b. Storm Effect on Profile Shape . Although a number of storm events oc- 

 curred, the only significant profile change to be documented was that associated 

 with a mid-September northeaster (14 to 16 September), the largest coastal storm 

 that had occurred during the study up to that time. Before the mid-September 

 storm, the predisposal surf zone trough had been filled and the surf zone bar 

 eliminated. No other bar developed in the study area other than the disposal 

 bar and a very small, local ephemeral bar in the offshore zone CFig. 15, range 

 -1+00) . The disposal bar had built laterally, presumably in response to bar- 

 induced wave breaking and transport along the bar axis. 



A survey was conducted on 16 September during the waning phase of the Sep- 

 tember storm. Average breaker height during the storm was 1.5 meters and 

 breaker period was 6 seconds. A strong, southwest-directed longshore current 

 (average speed = 65 centimeters per second) and coastal current resulted from 

 the easterly wave approach and wind effects . 



Although distinct changes in profile shape occurred, the pattern was not 

 uniform throughout the study area. The two stormward (northeast) disposal pro- 

 file ranges -3+00 and -4+00 show that the upcurrent end of the disposal bar was: 

 eroded to form a nonbarred or a slightly barred (erosional remnant) profile 

 (Fig. 15). In neither of the two northeastward native, nonbarred profile ranges 

 -1+00 and -2+00 nor the two eroded disposal bar profile ranges -3+00 and -4+00, 

 did a bar build seaward or was one displaced seaward as generally might be ex- 

 pected for storm erosion conditions. All downcurrent (southwestward) profiles 

 showed the disposal bar remained but underwent significant modification. A mass 

 of sediment accreted to the landward flank of the disposal bar of several adja- 

 cent, downcurrent profiles (ranges -5+00, -6+00, and -7+00). This resulted in 

 partial filling of the disposal trough and elimination of the asymmetric form 

 of the disposal bar. Where such trough filling occurred, the longshore current 

 cut a new, slightly landward "channel wall." Farther downcurrent, similar bar 

 accretion and trough filling did not occur, but well-developed troughs were cut 

 deeper into the already developed disposal bar trough, or the disposal platform. 

 In this downcurrent location, accretion did occur on the lowermost foreshore and 

 landward side of the inshore zone (ranges -8+00, -9+00, and -10+00). In plan 

 view, the trough thus became larger and shifted seaward toward the disposal bar 

 in the downcurrent direction. A small amount of modification occurred on the 

 disposal bar's seaward flank at ranges -5+00 to -8+00. At the farthest down- 

 current end, the disposal bar showed lateral growth or extension onto adjacent 

 profiles (ranges -9+00 and -10+00) . 



Of the six storms which occurred between mid-September and mid-October, the 

 largest occurred 10 days before the mid-October survey. A smaller storm occurred 

 3.5 days before the survey. Therefore, poststorm transport had at least some 

 time to modify the 19 October storm profile. The pattern of profile change was 

 reversed somewhat from that following the September storm. In general, the 

 eroded disposal bar along the northeast ranges -3+00 and -4+00 was partially re- 

 built and accretion occurred on the outer flank of the disposal bar for ranges 

 -5+00 to -8+00. In addition, the bar extended even farther northeastward onto 

 range -2+00, where it previously had not occurred. As before, no bar occurred 

 on range -1+00. Some of the sand which partially filled the northeastward part 

 of the trough following the September storm was eroded. The bar along the south- 

 westernmost ranges -9+00 and -10+00 remained essentially unchanged, but the 

 trough had filled in, resulting in a platform shape across the inshore zone. 



28 



