Model Appurtenances 



15. The major appurtenances utilized in operation of the model^ 

 and for measurement of the required phenomena therein^ included astronom- 

 ical and hurricane tide generators^ recording tide gages, manually oper- 

 ated point gages, current velocity meters, and upland discharge vreirs. 

 These appurtenances and their uses are described briefly in the subse- 

 quent paragraphs. 



16. The astronomical tide generator was of a conventional type 

 used by the Waterways Experim^ent Station in connection with many estuary 

 models. Its major components consisted of an underground water-supply 

 s-ump located near the m.odel, a large header connecting the sump and the 

 ocean portion of the model, a mechanized valve installed in the header, 

 a pumped-discharge line which entered the header on the model side of 

 the mechanized valve, and an electromechanical control system which 

 dictated the opening and closing of the mechanized valve. In operation, 

 the control unit was adjusted to automatically cause precise opening and 

 closing cycles of movement of the valve, which in turn maintained the 

 necessary balance between a pumped flow of water to or a gravity flow of 

 water from the model as required to duplicate the exact rate of rise or 

 fall of the tide being reproduced. This apparatus consistently maintained 

 correct water- surface elevations of the model ocean within an acc\iracy of 

 about 0.001 ft (0.1 ft prototype). The mechanized valve and the valve- 

 control unit are shown on figs, k and 5^ respectively. 



17. Hurricane tides could have been reproduced in the model with 

 the same system used for generation of astronomical tides, or by an in- 

 dependent system of the same type, except that the large amplitude of 

 the hurricane tides would have required the use of very large pumps, 

 valves, and pipes. A study of possible methods of reproducing hurricane 

 tides indicated that the most practical and economical solution would 



be to construct a reservoir (or basin) adjacent to and integral with the 

 model ocean containing a volume of water somewhat greater than that re- 

 quired to reproduce the largest hurricane tide to be studied, and to 

 reproduce the tide by means of a motorized bulldiead in the basin. This 



