Subaerial changes included the following: 



a. The ovenvashing of Santa Rosa Island and the landward side of the west 

 jetty, an action that led to the creation of a large depositional fan in the 

 lee of the island and the accumulation of sand in the area previously 

 occupied by the deposition basin. 



b. The breaching of Norriego Point with deposition of sediment in Old Pass 

 Lagoon. 



c. The overwashing of the beach east of the east jetty, an action that 

 flattened dunes and carried sediment into the area eroded near the spur 

 jetty and further into the thalweg of the channel. 



d. Minor damage to the jetties involving the settling of the capstones. 



Morphological subaqueous changes associated with the ebb jet and post- 

 recovery included the following: 



a. The formation of a contraction-induced scour hole at the inlet throat 

 between the jetties. 



b. The westward movement of the thalweg away from the shoreline and 

 subsequent channel straightening. 



c. The further deepening of the scour holes at the tips of the west jetty and 

 spur jetty. 



Notably, Hurricane Opal caused no significant change in the ebb shoal's 

 growth pattern. In contrast to this assessment, the local US ACE office reported 

 no apparent deepening of the scour holes as a result of Hurricane Opal. More 

 information concerning the damage caused by Hurricane Opal is contained in 

 Leadon, Nguyen, and Clark (1998) and Leadon (1996). 



The preceding account of the history of the inlet has accomplished three 

 goals. First, it pointed out the need for the DMS system. Considerable money 

 and effort have been expended at East Pass to improve the navigational safety of 

 the Federally maintained channel. The use of the DMS at certain stages in this 

 channel's history may have pointed to better solutions than the ones attempted 

 (e.g., the weir jetty). Second, it validated the choice of East Pass — a location 

 where maintenance efforts have expended considerable time and money — an 

 appropriate demonstration site for application of the DMS methodology. Finally, 

 it has familiarized the reader with the study area to facilitate later discussion. 



East Pass - physical processes 



Knowledge of the physical processes in the study area also aids in the 

 diagnosis of shoaling problems. Notably, the DMS intends to address the 

 mechanisms that cause shoaling rather than simply treat the shoaling itself. In 

 this regard, application of the DMS is a proactive rather than the traditional 

 reactive approach to addressing shoaling. As such, knowledge of the channel's 

 physical processes that cause the shoaling is essential in finding a defensible and 

 successful shoaling mitigation method. This section characterizes the physical 

 processes at East Pass through a literature search. 



To comprehend an inlet's tidal hydrodynamics, one must document not only 

 the tidal ranges and their consequences but also the influences of bay geometry, 



Chapter 1 Background and Problem Statement 



