landward trajectory of surface currents and the flow of ocean water into 

 the Chesapeake Bay entrance. 



The Atlantic coast of the Delmarva Peninsula has a semidiurnal tide 

 (two highs and two lows each day) with a range of about 1 meter (3.5 

 feet) . The extreme range (spring tide) is on the order of 4 meters (12 

 feet) , ranging from 1 meter below low water to 3 meters above low water. 

 When these peak tides are accompanied by waves, especially storm-generated 

 waves, the actual water level may be significantly higher. 



Wind-generated waves and currents are probably the most important 

 hydrodynamic factors affecting the form and character of the inner shelf 

 and shoreline. Resio and Hayden (1973) studied waves generated by various 

 types of northeasters (extratropical storms--classification based on storm 

 track, speed, pressure, etc.). They found that average surf height maxi- 

 mums obtained from published data for 1955 to 1965 for various storms 

 range from 1 to 2 meters (3 to 6.1 feet). In contrast, the average 

 breaker height during the same time period was 0.55 meter (1.81 feet), 

 as determined from more than 22,000 observations. The Delmarva Atlantic 

 coast is open to attack by both tropical storms (hurricanes) and extra- 

 tropical storms (northeasters). Hurricanes are generally the most severe 

 type of storm along Delmarva (U.S. Army Engineer District, Baltimore, 

 1972); major hurricanes struck the study area in 1933, 1938, 1944, 1954, 

 1955, and 1960. Although many such storms undoubtedly occurred before 

 the 1933 hurricane, this hurricane was most destructive and was respon- 

 sible for breaching the barrier island to form Ocean City Inlet. North- 

 easters, so-called because the winds blow from the offshore northeast 

 quadrant, have milder winds associated with them but are usually of 

 longer duration. The longer time period results in a piling of water 

 against the coast (storm surge) superimposed upon the daily high tides. 

 The most devastating storm of this type was the March 1962 storm that 

 persisted through five high tides and left the coast from North Carolina 

 to Massachusetts as disaster areas. 



II. TOPOGRAPHY OF THE DELMARVA CONTINENTAL SHELF 



1 . Morphologic Elements of the Shelf . 



The general configuration of the major physiographic features of 

 the Atlantic continental margin has been known for over a century (Schopf, 

 1968), but it is only since the advent of echo sounding, in the late 

 1920' s, that the details of the sea floor could be charted efficiently 

 and accurately (Emery, 1966). Until that time lead-line surveying had 

 successfully delineated depths of major basins, banks, plateaus, terraces, 

 and nearshore navigation hazards. However, the paucity of soundings pro- 

 hibited accurate delineation of form and interpretation of processes. 

 Veatch and Smith's (1939) study of the shelf and slope topography in the 

 middle Atlantic Bight is recognized as the first comprehensive and signif- 

 icant work of this type. Since their study, numerous investigators have 

 sought understanding of specific features of the sea floor (Emery, 1966; 

 Uchupi, 1968). On the Continental Shelf, much effort has gone toward the 



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