What is the reason for building a jetty?

Question

1)it provides a place for people to fish from the beach safely
2)it blocks dangerous flood tides from entering the estuary
3)it blocks the longshore current from building sandbars that could block the pass
4)it provides a place for boats to dock
5)it restores the eroded sediment on the beach

Answer 1

A jetty is primarily built for the following reasons:

1. It provides a place for people to fish from the beach safely - While jetties may offer some fishing opportunities, this is not their primary purpose.

2. It blocks dangerous flood tides from entering the estuary - Jetties can play a role in managing tidal flows, but their main function isn't solely about blocking flood tides.

3. It blocks the longshore current from building sandbars that could block the pass - This is a significant reason for building jetties, as they help maintain navigable channels by disrupting currents that would otherwise deposit sediment.

4. It provides a place for boats to dock - While jetties can support docking in some contexts, they are not primarily structures for docking boats; that function is more associated with docks or piers.

5. It restores the eroded sediment on the beach - Jetties do not restore sediment on beaches in the way that other structures (like groins) do. They can alter sediment distribution but do not directly restore it.

Given these points, the most accurate primary functions of a jetty are 3) to block longshore currents and maintain navigable passes, and 4) in some contexts, to provide a docking area. However, the main intent of most jetties is related to their effects on navigation and sediment management, primarily aligning with reason 3.