0.001 





0.01 



0.001 



0.002 



0.01 



0.02 



0.1 



Figure 3-53. Predicted random wave (sea) setup on plane slopes for 

 d_ 

 H 



= 0.5 . 



Setdown in semienclosed basins (bays and estuaries) also may be sub- 

 stantial, but the fall in water level is influenced by the coupling to the 

 sea. Setdown produces some detrimental effects, such as making water-pumping 

 facilities inoperable due to exposure of the intake, increasing the pumping 

 heads of such facilities, and causing navigational hazards because of 

 decreased depths. 



However, rises in water level (setup rather than setdown) are of most 

 concern. Abnormal rises in water level in nearshore regions will not only 

 flood low-lying terrain, but provide a base on which high waves can attack the 

 upper part of a beach and penetrate farther inland. Flooding of this type 

 combined with the action of surface waves can cause severe damage to low-lying 

 land and backshore improvements. 



Wind-induced surge, accompanied by wave action, accounts for most of the 

 damage to coastal engineering works and beach areas. Displacement of stone 



3-109 



