Date of Award
Master of Science in Geology
John J. Fisher
The shoreline with its constantly changing patterns of erosion and accretion represents a unique problem in the area of coastal planning and development. The field collection of shoreline change data is expensive, time-consuming and presents a problem in extrapolating short-term changes into long-term trends. The use of aerial photography to make quantitative measurements is a low cost technique that provides detailed coverage of the shoreline and its transient features.
Photogrammetric areal measurements of Nantucket Island, Massachusetts were made using a Bausch and Lomb Zoom Transfer Scope for four sets of aerial photographs taken between 1938 and 1970. Sequential overlays of the shoreline were prepared and areal measurements taken for shoreline segments 305 m in length using a square grid counting technique. The accuracy of this photogrammetric techniques was found to average 2.4 percent in ground truth surveys. Long-term annual changes (32 years) reveal that the eastern shoreline of Nantucket from Great Point to Tom Nevers Head was eroding at the rate of 0.56 m/yr while the south shore from Tom Nevers Head to Smith Point had a net erosion rate of 2.11 m/yr. The north shore from Smith Point to the west jetty was eroding at a rate of only 0.1 m/yr in contrast to a net accretion rate of 0.72 m/yr measure for the north shoreline from the east jetty to Great Point. The islands of Tuckernuck and Muskegat were generally eroding over the entire 32 year study period with Tuckernuck losing a net 480,000 m2 (mostly on the south shore) and Muskegat losing 107,500 m2. Recent shoreline changes on Nantucket and the surrounding islands as revealed by 1974 and 1976 Landsat imagery indicated changes in the position of sand spits at the end of Smith Point and on Muskegat. Satellite imagery was not found to be useful in making quantitative measurements because of its limited resolution characteristics.
Material eroded from the shoreline that is not redeposited downdrift appears to be stored in a number of shoreface connected sandwaves or ridges along the south and east shoreline.
Goetz, Michael Joseph, "An Aerial Photogrammetric Survey of Long-Term Shoreline Changes, Nantucket Island, Massachusetts" (1978). Open Access Master's Theses. Paper 2051.