incident wave height for seabed profiles 1 on 15 or gentler. Waves break- 

 ing at an oblique angle to the depth contours probably produce less setup 

 at the shore. Wave setup is also dependent on the configuration of the 

 foreshore and the configuration of the coastline. An estimate of the in- 

 fluence on wave setup of such irregularities is difficult, and would vary 

 for each different configuration. 



The maximum storm-induced surge at the coast is also affected by 

 the fluid properties over the total depth beneath the storm system. 

 Fluid stratification is present due to the vertical density gradients, 

 and strong currents in the nearshore regions cause bed materials to be 

 propelled into suspension thus increasing the fluid density. Since water 

 is a real fluid, there is lateral friction between the fluid stream lines. 

 Such complexities are generally ignored in estimates of the maximum open- 

 coast surges, although accounted for in some overall gross manner. How- 

 ever, the properties of the fluid are important in the storm generation 

 process, and it is not always completely satisfactory to disregard the 

 various modes of internal motion caused by the disturbance of real fluid. 



The height of the hurricane surge is also governed by the charac- 

 teristics of the basin, such as the size, coastline and bed formation, 

 and the roughness of the Continental Shelf. As mentioned previously, a 

 basin too small for the storm system can cause a reduction in intensity 

 while the storm is positioned far out at sea, thereby reducing the surge 

 at the open coast. The water level at the shore is also dependent upon 

 the hydrographic configurations of the shelf and the shape of the coast- 

 line. Thus, the water level is affected by the presence of submerged 

 barriers, submarine canyons and any other formations which may abet or 

 impede the flow. Normally, there is an amplification of the storm- 

 induced surge wave if the shelf is relatively flat or shallow. However, 

 this may not always be the case, since bottom-friction stresses may 

 predominate over the surface stresses. Bottom stresses are important 

 principally in shallow water and are dependent on the roughness of the 

 seabed in respect to the size of the bottom material as well as the 

 configuration of the bed. When estimating the surge which moves over 

 the low-lying terrain adjacent to the sea, the bottom stresses become 

 extremely important due to vegetation and other obstructions. 



The maximum surge on the open coast is also affected by the astro- 

 nomical tide. The degree of effect depends on the amplitude of the 

 tide and the phasing of the tide with the storm- induced surge. When 

 maximum storm surge at the coast coincides with a maximum tide, the 

 highest water level will be produced at the shore. The water level 

 will be reduced when a low tide occurs simultaneously with the maximum 

 surge. The vertical departure of the water surface from its mean 

 position for any particular location because of tides depends on geo- 

 graphical location, basin configuration, and the magnitude of the tidal 

 forces at a particular time. The tide range can be as great as 18.2 feet 

 at Eastport, Maine, while only 1.3 feet at Key West, Florida. Generally, 



