Coastal Erosion

CoastErosion

Increasing sea levels and storms will increase and intensify the rates of coastal erosion.

CoastUCSB

University of California, Santa Barbara before and after a strong El Nino storm. 1975 and 1983.

Coastal erosion is a natural process along the world’s coastlines that occurs through the actions of currents and waves and results in the loss of sediment in some places and accretion in others. Erosion rates tend to be higher in areas where soft substrates (e.g. sandstone or mudstone) are the dominant geological type rather than hard substrates such as basalt or granite. Despite the differences in erosion potential along the world’s coastlines, there has been a dramatic increase in coastal erosion over the last two decades1 and this is expected to continue as sea level rises2 and storm frequency and severity increase. Rather than occurring over the same time scale with sea level rise, erosion of beaches and coastal cliffs is expected to occur in large bursts during storm events as a result of increased wave height and storm intensity. Because of these large events, scientific models predict that shoreline erosion may outpace sea level rise by 50 to 200 fold3. For example, in 1938 Sakonnet Point, the most seaward point in the state of Rhode Island boasted large sand dunes that stood some 4.6 meters (~15 feet) tall. Today, those dunes are nearly completely submerged during high tide as a result of the combined impact of major storm damage and increased erosional forces. While sea level rose only .4 meters during this time period in this – the 4.6 meter dunes have all but disappeared at high tide.4 This example highlights the potential for erosional forces such as major storm events to outpace the rate of sea level rise. Erosion will have significant effects on coastal habitats, which can lead to social and economic impacts on coastal communities. With the reduction of coastal habitats and the ecological services they provide, coastal communities will experience more frequent and destructive flooding, compromised water supplies and smaller or fewer beaches.5

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