Tide and current data measured over a 15-hour period were obtained by SWG 

 in February 1962 for use in calibrating a physical model of Galveston Bay. 

 Only two current stations in the throat were occupied; velocities were meas- 

 ured every half hour at three depths: usually 1, 7, and 13 feet. 



Current speeds were again measured for 28 hours by SWG between 4 and 5 May 

 1965 for the physical model in the Texas Coast Hurricane Studies. Measure- 

 ments were made at only one station in the throat at four depths: 2, 7, 12, 

 and 18 feet. An SWG tide gage at Sea Isle Marina in West Bay was operational 

 from 14 August 1964 to 3 January 1968, providing an analog record of the bay 

 tide. 



Several tide gages were operational between September and November 1965: 

 NOS gage at Jamaica Beach in West Bay and the Galveston Pleasure Pier, SWG 

 gages in Chocolate Bayou (26 August 1964 to present) and Sea Isle Marina. 



In July and August 1969, tide measurements were made by NOS in Christmas 

 Bay, West Bay (Alligator Point) , and at the Pleasure Pier. Analog records for 

 1974 were obtained for the SWG San Luis Pass and Chocolate Bayou gages, as 

 were tabulated highs and lows for the NOS Galveston Pleasure Pier gage. 



On 24 June 1976, current measurements between 1300 and 2400 hours were 

 made by Espey, Huston and Associates to obtain a rating curve for the pass 

 (Johnston and Ward, 1976). Three stations were occupied in the throat of the 

 pass. From these data, a discharge versus center velocity curve was developed 

 for future measurements. Espey, Huston and Associates reoccupied the center 

 station in the throat between 20 and 23 July 1976, and obtained hourly meas- 

 urements, usually at five depths, with occasional readings at the bottom. 

 Concurrent tidal data were available from the SWG gages at the pass and 

 Chocolate Bayou. 



(2) Data Analysis and Results . The objective of the hydraulic data 

 analysis was to determine the tide characteristics, currents, and discharges, 

 along with friction and discharge coefficients. 



(a) Tidal Ranges and Levels . Table 2 summarizes the available 

 information on tidal ranges throughout the inlet-bay system. West Bay 

 (including Chocolate Bayou) and Christmas Bay respond similarly to the gulf 

 tide; i.e., the tidal range in each bay is about 0.45 that at the Galveston 

 Pleasure Pier. The 1974 average annual San Luis Pass range is about three- 

 fourths that of the pier, indicating some energy loss over the ebb tidal 

 delta. The pattern of 1974 monthly variability in tidal range for the San 

 Luis Pass gage (Fig. 5) was considerably different from that of Chocolate 

 Bayou and the Pleasure Pier, presumably the result of meteorological effects 

 at the pass since the pattern of range variability due to astronomical causes 

 more closely approximates the Chocolate Bayou pattern. The monthly tide level 

 variability patterns (Fig. 4) are similar to those of other gulf coast 

 locations. 



(b) Tidal Phases . Phase information is useful in analyzing the 

 hydraulics of an inlet bay system. Concurrent tidal data from 15 to 30 July 

 1969 were analyzed to determine the phase lags between high and low waters at 

 several locations; the results are summarized in Table 3. High and low waters 

 occur almost simultaneously at San Luis Pass and the Galveston Pleasure Pier. 



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