Shoreline Features Bulkheads Vertical concrete metal or wood
Shoreline Features
Bulkheads Vertical concrete, metal, or wood walls Allows upland to be used up to the waters edge Stop the shoreline retreat Water turbulence can erode the seaward toe of the structure • Can cause rapid erosion at the end of the structure • •
Bulkheads
Breakwater • Rubble mounds of rock covered by concrete or stone • These are structures used to improve navigation in waterways • Reduces wave and current action on the landward side of the barrier • These structures can be very expensive
Breakwaters
Groins • Short piers extending from the beach spaced about 100 yards apart • Can be made of wood, stone, concrete, … • Helps retain the beach by preventing erosion • Sand accumulates on the upward drift side and excessive erosion can happen on the downward side • Rip currents can happen near these • They must cross public beaches and can give a beach a serrated shape
Groins
Seawalls • Rigid mass of concrete and steel built parallel to the shoreline • Designed to take the impact of large waves • Help reduce the effect of storm surge (hurricanes) and large damaging waves (tsunami) • They are very expensive to build
Seawalls
Riprap • • Coarse rubble placed along a shoreline Reduces erosion due to constant wave action Least expensive option for reducing erosion Very common on lakeshores and river edges to reduce erosion from boat wakes
Riprap
Dunes • Natural mounds of sand vegetation • Without dunes, beaches can’t absorb the action of large waves • Provide sand that helps replenish the beach • Human activity in the dunes reduces the vegetation needed to stabilize the dunes • Shape and size of the dunes are always changing
Dunes
Beach Nourishment • Adding sand to the beach where it has been excessively eroded • Engineering is needed to make this process work • The sand must be the correct type for the process to be effective
Artificial islands off of the coast of Dubai have had major erosion problems. Palm Islands “The World” Archipellago
Fabric • Artificial sea grass or other material • Designed to trap sand reduce erosion in the surf zone • Can be used as a backer behind walls to hold sand in place
Jetties • Long concrete or rock structures on both sides of an inlet or navigation channel • Jut out along navigation routes to control silt depositing into channels • Jetties can collect sand on the upward side and make erosion worse on the downward side
Jetties Port Aransas North Jetty St. Josephs Island Port Aransas Ship Channel Port Aransas South Jetty Mustang Island
Vegetation • Naturally occurring or planted species in the dunes or near shore in the water • Help keep sand from eroding due to wave or wind action and help stabilize the soil • Plant roots grow down into the soil and hold it in place
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