



Deep Water Wave Angle of Approach = 157.5° from North 













512500- 





1 \ c '^--x^'X 





■ 



70ft 

 65 ft 



"J, * \. ^s. 





1 







\ * |X x^ 







60ft 















' 



55 ft 

 50 ft 





512000- 



c 



2 511500- 







V< - 







45 ft 

 40 ft 

 35ft 

 30ft 

 25ft 

 20ft 

 15ft 

 10 ft 



1 



z 

 •& 



-O 



S 



a 



511000- 





1 ilk 









5ft 

 Oft 



-5ft 









igjSk 







-10 ft 









\ W^ll 6 - 









1384 



€00 



1365000 1385500 1366000 1366500 



1367000 





Easting (ft) 









> =3.0 ft Significant Wave Height 





Figure 31. RCPWave wave-refraction diagram in the vicinity of Norriego Point 



If the hypothesis is valid, a solution to this type of problem is to address the sediment 

 source. The hydrodynamic analysis indicated that the currents alone were incapable of 

 creating the shoal. Therefore, reducing the wave-suspended/transported sediment is the 

 appropriate approach to this problem. Either a reduction in wave activity or a reduction 

 in the actual transport may address this shoaling problem. Reducing the wave activity 

 would involve the construction of a breakwater either outside the jetties (preventing 

 waves from entering the throat) or directly offshore of the point. Obviously, construction 

 within the throat is less costly than construction offshore. In addition, a breakwater 

 aligned with the channel and close to shore would have a much smaller impact on the 

 tidal hydraulics than would a breakwater outside the jetties. 



Several actions would reduce the actual sediment transport. First, hardening the 

 shoreline will prevent sediment movement and thus shoaling. Hardening can take the 

 form of either a seawall or revetments. Second, the sediment may be intercepted before it 

 reaches Old Pass. The construction of a small terminal structure at the tip of Norriego 

 Point would trap the sediment as it moves north. 



In conclusion, the application of the tools in the DMS-Analytical Toolbox have 

 successfully clarified the classification of one of the two problem areas that fell under 

 more than one shoaling category. The analysis of the second area provided more insight 

 into the physical processes that create the shoal. However, the analysis also pointed out 

 deficiencies in the toolbox that require improvement. 



50 



Chapter 4 DMS-Analytical Toolbox 



