column was filled with painted sand. Using the automatic level,, the surface 

 elevation was recorded at the top of the painted sand column. After an 

 overwash, the top of each sand plug was relocated and the surface elevation 

 determined by surveying. The amount of erosion, as well as the depth of 

 poststorm sedimentation, can be determined from plug analysis (Fig. 14). 

 Plugs were reset for later use by returning the painted sand column to the 

 surface and resurveying the elevation of the top of the plug. 



(Initial elevation) 



( peststorm ) 



Plug of 

 Painted Sond 



Maximum Ospth of 

 PREOVERWASM Ovsrwosh Erosion POSTOVERWASH 



Figure 14. Sand plug method for determining maximum depth of erosion. 



c. Analysis of Data , large washovers were placed along Nauset Spit- 

 Eastham during the 6 and 7 February 1978 storm (Fig. 13). Approximately 

 three-quarters of the dunes ware eroded during the storm; 1200 meters of wash- 

 over breach resulted from storm erosion. One-quarter of the salt marsh adja- 

 cent to the dune line was buried by washovers. Sand was deposited up to 250 

 meters landward of the berm crest, burying the living salt tnar6h. The berm 

 crest • as displaced landward between 5 and 20 meters. The greatest shoreline 

 erosion occurred about 100 meters south of the Coast Guard Heach parking lot 

 where a long, shallow embayment developed during the storm (Fig. 10). 



Overwash occurred at all three research sites on Nauset Spit-Eastham 

 during the February 1978 storm. Bench marks and base lines were relocated 

 after the 6tcra so that exact measurements could be made. 



d) Site 1 Washovar . Site 1 was the only washover on Nauset Spit- 

 Eastham between T572 and 1976. In June 1977 an elevation transect was 

 established across the feature to document changes in elevation (Fig. 11). 

 This transect extended the length of the throat (0W to 65W), crossed a pair of 

 small dunes (65W to 9QW) , two sand roads (90W to IQOa) and the 1972 washover 

 fan (HOW to 115W), and finally terminated in the unaffected salt marsh (115W 

 to 14QW). Beginning in November 1977, there were frequent small-scale over- 

 washes during spring tides. Major overwashea occurred on IS ttovesber 1977 and 

 6 and 7 February 1978. The 9 January 1978 northeaster, vshich caused large- 

 scale overwash along other areas of Nauset Spit-Eastham, did not result in 

 overwash at site 1. The entire site was surveyed before the storm in February 

 in order to calculate accurately the amount of sand deposited by overwash 

 without interference from aeoliart processes. Sand plugs set in August 1977 

 were excavated after the February 1978 northeaster. 



41 



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