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Introduction to North Carolina Project

Introduction:

Sea Level Rise is one of the more serious and certain consequences of climate change. The east coast of USA, with more than 100 years of shoreline position and tide data available, sea level rose varying between 20-40cm during the 20th century— variation due to ongoing glacial isostatic adjustment. For East Coast sandy beaches, Leatherman et al. (2000b) demonstrated that shoreline change rate is about 150 times that of sea level change rate. In North Carolina, outer coastal plain slopes average 1/2000 and are as gentle as 1/10,000, which means that in the absence of other factors, a SLR of 1cm could result in a retreat of 20 to 100m over the next century through inundation alone (Pilkey, 2004).

The major impacts of an increase in the rate of sea level rise in North Carolina are increased erosion, flooding and storm damage. SLR acts as an enabler of erosion because higher water level allows waves to act further up the beach profile and carry sediment seaward. There is substantial evidence that that the effect of storms on shoreline position is episodic on sandy beeches. (Zang, 2004).

Erosion:

Shoreline erosion has consumed approximately 125 km2 over the past 25 years, as much as 60% of wetlands in northeastern North Carolina (Riggs and Ames, 2003). The 93 miles of shoreline from Cape Hatteras to the Virginia line average 4.7 feet of erosion per year. Annual rates for selected segments of developed beachfront property exceed 10 feet per year (Mineral Management Service). It has been found that open ocean sandy beaches on the U.S. east coast not affected by inlets or engineering modifications erode at a rate 150 times the rate of sea level rise (Douglas, 2001)

Flooding

Rising sea levels flood beaches and bluffs, forcing estuarine waters up river valleys and adjacent land slopes. Rates of shoreline recession vary dramatically alongshore and are a function of shoreline type, geometry and composition, geographic location, size and shape of the associated coastal water body, coastal vegetation, and water level, storm frequency and intensity (Riggs and Ames, 1993).

Storm Damage

The coast of North Carolina can expect to receive a tropical storm once every four years, while a tropical cyclone affects the state every 1.3 years (State Climate Office of North Carolina). Higher storm surges, even from relatively minor storms, can be expected from rising sea level and subsequent storm damage along coasts. In addition, hurricane intensity is increasing, with a possible link to a warming ocean.

Salt Water Intrusion

The majority of the NC coastal zone is within a few centimeters of current sea level because of low topographic slopes of less than five centimeters rise per one kilometer. Rising sea level would allow saltwater to infiltrate farther inland and upstream. Higher salinity affects surface and groundwater, impairing water supplies, ecosystems, and coastal farmland as well as harming aquatic plants and animals.

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