were 1:1000 horizontally and 1:100 vertically. These scales were se- 

 lected on the dual basis of providing the largest model that could be 

 justified from a cost viewpoint, as well as the smallest model that coiild 

 be tolerated from the standpoint of accurate reproduction and measure- 

 ment of significant phenomena. Use of the above linear scales fixed the 

 following significant scale relationships (model to prototype): velocity, 

 1:10; time, 1:100; plan area, 1:1,000,000; cross- sectional area, 1:100,000; 

 discharge, 1:1,000,000; and volume, 1:100,000,000. 



Description of Model 



13. The prototype area reproduced in the Narragansett Bay model 

 is shown on fig. 1. The ocean area reproduced outside the bay entrances 

 extended from Point Judith on the west to Sakonnet Point on the east, 

 and included most of Rhode Island Soiond. Offshore hydrography in the 

 ocean was reproduced in detail to the 100-ft contour of depth, and the 

 ocean area beyond this contour was utilized for the astronomical tide 

 and hurricane tide generators which are described subseq^uently. All of 

 the inner bay system was included in the model, as well as the tidal 

 portions of all streams tributary to the bays as far upstream as signif- 

 icant flooding by hurricane tides of record had occixrred. 



ik. The model was of fixed-bed construction throughout, the bed 

 and banks being molded of concrete. The hydrography of the bays and 

 tributary streams was molded carefully in accordance with information 

 shown on the latest hydrographic surveys made by the Coast and Geodetic 

 Survey and the Corps of Engineers. The topography of the banks adjacent 

 to the bays and tributary streams was molded in detail to el +32 ft mlw 

 at Newport, R. I., in accordance with topographic surveys prepared by 

 the Geological Survey, so that the extent of flooding by hurricane tides, 

 as well as the storage effect of such flooding on water- surface eleva- 

 tions at upstream localities, could be reproduced with maximum accuracy. 

 Fig. 2 is a general view of the model; a close-up of the Providence 

 Harbor area is shown on fig. 3* 



