January, sediment was not moved far offshore and neap berms appeared 

 several days after the storm; however, during the February storm, sedi- 

 ment moved far enough offshore to preclude neap berm formation. Immedi- 

 ate poststorm accretion in this instance is accomplished by small-scale 

 ridge and runnel systems migrating landward. 



IX. CONCLUSIONS 



An analysis of summer and winter process measurements and changes in 

 beach morphology during both investigations reveals the following simi- 

 larities and differences between the two periods. 



1. Detailed beach profiling for summer and winter periods shows no 

 typical summer or winter beach profile at Plum Island. Beach morphology 

 differs from summer to winter; however, the difference is due to the 

 stage of development of the beach profile in relation to storm effects. 



2. Adjacent profiles at different stages of development are thought 

 to reflect the proximity of the nearshore bar (Fig. 17) . The closer the 

 bar is to shore, the faster the sediment is returned to the beach zone 

 after a storm; hence, a profile can quickly develop. 



3. The passage of high- and low-pressure systems through the area 

 during either season produces identical results in wind direction, wave 

 conditions, and longshore current directions. 



4. High-pressure systems during the winter months are of greater 

 intensity than those in the summer months. This results in a stronger 

 offshore wind component during the winter which moves larger amounts of 

 sediment from land toward the sea. 



5. A beach process unique to the winter periods is the limiting 

 effect of ice on erosion. 



6. Local winds control most beach process variables in the summer 

 and winter, except for offshore disturbances which generate the long- 

 period swell measured on several occasions. 



7. Changes in breaker power and wave steepness result in rapid 

 changes in the high tide beach-face gradient, often within several hours, 



8. Changes in breaker height and tidal stage result in changes in 

 ground water elevation. These changes in ground water elevation lag 



1 to 3 hours behind other process variable changes. 



9. Poststorm beach recovery is rapid even after a severe north- 

 easter. The intensity of a storm apparently dictates the accretional 

 processes which rebuild the beach. A small storm will be followed by 

 beach accretion through neap berms; however, after a severe storm, land- 

 ward ridge and runnel migration is the immediate accretional response. 



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