i 2 



T I I I I I I r 



T I I I I I I 



Locus of Ac critlcol 



J I I I I I I 



L,: 43,000 ft 

 It Location of A; and Vi^ox for Dote Shown 

 I I I I I I'll 



5,000 10,000 50,000 



Minimum Cross- Sectional Areo, A^ (ft') 



Figure 82. 



area predicted by Figure 82. Thus, O'Brien and Dean's (1972) method shows 

 Sabine to be near equilibrium; Jarrett's (1976) method indicates that the 

 channel should be shoaling. 



e. Summary. Sabine Pass is an anomalous inlet compared to the other 

 inlets in the study area. Sediments in the inlet and on the adjacent beaches 

 are very fine silts and mud; freshwater outflow affects the vertical distribu- 

 tion of flood and ebb currents and may produce density currents which influ- 

 ence depositional patterns. Although the Sabine and Neches Rivers probably 

 transport sand-sized material to their mouths, Sabine Lake acts as a filter 

 and prevents this sediment from reaching gulf beaches. Even with this differ- 

 ence in sediment, changes following jetty construction followed the same 

 pattern as at Galveston: downdrift deposition offshore and in the fillet, 

 with erosion in between, and updrift deposition. Unfortunately, the lack of 

 sufficient survey data precluded analysis of changes in the cross-sectional 

 area at Sabine Pass. However, it appears that construction of the jetties 

 with small-boat passes has increased the natural scouring capacity of tidal 

 currents by establishing an ebb flow predominance between the jetties. This 

 scouring is particularly accentuated during the passage of northers, when 

 instantaneous discharges three times those of normal diurnal tides produce ebb 

 currents in excess of 6 feet per second (Ward and Chambers, 1978). 



IV. SUMMARY 

 1. Tide Characteristics. 



Tide data from a number of SWG and NOS gages throughout the upper Texas 

 coast revealed the following characteristics: 



(a) Long-term variability in monthly mean tidal range and water 

 level is uniform throughout the area, with two maximums and two mini- 

 mums per year. Annual variabililty in range is small (16 percent). 



90 



