(Prather and Sorensen, 1972); Morton (1977) summarized long-term changes 

 occurring after jetty construction at Freeport Harbor and Galveston Bay 

 entrances and Sabine Pass. Price (1947, 1951, 1963) also published exten- 

 sively on inlet processes along the Texas coast. Hydraulic data have been 

 documented primarily by the Corps of Engineers and the Texas Water Development 

 Board (usually under contract), although the National Ocean Survey (NOS) and 

 the U.S. Geological Survey (USGS) have extensive unpublished data. 



3. Summary of Factors Affecting Texas Coast Inlets. 



The significant environmental factors controlling the size, shape, and 

 stability of a tidal inlet are the astronomical tide characteristics, the wave 

 climate and related longshore sediment transport rates, bottom sediment type 

 and size, and storm-induced water level changes, whether by wind effects or 

 increases in freshwater flow into the bays. 



a. Tides. The average diurnal gulf tidal range of about 2 feet produces 

 maximum currents between 3 and 4 feet per second through most inlets on the 

 Texas coast. Monthly and seasonal variations in tide level and range have 

 been found to affect the stability of Corpus Christi Pass (Behrens, Watson, 

 and Mason, 1977) and probably most other inlets as well. Deposition usually 

 occurs during low mean tide levels in the winter and summer, and erosion 

 during high levels in the fall and spring. There is also correlation between 

 deposition and decreasing tidal ranges and erosion and increasing ranges. 



b. Wave Climate. The wave climate along the Texas coast is generally 

 mild with an annual average significant height of about 1.5 feet and a mean 

 period of about 6 seconds at Galveston (Thompson, 1977). Estimates of 1974-77 

 longshore sediment transport rates, based on visual observations of wave 

 height, period, and direction (Fig. 1), indicate net southwestward transport 

 throughout the study area and agree with the direction of net longshore 

 currents measured concurrently, as well as with historical conclusions on net 

 transport direction. 



c. Sediment Type and Size. Sand along the Texas coast is finer than on 

 other U.S. coasts, ranging generally between 0.15 and 0.20 millimeter, and is 

 the primary sediment found at San Luis, Galveston, and Rollover Pass. 

 However, muds and silts predominate at Sabine entrance and, to some extent, at 

 Freeport; large-scale depositional features are significantly different. 



d. Storms. During the winter, strong frontal systems (northers) signifi- 

 cantly influence the stability of most Texas coast inlets. Before the arrival 

 of the front, strong southerly winds usually produce larger than average 

 waves. Upon arrival, north winds rapidly drive large volumes of water south 

 or southwestward along the bays and out of the inlets, causing extensive 

 channel scouring. Price (1951) noted that stable inlets are usually at the 

 southwestern ends of the Texas bays and attributed this stable position to the 

 norther-induced ebb flows described above. However, the net southwesterly 

 longshore sediment transport could also contribute to this preferential 

 location. 



Hurricanes are perhaps the single most important factor controlling the 

 Texas inlet and beach changes, but the lack of quantitative hydraulic data and 

 prestorm and poststorm inlet and beach bathymetries prohibits a detailed 

 assessment of their effect. 



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