42 
south of sta 255 lost significant volumes of material. The loss of material from 
the hot-spot region and the corresponding gain of material in the region to the 
north support the theory that beach-fill end losses play an important role in the 
development of the Monmouth Beach hot spot. 
Proceeding in time to the October 1995 bathymetry (Figure 31), the beach 
fill for Contract 1A has proceeded north and is nearing completion. In the hot- 
spot region, additional erosion of beach-fill material has left the area with a much 
narrower beach and consequently less protection against storms. The erosion of 
the protruding beach fill has resulted in the evolution of the shoreline to a shape 
and orientation similar to that of the -20-ft contour of the prefill condition 
(Figure 278). This adjustment of the beach fill to a more “natural” configuration 
through the longshore transport of material apparently contributed to the 
development of the hot spot at Monmouth Beach. Also, from Figure 31, it 
appears that the most severe erosion within the hot-spot region (found at sta 275) 
is partially due to the downdrift effect of Coastal Structure 45 located at sta 277. 
Evolution of the mhw shoreline over the construction cycle of Contract 1A 
illustrates the relationship between the loss of material from the hot-spot region 
and the gain of material downdrift. Figure 32 presents the mhw shorelines for 
February 1993 (prefill), October 1994, March 1995, October 1995, and April 
1996 (sparse monitoring survey data are also presented for April 1996). The 
evolution of the mhw shoreline illustrates the smoothing effect of longshore 
transport on the shoreline perturbation presented in the construction of the beach- 
fill planform. The beach width, relative to the beach-fill reference line (or 
seawall), north of the hot spot has increased at the expense of the beach width 
within the hot-spot region. 
Additional support of the beach-fill end-loss hypothesis is found in an 
elevation difference plot between the October 1994 and March 1995 bathymetric 
models (Figure 33). In this plot, the loss of material from the northern portion of 
the hot-spot region is evident along with material placed between October and 
December 1994 near sta 245. The elevation gained in the 3,200-ft alongshore 
region between sta 208 and 240 represents a significant volume of material— 
material presumably transported from the hot-spot region. Coverage of the 
October 1994 beach profile surveys is insufficient to determine volume lost from 
the hot spot versus volume gained in the adjacent region to the north. 
Chapter 5 Beach-Fill Planform Adjustment 
