BrigantineNOW Reader Feedback from ‘John’. Things that need to be considered when talking “beach jetties”.
Erosion is a natural part of the cycle of the beach. The natural flow of water deposits sand at times and then removes it at other times. During the cycle the beach may have a great deal of sand or very little, but over time it balances out. Humans desire to eliminate the part of the cycle with erosion control. Jetties interrupt the natural flow of water and sand in an attempt to control erosion with corresponding effects.
One effect from the erection of jetties for erosion control is the accumulation of sand and sediment behind the jetty. The jetty prevents the natural flow of water and the sand and sediment that are carried with the flow cannot get past the structure. This accumulation reverses erosion and provides extra sand for the beaches behind the jetty. This accumulation creates unintended consequences for other beaches.
While jetties accumulate sand on the up drift side, the opposite effect occurs on the down drift side. The jetty causes erosion due to the lack of sand which is caught on the other side. The solution is to erect another jetty, but the process never ends. Eventually there will be a last jetty and the beach and land on its down drift side will suffer the consequences of erosion. Jetties built to control erosion end up causing it. This effect is the reason for jetties no longer being a preferred method of erosion control.