Final answer:
The National Flood Insurance Program may offer limited coverage for wharves, piers, and docks, depending on their use. Flood risks can change and there is certainly a possibility of a similar flood event occurring within the next 20 years. Wave action against boats can be mitigated by coastal structures like water breaks with the right design and orientation.
Step-by-step explanation:
The National Flood Insurance Program (NFIP) is a program created by the Congress of the United States in 1968 to mitigate future flood losses nationwide through the adoption of and enforcement of floodplain management standards. While coverage under the NFIP generally includes buildings and their contents, there are specific guidelines regarding structures such as wharves, piers, and docks. These types of structures may have limited coverage under the NFIP, especially when they are not part of the residential property but are instead commercial or used for income generation.
It is also important to note that flood risks are not static and can change over time. For example, a flood with a similar discharge to that of the event from 9/23/2009 can indeed happen again in the next 20 years. The possibility of such natural events typically depends on a range of factors including climate conditions, changes in land use, and the implementation of floodplain management measures.
Concerning wave action and protection provided by coastal structures, it is known that coastlines can be naturally shielded from waves due to their orientation or geographic features that limit exposure to open waters. For instance, a water break with a 50.0-m-wide opening designed to guard a harbor can significantly alter the impact of waves with a given wavelength, such as 20.0-meter waves, on the boats within the harbor. The angles at which boats are most protected can be calculated by applying principles of wave diffraction and interference.