buildup of dredged disposal material in the offshore dumping zone, and the low 

 rate of offshore erosion versus annual dredging rates (600,000 versus 

 1,450,000 cubic yards per year, respectively), further studies are required to 

 determine the major source of channel deposits. Consideration should also be 

 given to monitoring the current flow and circulation in Freeport Harbor, 

 particularly the effects of cooling water withdrawal by Dow Chemical Company. 



3. San Luis Pass. 



a. Bathymetric Changes. The present site of San Luis Pass has been open 

 since at least 1834. This equilibrium condition is exemplified by the fact 

 that only minor changes in sediment volumes occurred on the ebb and flood 

 tidal deltas between 1853 and 1933. However, the inlet cross-sectional area 

 and width have generally been increasing since 1853, which agrees with O'Brien 

 and Dean's (1972) theoretical stability analysis indicating San Luis Pass to 

 be on the unstable side of the critical cross-sectional area. 



The shoulders of the inlet (within the influence of the ebb tidal delta) 

 show frequent short-term changes, but the present trend is one of accretion on 

 the west shoulder and erosion on the east. The deepest part of the inlet 

 throat has always been on the west (downdrift) side; the outer part of the 

 channel has usually been oriented at about 90° to the shoreline trend. 



Both the ebb and flood tidal deltas contain sufficiently large volumes of 

 sand to serve as beach nourishment borrow areas. Dredging of material from 

 the relatively protected landward edge of an east coast ebb tidal delta has 

 been accomplished in recent years by the U.S. Army Engineer Division, South 

 Atlantic. Similar operations are feasible at San Luis Pass, but sand samples 

 should be obtained from throughout the inlet complex to determine the loca- 

 tions of optimally sized sediment. 



b. Tides and Hydraulics . Tides at the San Luis Pass bridge, although in 

 phase with those at the Galveston Pleasure Pier, exhibit only about 75 percent 

 of the pier's range. Bay tidal ranges are slightly more than 50 percent of 

 the bridge range and show greater than expected phase lags. The average tidal 

 prism was 1.65 x 10^ cubic feet, and it was found that computations of the 

 prism using the bay tidal range and bay area relationship given by equation 

 (6) agreed well with the discharge method. Measured mean currents through the 

 inlet throat were about 2 feet per second, although higher currents will occur 

 during diurnal tides. Slight increases in the tidal prism will occur in 

 future years if the predictions of increased inlet cross-sectional area and 

 maximum velocity are correct. 



4. Galveston Bay Entrance. 



a. Bathymetric Changes . Extensive changes to adjacent beaches and the 

 entrance channel have occurred since construction of the Galveston entrance 

 jetties. On the updrift side, sediment has been depositing at a relatively 

 constant rate of about 430,000 cubic yards per year. On the downdrift (south) 

 side, an adjustment of the ebb tidal delta to the altered wave and current 

 conditions resulted in a tripartite pattern of deposition offshore and in the 

 fillet, and erosion between these zones; this pattern was apparently completed 

 by 1933. Subsequent changes to the south side have been minor, although the 

 shoreline slowly moved gulfward between 1933 and 1965. The minimum width of 



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