Tidal floods are overflows of coastal lands bordering an ocean, an estuary, or a lake. These coastal lands, such as bars, spits and deltas affected by the coastal current, occupy the same protective position relative to the sea that flood plains do to rivers. Coastal flooding is primarily due to landward flows caused by high tides, waves from high winds, surges from distant storms, tsunamis, or a combination of these events. Along shores, damage also can be caused by ice driven ashore by wind or wave action. Tidal floods can also be caused by the combination of waves generated by hurricane winds and flood runoff resulting from the heavy rains that accompany hurricanes. Tidal floods may extend over large distances along a coastline. The duration of tidal floods is usually short, being dependent upon the elevation of the tide which rises and falls twice daily in most places. However, maximum tide elevations can be identical on consecutive days. In the case of tidal floods associated with hurricanes, the high velocities of hurricanes winds often produce wave heights about 3 feet higher than the maximum level of the prevailing high tide.
Most of the severe tidal floods are caused by tidal waves generated by high winds superimposed on the regular cyclic tides. Tropical hurricanes are the primary sources of the extreme winds. Each year, several hurricanes enter the USA mainland, striking along the coasts of the Gulf of Mexico and the Atlantic Ocean.