Final answer:
Seawalls are constructed behind beaches to guard against the impact of strong waves and surges, preserving the integrity of coastlines and nearby structures. They act as barriers between the sea and land, mitigating erosion and potential property damage, and are a vital part of coastal defense strategy.
Step-by-step explanation:
Seawalls are built behind a beach and serve to protect structures from strong waves and surges. Unlike breakwaters, jetties, or groins, seawalls are specifically designed to defend the shore from the direct attack of incoming waves and can be an integral part of coastal defense strategies. In the context of coastlines and harbors, seawalls serve as a form of coastal fortification that provides a barrier between the ocean and inland areas, helping to prevent coastal erosion and property damage.
These structures are often made of concrete or large boulders and should be well-engineered to withstand the force of the waves, especially during storm surges or high tide. In some cases, seawalls are complemented by other structures like wetlands, which can provide natural protection against storm surges and flooding. Whether for residential areas, cities, or harbors, seawalls play a crucial role in mitigating the impacts of waves and protecting valuable land from being lost to the sea.