Editing Surfing (section)

=== Jetties and their impacts on wave formation in the surf zone ===
{{expert needed|1=Limnology and Oceanography|reason=Contents of this section are incomprehensible. Source is paywalled |date=February 2021}} 
[[Jetty|Jetties]] are added to bodies of water to regulate erosion, preserve navigation channels, and make harbors. Jetties are classified into four different types and have two main controlling variables: the type of delta{{clarify|What is the delta in this context?|date=February 2021}} and the size of the jetty.<ref name=Scarfe2003>{{cite journal |last1= Scarfe |first1=B.E. |author2=M.H.S. Elwany, K.P. Black, and S.T. Mead |title=Categorizing the Types of Surfing Breaks around Jetty Structures |url=http://escholarship.org/uc/item/09f405bq |journal=Scripps Institution of Oceanography Technical Report |date=7 March 2003 |pages=1–8}}</ref>

==== Type 1 jetty ====
The first classification is a type 1 jetty. This type of jetty is significantly longer than the surf zone width and the waves break at the shore end of the jetty. The effect of a Type 1 jetty is sediment accumulation in a wedge formation on the jetty. These waves are large and increase in size as they pass over the sediment wedge formation. An example of a Type 1 jetty is Mission Beach, San Diego, California. This 1000-meter jetty was installed in 1950 at the mouth of Mission Bay. The surf waves happen north of the jetty, are longer waves, and are powerful. The bathymetry of the sea bottom in Mission Bay has a wedge shape formation that causes the waves to refract as they become closer to the jetty.<ref name=Scarfe2003 /> The waves converge constructively after they refract and increase the sizes of the waves.

==== Type 2 jetty ====
A type 2 jetty occurs in an ebb-tidal delta, a delta transitioning between high and low tide. This area has shallow water, refraction, and distinctive seabed shapes that create large wave heights.<ref name=Scarfe2003 />

An example of a type 2 jetty is called "The Poles" in Atlantic Beach, Florida. Atlantic Beach is known to have flat waves, with exceptions during major storms. However, "The Poles" has larger than normal waves due to a 500-meter jetty that was installed on the south side of St. Johns. This jetty was built to make a deep channel in the river. It formed a delta at "The Poles". This is a special area because the jetty increases wave size for surfing when comparing pre-conditions and post-conditions of the southern St. Johns River mouth area.<ref name=Scarfe2003 />

The wave size at "The Poles" depends on the direction of the incoming water. When easterly waters (from 55°) interact with the jetty, they create waves larger than southern waters (from 100°). When southern waves (from 100°) move toward "The Poles", one of the waves breaks north of the southern jetty and the other breaks south of the jetty. This does not allow for merging to make larger waves. Easterly waves, from 55°, converge north of the jetty and unite to make bigger waves.<ref name=Scarfe2003 />

==== Type 3 jetty ====
A type 3 jetty is in an ebb-tidal area with an unchanging seabed that has naturally created waves. Examples of a Type 3 jetty occurs in “Southside” Tamarack, Carlsbad, California.<ref name=Scarfe2003 />

==== Type 4 jetty ====
A type 4 jetty is one that no longer functions nor traps sediment. The waves are created from reefs in the surf zone. A type 4 jetty can be found in Tamarack, Carlsbad, California.<ref name=Scarfe2003 />