b. Analysis of Data . 



(I) Deflation of Dane-Throat Areas . Deflation of washover throats 

 was studied at sites I and 3 on Nauset Spit-Easthara. Site 1 throat was sur- 

 veyed for 18 months after the February 1978 storm to document deflation of 

 washover sediment from an area where all vegetation had been removed. The 

 throat of site 3 washover was studied to document deflation where there was 

 deposition on top of living dune vegetation. 



(a) Site 1 Throat . Daring the February 1978 northeaster, 288 

 cubic meters of sand was deposited at site 1 throat (Fig. 17). The throat was 

 very flat (a - 0.32 meter) , decreasing gradually in elevation west of the berm 

 crest. Only a small remnant of the north vegetated dune and two piles of 

 drift material interrupted the planar feature. Three-dimensional plots of 

 site 1 throat were constructed from survey data collected in April, June, and 

 October 1978 and in June 1979 to illustrate the deflation and overall changes 

 In the throat (Fig. 22). 



Within 2 months, site I throat had lost 194 cubic meters (67 percent) of 

 the washover sediment deposited during the February 1978 storm. The southwest 

 corner of the plot (18S to 24S, 30N to 60W) was deflated by as much as 72 

 centimeters. The prograding edge of a large wind-shadow dune, which developed 

 against the scarped dune south of site 1 throat, appears in the southeast (15S 

 to 24S, Ow to 25w) corner of the plot. The elevation in this area increased 

 as much as 63 centimenters. 



Between April and October 1978, very little change occurred at site 1 

 throat because wind velocities were low. The back and center of the throat 

 continued to deflate and the wind-shadow dune 3nlarged. Only 35 cubic meters 

 of sand was lost between April and June; 78 cubic meters was lost between June 

 and October 1978. 



Between October 1978 and June 1979, site 1 throat lost mother 257 cubic 

 meters of sand for a total of 564 cubic meters, approximately twice the 

 Initial overwash. The berm crest in June 1979 was slightly lower (10 centi- 

 meters) than the berm crest on 5 February 1978 then overwash occurred. A lag 

 layer of heavy cobbles had developed by June 1979, slowing aeoltan deflation 

 of the throat. 



Two years after the 1978 northeaster, site 1 throat had not been stabi- 

 lized by vegetation. Drift line vegetation developed each spring in debris, 

 but these plants were eroded by either aeolian deflation or overwash the 

 following winter. Site 1 throat remained an active washover channel, prevent- 

 ing the closure of the breach in the dune line. 



(b) Site 3 Throat . Site 3 provided a very different set of con- 

 ditions for study. Overwash overtopped the dunes at site 3, eroding the dunes 

 south of the washover channel and 30 meters into the dune line in the center 

 of the plot. Approximately 50 percent of the dunes at site 3 throat were 

 eroded. Three-dimensional plots of site 3 throat were constructed from field 

 surveys conducted in June and August 1978 and August 1979 (Fig. 23). 



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