that (1) currents decrease in velocity with an increase in depth, (2) the strong- 

 est longshore currents occur at the Tj -fathom stations located off Galveston 

 and San Luis Pass, and (3) although a few 2-knot currents were observed, the 

 majority were less than 1 knot at all stations. 



The purpose of the 24-hour current studies conducted in June, July, 

 and August at Station H were twofold: (1) to check the validity of the instan- 

 taneous monthly readings and (2) to measure the residual current and deter- 

 mine, if possible, the influencing factors. Analysis of the first 24-hour 

 current study substantiated the belief that instantaneous readings, although 

 measuring the direction and speed of the current at that time, could conceiv- 

 ably result in an erroneous concept of the residual current. 



Further analysis of the data indicated that if continuous monthly ob- 

 servations could be made at a permanent station, a residual monthly current 

 pattern could be established. It should then be possible to relate existing re- 

 sidual currents directly to some physical factors, such as water density, winds, 

 or tides. 



Progressive vector analysis of the currents at three depths during 

 the June study revealed a wide current variation between depths. The vector 

 diagrams for the surface and bottom, currents strongly suggest currents in- 

 fluenced by tidal action. Some discrepancies exist, however, between the 

 noted changes at Station H and the tidal gauge at the Galveston Channel. The 

 distance between these two points (48 nautical miles) probably accounts for 

 these anomalies. Mid-depth currents (45 feet) appeared to be less subject to 

 these tidal changes. The resultant currents at the three depths were variable. 

 The current at 10 feet was moving 287° at 1.7 knots, the 45-foot current flow- 

 ing 226° at 4.4 knots, and the 80-foot current flowing 133° at 1. 5 knots. Dur- 

 ing this period, a 10-knot southeast wind prevailed. 



In the July and August studies, the variations noted in June were not 

 evident. In July, all depths exhibited an easterly current with the velocity de- 

 creasing as depth increased. Prior to the July observations, a south to south- 

 east wind averaging 11 knots had prevailed for 8 days. The water currents, 

 moving to the right of this force, were probably a direct result of these winds. 



The curtailed August observations revealed a similar picture. Cur- 

 rents at all three depths, flowing southerly, appear to be the result of a north 

 to northeast wind averaging 10 knots which had prevailed for 6 days prior to 

 the observations. 



Fronn these limited data, it is impossible to establish a monthly cur- 

 rent pattern for either June, July, or August. Utilizing clinaatological data 

 and Galveston Channel tide tables, however, we could detect relationship be- 

 tween observed currents during a 24-hour period, winds, and tides. Indica- 

 tions were that currents 48 nautical miles south of Galveston are influenced 

 by tide and wind action. 



In February 1962, the current study utilizing the Savonius rotor 

 current meter was expanded by the addition of drift bottles and seabed drifters. 

 Twelve drift bottles, six of which are ballasted with sand, and six seabed 

 drifters are released at each of the 60 monthly stations. 



24 



