Influence of Seawalls on Subaerial Beach Volumes with Receding Shorelines.
OLD DOMINION UNIV NORFOLK VA
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The results summarized herein are based on subaerial beach profiles taken on the Atlantic Ocean at Sandbridge, VA, which has experienced an average historic erosion rate of about 2 myear for more than 120 years before seawall construction began in 1980. The purpose of this ongoing study is to determine, from statistically defendable data, whether or not the 15 different walled sections increase the existing erosional trend at adjacent, nonwalled beaches. Fifteen years of survey data are employed with eight to nine years of variable data taken before wall construction peaked in 1989. The main focus of these results is on 5 full wave years of monthly and poststorm survey data taken at 28 locations 16 walled locations 62 percent, totaling 4,470 m and 12 nonwalled locations 38 percent, totaling 2,950 m since October 1990. Three time scales historic, seasonal, storms and three analysis methods were used to address three questions concerning the effects of seawalls on adjacent beaches. It has been determined that volume erosion rates are not higher in front of seawalls. However, seasonal variability of sand volume in front of walls is greater than at nonwalled locations. Walled beaches were found to recover about the same time as nonwalled beaches for both seasonal transitions winter to summer and following erosional storm events.
- Physical and Dynamic Oceanography