2.3. Relevant Coastal Processes 



This section gives an overview of the coastal processes acting at the properties of the 

 plaintiffs, focusing on those relevant to this study. Coastal processes impacting sediment 

 transport along the beaches of Brevard County include long-term wave and current dynamics; 

 short-term, high-energy storms; and relative sea-level rise. All these factors produce beach 

 erosion and accretion along the Brevard County coast. 



2.3.1. Sediment Transport 



Longshore sand transport primarily acts on the portion of the beach below the toe of the dune, 

 called the beach berm and foreshore. Longshore transport can advance the shoreline at a given 

 location (accrete the beach) if more sand enters than leaves the area, or it can cause the shoreline 

 to recede (erode the beach) if more sand leaves an area than enters. Cross-shore sand transport is 

 primarily associated with destructive conditions (i.e., dune and/or beach erosion by storms). 

 Sand removed from the dune and berm may then be transported out of the area of erosion by 

 longshore transport. Also, sand removed from the dune and upper beach may be partially 

 deposited on the lower portion of the beach, producing a seaward advance of the shoreline. The 

 Harbor channel and jetties interrupt longshore sand transport, but the Harbor does not alter cross- 

 shore sand transport processes. Both of these processes are water-borne transport, as 

 summarized in Table 2-2. 



Table 2-2. Comparison of longshore and storm-induced cross-shore transport processes. 



Process 



Longshore Sand Transport 



Storm-Induced Cross-Shore 

 Sand Transport 



Dominant 

 Forcing 



Waves arriving to the coast at an 

 oblique angle 



Elevated water level and high waves with 

 longer periods than non-storm waves 



Time Scale 



Months, years, decades 



Hours to days for extreme events (storms 

 and hurricanes); seasonal for regular 

 annual change 



Region of Beach 

 Profile Impacted 



Primarily beach berm, foreshore, 

 and surf zone 



Dune, berm, and foreshore 



Typical Result 



Shoreline recession or advance; 

 beach erosion or accretion 



Recession of the beach and dune face 

 and loss of sand volume 



2.3.2. Waves 



The USACE Wave Information Study (WIS) (Hubertz et al. 1993) has performed a wave 

 hindcast for the Atlantic Ocean coast of the United States. The hindcast covers the period 1956- 

 1975 and involved generating waves with a numerical model with input forcing by wind and 

 pressure fields measured in the Atlantic Ocean. WIS Station 18, located south of Cape 

 Canaveral, is the nearest to Canaveral Harbor (Latitude 28.25 N, Longitude 80.25 W) at 22-m 

 water depth (see Figure 1-1). The average monthly significant wave height in the 20-year 



2-8 



Chapter 2 Background 



