CHANGE IN THE ACTIVE VOLUME OF SEDIMENT ON DEVELOPED AND UNDEVELOPED BEACHES, SOUTHERN MAINE

Maine's sand beaches are one of the state's primary tourist attractions, but these natural resources are declining in quality and quantity due to encroachment by overdevelopment and rising sea level. Funding from the Maine Sea Grant program has enabled trained volunteers to make topographic measurements of ten important barrier systems in southern Maine, since July 1999. These beaches are significantly different with respect to physiography, incident wave energy and direction, available sediment supply, tendency to erode or accrete, and level of development. The volunteers use the Emery Method of beach profiling to make monthly measurements that document changes occurring to the sweep zone, or active volume of sediment, on each beach.

Results from a year of topographic profiling show that the active volume of sand is generally greater on undeveloped beaches than on developed beaches. The change in the volume of sediment from month to month does not show significant seasonal variability. A large decrease in sediment from the summer to winter months, and then an increase as summer approached, was expected. However, undeveloped beaches do demonstrate a large sweep zone during the winter months. In addition, there appears to be only a weak linear relationship between the transect length and the volume of active sediment when the beaches are divided into two groups based on their level of development. This relationship does not exist when all beaches are compared to one another.

Additional field work, including Ground Penetrating Radar surveys and moored wave and current meters offshore, will aid in determining the reasons for the monthly changes. The overall goal of the project is to determine how individual beaches respond to a variety of meteorological changes depending on their level of development and the volume of sand contained in, or available to each beach.