothing is guaranteed or permanent. osion/

In all the years that we have been using these structures they have worked no matter how strong the structure is there are always examples of how the power of the sea and waves can overcome human efforts to protect the coast. smaller structures that are built to protect a small amount of property like groins, bulkheads and jetties have been blamed for the rise in erosion rates down the coast. osion/

Advantages and Disadvantages of Structures These structures can cause uncontrolled and undesired development or erosion in other areas Seawalls are also temporarily successful at protecting buildings or roads but most seawalls fail sooner than they expect Seawalls influence the beach in front of them in various ways These waves often cause the sand beach in front of a seawall to erode twice as fast as an adjacent beach without a seawall.

The replenishment of a beach sand either naturally or artificially Beach nourishment is the supply of sand to the shore to increase the value and/or to secure the beach against shore erosion by feeding sand on the beach Beach nourishment. The placement of sand, from other sand sources, on a beach or dune nourisment/

Nourishment restores and widens the beach Structures behind beach are protected as long as the added sand remains. This is a big advantage when compared with structures like seawalls or groins. Seawalls may protect structures behind the beach but they almost always cause the beach in front of the wall to become narrower. If erosion breaches the seawall, then debris from the wall will be left on the beach and in the surf. Since beach nourishment only puts sand on the beach shmentinfo.html

Beach nourishment sand often (in fact, usually) erodes faster than the natural sand on the beach. A good rule of thumb is that nourished beaches erode two or three times faster than natural beaches. Erosion rates can differ widely, however. The biggest factor for the lifetime of a nourished beach is the number of storms that affect the beach. Storms are unpredictable, so nourished beach lifetimes are unpredictable too. The amount of sand added per yard of beach length and the sand placement design determine the new beach width. Wider nourished beaches last longer. Beach nourishment is expensive, and must be repeated periodically. Except on very small beaches, the minimum expenditure is usually $1 - $2 million dollars; larger, longer- lasting projects often cost much more (e.g., $100 million - 1 billion).

Just a couple of weeks away from the end of the biggest beach nourishment project on the Outer Banks. The past 5 and ½ months has brought a new beach to Nags Head and South Nags Head.