ERDC/CHL CHETN-IV-61
December 2003
physical model results discussed later will illustrate this. Field data from Table 1 were used to
compose the plot in Figure 8. A S/L ratio (S is spur length and L is distance from spur to the
local average shoreline) is plotted for each field site. A shoreline response ratio was determined
from the ratio of distance from the local average shoreline (defined as the shoreline within 300 m
of the jetty) to the immediate shoreline at the jetty, divided by the distance from local average
shoreline to the spur. Therefore, a shoreline response of 1.0 means the shoreline has reached the
spur. This is seen for Bakers Haulover and Shark River, with S/L ratios greater than 0.4. The
others have S/L less than 0.4 and shoreline responses much less than 1.0. In this simplified ap-
proach that may neglect other important parameters, such as beach slope and wave height, a line
was drawn at S/L = 0.4 to divide from full shoreline response and a partial shoreline response.
Typically, one would not want the shoreline to reach the spur in order to keep the potential for
sand transport to the sea side of the spur minimal. If the wave climate is not too energetic or if
the spur is on the downcoast side of a jetty system where sediment is bypassed to, it might be
acceptable. On the other hand, one needs to have a long enough spur to create a deflection of the