Beach Erosion

Wave refraction Most waves do not come straight into shore. Usually the wave crest arrives at an angle to the shoreline. The wave will then bend to become parallel to the shoreline. Wave refraction

Longshore Current A water current that develops parallel to the coastline This current is why it is impossible to stay in front of the lifeguard stand, you keep getting pushed down the beach The water pushes you into the shore at an angle and pulls you straight back

LONGSHORE DRIFT Sediment that is moved parallel to the shore by longshore currents.

Rip Current Narrow Currents that form perpendicular to the shore line. Where water is able to flow quickly back into the ocean. To escape a rip current, swim parallel to the shore.

Sand Spit A fingerlike ridge of sediment that extends into open water Example – Sandy Hook

Sand Dunes Why are sand dunes important? Water Quality - sand dune vegetation acts as a filter maintaining coastal water quality. Coastal Protection - dunes act as a buffer and prevent beach erosion - more effective than jetties or seawalls Cultural value - they enhance natural landscape and provide habitat for fauna & flora.

KEEP OFF THE DUNES Dunes are mother nature’s protections against storms. The vegetation planted on the dunes such as dune grass enable the roots to hold the dunes in place during a storm. Walking on the dunes damages the grass, and causes more beach erosion.

Human SOLUTIONS Humans have built houses all along the shoreline, in some cases destroying the sand dunes for a better view of the ocean. Because these natural protections are gone, we have built structures along our beaches to prevent beach erosion. All of these structures need maintenance and replacement to counter the never ending assault of the ocean.

Groins Short walls that are built perpendicular to shore in order to trap moving sand and widen a beach.

The Problem: Sand gets trapped on one side of the groin, while erosion is enhanced on the opposite side. OCNJ

Rock walls designed to protect an entrance to a harbor from sediment deposition and storm waves. Jetties

The Problem: Sand gets trapped on one side of the jetty, while erosion is enhanced on the opposite side, robbing the beaches of sand on one side. Example: The Cape May inlet is causing the Wildwood beaches to the north to grow , and Cape May beaches to the south to shrink.

CAPE MAY INLET CAPE MAY WILDWOOD

Off shore structures built parallel to the shoreline to absorb the force of large breaking waves and provide quiet water for boats near shore. Breakwater

The Problem: The break water prevents longshore drift, which causes a build up of sand in front of it, often causing the harbor to fill in with sand. This can cause a loss of beaches downdrift of the breakwater.

Break waters can often be found in front of a Jetty

Seawall - a wall built to prevent beach erosion especially during storms.

The Problem: Seawalls are very expensive to install and are often breached during storms. The Seawall can actually cause more wave action, increasing erosion in the area and reduce the amount of sediment is available for surrounding beaches.

Sea wall installation in Mantoloking

Beach Replenishment Using a dredge and pumps to bring sand from offshore to replace sand that was washed away from storms. A VERY temporary solution - needs to be completed every few years and can be washed away from ONE storm. NJ has spent 1 billion dollars on beach replenishment in the past 30 years!!!

WHAT’S YOUR OPINION With the global sea level rising, should the government keep putting money into the above prevention measures?