coastal structure
DESCRIPTION
An overview of Coastal StructuresTRANSCRIPT
![Page 1: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/1.jpg)
Coastal structures
Prepared by
Ahmmed Zulfiqar Rahaman
![Page 2: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/2.jpg)
Coastal structures
Coastal structures can be anything human-made in the coastal area. They are constructed principally to protect the coast line.
![Page 3: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/3.jpg)
Coastal structures
Water resources engineers build these structures to:
slow down or prevent coastal erosion (for example, groins and sea walls)
increase access or mooring sites (for example, marinas, bridges, causeways and boat ramps)
support coastal subdivisions (for example, power poles and storm water pipes)
![Page 4: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/4.jpg)
What will happen if erosion occurs in this structure?
Lets see……
![Page 5: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/5.jpg)
cliff
![Page 6: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/6.jpg)
crack
![Page 7: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/7.jpg)
crack
![Page 8: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/8.jpg)
cave
![Page 9: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/9.jpg)
arch
![Page 10: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/10.jpg)
pillar
![Page 11: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/11.jpg)
stack
![Page 12: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/12.jpg)
stump
![Page 13: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/13.jpg)
reef
![Page 14: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/14.jpg)
coastal retreat
![Page 15: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/15.jpg)
To escape from such kind of erosion by wave action coastal structures are needed indeed……
![Page 16: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/16.jpg)
More than 70 percent of all coastal structures are on the shoreline for protection from probable damage by storm surge or coastal erosion called Shoreline protection
![Page 17: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/17.jpg)
Coastal structures
On the basis of purposes
there are different types of Coastal structures.
They are-
Revetments
Bulkheads & sea walls
Breakwaters
Groins & jetties
Coastal bridges & piers
Dikes & levees.
![Page 18: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/18.jpg)
Coastal structures Revetments:
Revetments are shoreline structures constructed parallel to the shoreline.
Revetments are structures placed on banks or cliffs in such a way as to absorb the energy of incoming water or explosives caused by water waves & current.
Fourth Cliff -Scituate, MA
![Page 19: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/19.jpg)
Coastal structures
Revetments: A cheaper alternative to sea walls is the revetment Usually built for shore protection
Point Allerton -Hull, MA
![Page 20: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/20.jpg)
Revetments: Modern revetments have concrete or shaped blocks of rip rap stone laid on top of a layer of finer material. Riprap has the advantage of good permeability plus it looks more natural.
Fourth Cliff -Scituate
![Page 21: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/21.jpg)
Coastal structures
Revetments components:
Armor layer: using armor stone(high wave energy environments) or rip-rap stone(lower wave energy environments)
Filter layer: using smaller stone & geo textile fabrics to act as a filter & under layer, which support the armor layer
Toe protection prevents under cutting & provides support for all about layer materials.
![Page 22: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/22.jpg)
Coastal structures Bulkheads: Bulkheads are vertical retaining walls to hold or prevent the soil from sliding seaward
Timber Bulkhead -Green Harbor Entrance Channel Marshfield
![Page 23: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/23.jpg)
Coastal structures
Timber Bulkhead -Green Harbor Entrance Channel Marshfield
Bulkheads reduce land erosion…..
![Page 24: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/24.jpg)
Coastal structures
Timber Bulkhead -Green Harbor Entrance Channel Marshfield
secondary purpose is to protect upland areas against damage from wave action.
Bulkheads……
![Page 25: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/25.jpg)
Coastal structures
Sea walls: form of hard and strong coastal defense constructed on the inland part of a coast to reduce the effects of strong waves separate the land & water.
Maumeebay (seawall)
![Page 26: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/26.jpg)
Coastal structures
Great Brewster Island Boston Harbor Islands
Granite Block Seawall
![Page 27: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/27.jpg)
Coastal structures
Curved or stepped sea walls are designed to enable wave to break and to dissipate wave energy and repel waves back to the sea.
Concrete Seawall Lynn Shore Reservation Lynn
![Page 28: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/28.jpg)
Coastal structures
- seawalls are vertical structures constructed parallel along the shore line.
- should last 20-30 years.
Seawall near Siwash rock in stanely park
Sea walls:
![Page 29: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/29.jpg)
Coastal structures
Breakwaters: breakwaters are large scale structures constructed seaward of, & usually to the shore line they attempt to break incoming waves before they reach the shoreline or the facility (e.g. marina) they are protecting .
![Page 30: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/30.jpg)
Coastal structures
Single breakwaters :
Single breakwaters may be attached or detached , depending on what they are being designed to protect
![Page 31: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/31.jpg)
Coastal structures
Single breakwaters :
a single detached breakwaters may protect a small section of shoreline
a single attached breakwater may a long structure to shelter marines & harbors from wave action.
![Page 32: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/32.jpg)
Coastal structures
Breakwaters…….
