the greater will be the rise of water at the coast. The forward speed, 

 however, can be an important factor in the total rise. If there is a 

 gradual pressure change, the water level will rise in regions of low 

 pressure and fall in regions of high pressure, thus the pressure is one 

 of the important components of the surge. The size of the storm relative 

 to the size of the basin is also an important factor, since a storm too 

 large for the basin could limit the hurricane's growth as well as in- 

 tensity because of the interference of the outskirt winds with the land. 

 An example of a very large storm relative to the basin size was Hurricane 

 Carla (1961) which made landfall near Port O'Connor, Texas. When this 

 storm was approximately centered in the western end of the Gulf of Mexico 

 basin, its winds at the edge were sweeping the coastal terrain of the 

 east Coast of Mexico as well as the Coasts of Texas and Louisiana. 



Rainfall associated with the hurricane can contribute to the rise 

 of surge on the open coast because of the volume added to the system; 

 however, since the sea basin is such a large reservoir, the rise caused 

 by precipitation is generally neglected. For semi enclosed bays and 

 estuaries, rainfall can be an extremely important factor in estimating 

 the surge for any location within the system. In fact, in a semienclosed 

 basin, the peak surge height may be increased as much as 3 feet due to 

 direct rainfall on the water surface when coupled with the surface rain- 

 fall runoff from the watersheds located adjacent to the basin. Although 

 the direct effect of rainfall on the open sea can be usually neglected 

 in estimating the maximum storm surge along the open coast, streams dis- 

 charging large quantities of water in the sea may affect the maximum 

 water level locally. 



When wind-generated surface waves of a hurricane move into the near- 

 shore regions and break on the sloping beach more or less parallel to the 

 depth contours, they may be responsible for a significant water transport 

 shoreward. As the water moves back seaward by gravity, the momentum of 

 the water particles is substantially decreased, resulting in a water sur- 

 face gradient extending from the breaker region to the shore. Thus, the 

 kinetic energy of the particles is increased as the wave breaks and moves 

 shoreward, and decreases when the particles move back seaward. Part of 

 the kinetic energy is transformed to potential energy and some energy 

 is lost in the form of friction and turbulence. However, the gain in 

 potential energy results in an increased water level at the shore. Wave 

 setup is the superelevation of the water surface over normal surge ele- 

 vation due to onshore mass transport of the water by wave action alone 

 (Saville, 1962). 



Model studies of wave setup have been made by Fairchild (1958) and 

 Saville (1962); theoretical studies of wave setup were made by Dorrestein 

 (1962), Fortak (1962) and Longuet-Higgins and Stewart (1962, 1963, 1964). 

 All of these studies show that the water level is depressed below the 

 Stillwater level (SWL) at the point of maximum wave amplitude or where 

 the wave peaks up and breaks. Saville (1962) indicates that waves break- 

 ing on a beach face, with the crests parallel to the depth contours, 

 produce a wave setup at the shore of about 10 to 15 percent of the 



