t= Time After Placament 
G = Aiongshore Ditlusivity 
REMAINING IN FRONT OF 
LOCATION PLACED 
= 
a 
2 
iL 
Ww 
Oo 
z 
ie) 
= 
ea 
{e) 
a 
fo} 
iv 
a 
Figure 26. Proportion of material remaining, M, in region placed (from National 
Academy Press 1995) 
Numerical Approach 
The analysis summarized in this section involves the application of the 
GENESIS (Hanson and Kraus 1989) shoreline evolution model to further 
investigate the processes that have caused the rapid loss of beach-fill material 
from the Monmouth Beach hot-spot area. As idealized in the previous analytical 
approach, the Monmouth Beach hot spot is viewed as a short beach fill super- 
imposed upon a larger beach fill. The GENESIS model was set up with a 
20,505-ft (6,250-m) model domain containing a 4,100-ft- (1,250-m) long beach 
fill located in the center of the model domain. The initial berm width of the 
beach fill was specified as being 278 ft (85 m), estimated from the initial volume 
of beach-fill material placed between sta 264 and 282. The GENESIS model 
was calibrated to the measured volume losses using the effective wave height at 
the Long Branch wave gauge (#7, = 2.0 ft (0.6 m), 8 = 0 deg). With the 
idealized shoreline and effective wave conditions, the GENESIS model was 
calibrated (GENESIS calibration coefficients, K, = 0.93 and K, = 0.5) such that 
37 percent of the fill material would be lost from the hot spot in the first 
13 months after placement. 
Having calibrated the GENESIS model to the available measurements, 
model simulations were performed using four different 1-year-long time series of 
wave conditions measured at the Long Branch directional wave gauge. These 
simulations resulted in a more realistic time sequence of shoreline evolution 
(e.g., more rapid losses during energetic wave events associated with winter 
Chapter 4 Beach-Fill End Losses 
33 