![Page 33: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/33.jpg)
Coastal structures
Head land breakwaters(HB): -a series of breakwaters constructed in an “attached” fashion to the shoreline & angled in the direction of predominant waves
-the shoreline behind the structures evolves into a natural “crenulate” or log spiral embayment.
![Page 34: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/34.jpg)
Coastal structures
Detached breakwaters:
detached breakwaters are constructed away from the shoreline, usually a slight distance offshore
they are designed to promote beach deposition on their leeside.
![Page 35: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/35.jpg)
Groins: groins are the oldest and most common shore-connected, beach stabilization structure they help to create or widen beaches by capturing sand moving along the shoreline.
Mortared Stone Groin “The Five Sisters”Broad Sound
Winthrop
![Page 36: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/36.jpg)
A groin is an active structure extending from shore into sea, most often perpendicularly or slightly obliquely to the shoreline
![Page 37: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/37.jpg)
Coastal structures
Types of Groins:
normal or straight
inclined or angled
submerged
Permeable
single
groin system or field
T L or Y shaped
Rubble-mound and sand-filled bag
attracting, deflecting or repelling
![Page 39: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/39.jpg)
Coastal structures
Characteristic of Groins:
they are usually made of tropical hardwoods which are more resistant to marine borers and erosion.
a few are made of concrete, steel or in more recent times large rocks.
they are spaced about 50-100 metres apart.
may have a life of 15-20 years
![Page 40: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/40.jpg)
Coastal structures
Concrete groins…….
Ukraine ( the black sea)
![Page 41: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/41.jpg)
Coastal structures
Shoreline response to groins
![Page 42: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/42.jpg)
Coastal structures
Jetties and piers a structure extended into a sea, lake, or river to influence the current or tide or to protect a harbor a protecting frame of a pier a landing wharf
Timber Pier -George’s Island Boston Harbor Islands
![Page 43: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/43.jpg)
Jetties & piers……..
Tybee
![Page 44: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/44.jpg)
Jetties are shore-normal stone structures commonly used for training navigation channels & stabilizing inlets
![Page 45: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/45.jpg)
Coastal structures
Characteristics of jetties: they prevent intrusion of long-shore sediment transport they cause higher flow velocities that scour the channel to a depth required for safe navigation.
![Page 46: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/46.jpg)
Coastal structures
Coastal bridges and piers
Biloxi bridge
![Page 47: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/47.jpg)
Coastal structures
Coastal bridges and piers
Cuba bridge
![Page 48: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/48.jpg)
Coastal structures
Dikes & levees
dikes are typically earth structures
they keep elevated water levels from flooding interior lowlands.
sometimes they refer to as dam
![Page 49: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/49.jpg)
Coastal structures
Dikes & levees
Levees…..
![Page 50: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/50.jpg)
Coastal structures
Gabion
Emergency shore protection:
for emergency shore protection gabions are used. gabion is a metal cage filled with rocks, about 1 metre by 1 metre square
![Page 51: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/51.jpg)
Coastal structures
Gabion:
![Page 52: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/52.jpg)
Coastal structures
Gabion:
they are stacked to form a simple wall.
used to protect a cliff or area in the short term only
gabions have the advantage of ease of use and are
relatively cheap but their life span is short.
![Page 53: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/53.jpg)
Coastal structures
Now-a-days X-block & Tripodal blocks are vastly used for building such coastal structures.
![Page 54: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/54.jpg)
Coastal structures
Tripodal block……
![Page 55: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/55.jpg)
Coastal structures
Coastal structures in Bangladesh
Bangladesh has 710 km long coastline
![Page 56: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/56.jpg)
Coastal structures
Natural calamities or storm surge visit our country every year So to protect our coastline from wave action or coastal erosion, coastal structures are obviously needed
Sonadia dip
![Page 57: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/57.jpg)
Coastal structures
Coastal structures in Bangladesh
The coastal region of Bangladesh has 123 embanked polders, constructed in late sixties to protect the land
![Page 58: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/58.jpg)
Coastal structures
St. Martin island jetty…..
Kutubdia
![Page 59: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/59.jpg)
Coastal structures Importance of coastal structures
Coastal structures are important assets for the economic health of many coastal communities to: Protect harbors and inlets that are important commercial and military navigation links Protect shore-based infrastructure Provide beach and shoreline stability control Stabilize navigation channels Protect navigation, coastal communities, roadways, bridges, etc. Provide flood protection Provide recreational activities
![Page 60: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/60.jpg)
Why should we let such coastal area disappear…….???
![Page 61: Coastal structure](https://reader033.vdocuments.site/reader033/viewer/2022052619/555b4f7dd8b42a16758b4f83/html5/thumbnails/61.jpg)
Coastal structures
Summary
Coastal structures influence waves currents sediment transport in the near shore environment
A systematic approach is needed in order to minimize negative effects