Jarrett's (1976) relationship between equilibrium cross-sectional area and 

 tidal prism gives an equilibrium area of 4,400 square feet for the 1971 tidal 

 prism, which is considerably larger than the minimum area has ever been at the 

 pass. Thus, without the weir section in the throat, the inlet could be 

 expected to resume its initial unstable scour mode. 



f. Summary . The construction of Rollover Pass has affected the adjacent 

 downdrift beach, producing a deficit of about 26,000 cubic yards per year in 

 the net longshore sediment transport rate. The minimum cross-sectional area, 

 about 875 square feet, has remained relatively constant, although the seaward 

 part of the pass experienced extensive deposition in recent years. Unfortu- 

 nately, the lack of long-term velocity data in the pass precludes determining 

 the predominance of flood or ebb flows, as well as an accurate portrayal of 

 the current speed characteristics. Limited sand-size distribution data indi- 

 cate that material deposited in Rollover Bay is probably finer than that on 

 the gulf beaches. Additional samples should be taken if nourishment of adja- 

 cent beaches with bay shoal material is contemplated. 



5. Sabine Pass . 



a. Historical Review . Sabine Pass, on the Texas-Louisiana border, is a 

 tidal inlet about 7 miles long and 2,000 to 5,000 feet wide, connecting Sabine 

 Lake to the Gulf of Mexico. The Sabine and Neches Rivers empty into the north 

 end of Sabine Lake, contributing an average of 14,650 cubic feet per second of 

 freshwater to the system. During storms, discharges exceed 200,000 cubic feet 

 per second. Unlike the other inlets considered, where sand bottoms predomi- 

 nate, the ebb tidal delta and offshore areas at Sabine Pass are comprised of 

 thick layers of mud. Net longshore transport is to the west. Figure 69 shows 

 the longshore and shore-normal components of the monthly resultant winds for 

 the Sabine Pass (Port Arthur) shoreline orientation for 1973. Note the strong 

 westward longshore component which agrees with the net longshore sediment 

 transport direction. 



2.5 



— 1 1 1 1 1 1 1 1 1 r 



Short-Normol Compofiinl 



— 1 — 



2.0 



l\^^"^ V 



\ 



• 1.5 





\ - 









« 



/ Onshore \ / 



\ 







\ 



o 1.0 





\" 



0.5 



/ / ^ V ' ^ 



\" 



— 



/ /Eostword \ 





-- 



/ ' \ 



/ - 



E 



/ ^--' 



/ 



-0.5 



" ^^ \ Westword 











|-I.O 



A / 



- 



i-15 



Longshore Component 



- 



-z.o 



- 



- 



-25 



1 1 1 1 — 1 — 1 — 1 — 1 — 1 — -i- 



_i — 



-4 9 1 

 S.5 

 -8.2 



Jan. F>l). Mar. Apr. May Junt July Aug. S«pt. Oct. Nav. Otc. 



Figure. 69. Longshore and shore-normal components 

 of monthly resultant wind, Sabine Pass 

 (Port Arthur), Texas, 1973. 



77 



