EROSION SCOUR AND GEOLOGIC EVOLUTION OF CROATAN SOUND, NORTHEASTERN NORTH CAROLINA

Scour is an active erosional process in North Carolina's coastal sounds. The erosional effects of scour occur at four time scales: 1) two are short-term responses to individual high-energy storm events and series of storm events that occur within a year (hours to 1 year) or over a few year period (1-10) years), and 2) two are long-term cumulative responses through decades (10-100 years) and centuries (100-1000 years) that lead to major evolutionary changes within the coastal system. The cumulative impact of multiple short-term storm events produce the long-term evolutionary changes over greater time periods. Short-term processes and rates of bottom scour have significant impacts on cost of design, construction, and maintenance of bridge foundations, while long-term processes become important considerations for new bridge structures with design lives of 75 years and more. This research used Croatan Sound, a known high-energy, erosional-scour environment, as a test case to evaluate the rates of change and timing of scour events during the past several hundred-year history of Croatan Sound. The goals were to: 1) develop an understanding of long-term processes of evolutionary change within the estuarine system and 2) hindcast historic rates of scour as an aid to predicting future potential scour for North Carolina's coastal sounds.