causes problems for the people on the opposite, downcurrent side. Those people no longer
have sand reaching the areas in front of their homes. What happens as a result is that people
must build another groin to trap sand there. This means lots of people build groins, but it
is not a very good answer to the problem of wave erosion.
Figure 10.22: Groins are built perpendicular to the shoreline to help keep sand from moving
off the beach. ( 54 )
Someotherstructuresthatpeoplebuildincludebreakwatersandseawalls(Figure10.23).
Both of these are built parallel to the shoreline. A breakwater is built out away from the
shore in the water while a sea wall is built right along the shore. Breakwaters are built in
bay areas to help keep boats safe from the energy of breaking waves. Sometimes enough
sand deposits in these quiet water areas that people then need to work to remove the sand.
Seawalls are built to protect beach houses from waves during severe storms. If the waves
in a storm are very large, sometimes they erode away the whole sea wall, leaving the area
unprotected entirely. People do not always want to choose safe building practices, and
instead choose to build a beach house right on the beach. If you want your beach house to
stay in good shape for many years, it is smarter to build your house away from the shore.
Lesson Summary
- Waves in the ocean are what we see as energy travels through the water.
- The energy of waves produces erosional formations like cliffs, wave cut platforms, sea
arches and sea stacks. - When waves reach the shore, deposits like beaches, spits and barrier islands form in
certain areas. - Groins, jetties, breakwaters and seawalls are structures humans build to protect the
shore from the erosion of breaking waves.