What defines a coastal flood?

A coastal flood is defined as an event where the coast is inundated due to natural conditions. This definition encompasses the various phenomena that can result in flooding at coastal areas, such as storm surges associated with hurricanes, high tides exacerbated by weather patterns, or tsunamis. The key element here is the inundation of coastal land, which is a direct consequence of natural factors like ocean currents, wind conditions, and geological changes.

Other choices focus on specific conditions that might lead to flooding but do not accurately capture the broader context of what constitutes a coastal flood. For example, while excessive rainfall causing riverbanks to overflow might lead to flooding in adjacent areas, it does not strictly define flooding occurring at the coast specifically. High tides that happen without any storm conditions are part of the natural tidal cycle and do not inherently cause flooding in coastal zones unless combined with other factors. Lastly, a sudden drop in sea levels along the coast is not a flooding condition but rather a rare event that might suggest an unusual environmental change, which would not typically be characterized as flooding of the coast.