The Influence of Seawalls on Beach Responses to Storms, Seasonal Transitions and Long-Term Erosion

Date of Award

Fall 1994

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil & Environmental Engineering

Program/Concentration

Civil Engineering

Committee Director

David R. Basco

Committee Member

A. Osman Akan

Committee Member

George F. Oertel

Call Number for Print

Special Collections LD4331.E54H29

Abstract

It has been argued that seawalls have a detrimental effect on the adjacent beaches. These effects may only be noticeable over a period of years or may be short-term effects associated with storms or with seasonal transitions of the beach. Many theories on beach and seawall interaction have been speculative and have lacked actual field or laboratory evidence for their basis.

This study uses four years of monthly and post-storm beach profile data to examine what influences the seawalls at Sandbridge, Virginia have on the adjacent beaches. Long-term effects of the seawalls are analyzed using fourteen years of profile data. Five parameters are defined to describe the beach profiles. Changes in the profiles parameters in time are quantified using three methods of analysis.

A larger subaerial volume seaward of the wall was removed during storms than seaward of an imaginary partition extending from a nearby wall for non-walled beaches. Beaches backed by seawalls recover from storms and winter seasons at the same time as non-walled beaches. The active seasonal seaward volume was larger for the wall profiles. The four year shoreline recession rate was statistically higher for the dune profiles. The volume seaward erosion rate was statistically higher for the dune profiles. The berm elevation recession rates were statistically equal for the dune and wall profiles. There is support for the hypothesis that the landward dune volume is eroding at a faster rate due to seawall construction on adjacent beaches.

Rights

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DOI

10.25777/51q2-6s86

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