Coastal Processes with Engineering ApplicationsBy R.G.Dean & R.A.DalrymplePart One Chapter 1: OverviewIntroduction to coastal processesYinghao LIRinko 2010/12/16

Table of contentsIntroductionConceptions and descriptive termsTransport processHuman impact by coastal engineering projectsPerspective of coastal engineering

IntroductionCoastlines:Limit of land and seaUnique in terms of composition and physical processesSimilar nature and behavior around the worldCoastline between Tenby & Monkstone Point, G.B.

Conceptions and descriptive termsBeaches around the world are similar in composition and shape.Beach profile terminology

Conceptions and descriptive termsBarrier island & Bayhead barrier

Narrow strips of sand that parallel to the mainland.From a few kilometers to more than 100 km.Morphology depend on tidal range, wave energy, sediment supply, sea-level trends and basement controls.Large concentration in North America, not many in Japan.Tidal inletBarrier island in the Gulf of MexicoPoint Dume

Conceptions and descriptive termsTidal inlets Provide a means of ocean/lagoon water flow Capture sand along the coast Size & shape are the result of a balance of sand Ebb tidal shoal & Flood Tidal shoal

Hog Inlet, South Carolina

Conceptions and descriptive termsSplitA deposit landform connected to land and extend into the sea

Formation of spitSidney Spit, Canada

Transport processesEnergy origine: The WaveMobilization and suspension of the sedimentsCreation of nearshore currents

Along the shorelineCross-shorelineTransportLittoral drift [m3/y]Currents

Transport processesLongshore transport (or littroal transport):Dominant direction, downdrift, undrift Cross-shore transport:- Movement to the shore- Important to beach erosion- Responsible for the existence of profile changes

The separation of the total transport into components parallel and perpendicular to the shore is artificial.

Human impact by coastal engineering projectsLong history of shoreline transformation: Ports, habors, etc.Recent coastal developmentTable1: Coastal population within 100km of coast

CountryNumber (million)ProportionU.S.31043%Europe31443%China30624%Japan12296.3%

Human impact by coastal engineering projectsEngineering works interfer with sediment transport processes

Ports, navigational channels and jetties, dams, sand mining, groundwater extractionsBeach erosion Accumulations of sand

Human impact by coastal engineering projectsBeach NourishmentPlacement of large quantities of sand on an eroding beach to advance the shoreline seaward of its present locationCommon methods for erosion mitigationBeach nourishment plan view and profile (Dean and Abramian, 1993)

Human impact by coastal engineering projectsOffshore breakwatersA shore-parallel structure composed of rocks and is designed to reduce the wave energy shoreward of the structureCan be emergent or submergedMore than 3000 in Japan www.rivaphotos.comWave sheltering & DiffractionDowndrift erosion

Human impact by coastal engineering projectsCoastal armoringEffects on adjacent beaches and offshore profile not well understoodConcern over sea level rise and shoreline erosionCrux of the debate: value of the upland and potential life losses during stormswww.spur.org

Perspective of coastal engineeringCoastline alteration is globalPressure on coastline caused by population growing is inevitable

Perspective of coastal engineeringObjective: understanding coastal processes and developing strategies to fight against shoreline erosion

Current difficulties: mathematical and statistical equations are not fully known difficulty to make modelsUnderstanding of coastal processes requires:Analytical capabilityInterest in the workings of natureAbility to interpret complex pieces of evidencesExperience from studying and working with coastal projects

Thank you for your attention

The sand making up this profile is shaped by waves coming from the offshore and breaking in the near shore zone. Thedry beach may have one or more berms, which are horizontal sections of the profile,

The beach profile and planform shapes discussed in the preceding section are a resultof the action of waves and currents at the shoreline. The waves not only suspendthe sediments but give rise to nearshore currents that carry the suspended sedimentalongshore or cross-shore