The erubayment protected by North Beach, which includes Pleasant Bay and 

 Chatham Harbor, covers 2996 hectares at mean high water (MHW). Tidal ranges 

 vary within the bay from 1.3 meters at Chatham Harbor entrance to 0.9 meter at 

 Little Pleasant Bay. The mean tidal range in the Atlantic Ocean opposite 

 Pleasant Bay is 2.0 meters, and 1.2 meters in Nantucket Sound (U.S. Army 

 Engineer Division, New England, 1968). 



The ocean front of Nauset Spit has eroded and migrated landward. Zeigler 

 (1960) compared elevation transects surveyed from 1957 to 1959 to those of 

 Marindin (1889) and concluded that the rate of erosion is 1.2 to 1.8 meters (4 

 to 6 feet) per year where Nauset Spit is being driven into the marshes behind 

 it. Overwash is the principal process transporting sediment across the 

 barrier where backed by headlands or extensive salt marshes. Inlets, through 

 the development of their extensive flood tidal deltas, have heen responsible 

 for the large expanse of salt marsh in Nauset Harbor and upper Pleasant Bay. 



Nauset Spit lias always been of interest to coastal scientists because of 

 its dynamic character. Mitchell (1873) and Marindin (1889) provide historical 

 analyses of the spit, based on field surveys. Nickerson (1<)31) summarized 

 their analyses and other historical accounts. More recent studies which en- 

 hance the knowledge and understanding of the barrier system include Ziegler, 

 et al. (1964), Goldsmith (1972), Gatto (1975). Giese (1978), McClennen 

 (1979), ami the U. S. Army Engineer Division, New England (1979). Pertinent 

 studies are discussed further in relationship to the results obtained from 

 this research. 



II. OVERWASH AND AEOLIAN TRANSPORT 



1. Introduction. 



Major studies of the overwash role in barrier beach dynamics have been 

 conducted during the past two decades. Howard (1939) and Wiiby, et al. (1939) 

 provided detailed accounts of the effects of the 1938 hurricane on the south 

 shore of the Long Island barriers, based solely on poststorm observations. 

 Hayes (1967) noted that overwash caused by hurricanes has played a major 

 role in the infilling of Laguna Madre behind Padre Island, Texas. Washover 

 deposits were subsequently reworked by the wind, which transported additional 

 sediment landward. Pierce (1969) adopted the sediaant budget approach to 

 estimate the volume of net sediment transport and define relative roles of 

 inlets, overwash, and aeolian processes in landward migration. He calculated 

 the relative proportions as follows: 70 percent inlets, 15 percent overwash, 

 and 15 percent aeolian transport. There have been many qualitative papers on 

 the role of overwash in barrier beach dynamics (e.g., Andrews, 1966; Kraft, 

 1971; Godfrey and Godfrey, 1974). 



The first researchers to collect field data during a major storm were 

 Fisher, Leatherman, and Perry (1974). They used a hand-held current meter to 

 measure the velocity of overwash surges at Assateague Island, Maryland. 

 Prestorm and poststorm elevation profiles documented the amount of deposition 

 and subsequent wind deflation of overwash sediments. Leatherman (1976) 

 continued these studies. Storm tide and barrier elevation were found to be 

 the most important parameters in determining the magnitude of overwash. It 

 was determined from field surveys that overwash deposition was nearly equaled 

 by aeolian deflation, resulting in minimal net change on the fan surface after 



27 



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