For the more information about the geologic resources of the
National Park Service, please visit
http://www.nature.nps.gov/geology/. Hard structures are often
placed in coastal environments to counteract erosion in
sediment-deficient areas, or to deter accretion in dynamic areas
such as inlets. Hard engineering includes breakwaters, seawalls,
revetments, jetties, and groins. Unfortunately, these
anthropogenic modifications usually increase erosion in
downdrift areas, increasing the necessity for additional
shoreline stabilization efforts. The creation of new hard
structures is currently banned in many states, or strongly
discouraged in coastal management practices. Groins are shore
perpendicular structures, used to maintain updrift beaches or to
restrict longshore sediment transport. Jetties are another type
of shore perpendicular structure and are placed adjacent to
tidal inlets to control inlet migration and minimize sediment
deposition within the inlet. Shore parallel structures
(seawalls, bulkheads and re