pure geog coasts notes!

coasts gateway1 factorsaffectingwaveenergy: - windspeed;fasterwind,greaterwaveenergy- windduration;longerwindblows,largerwaves- fetch;greaterfetch,greaterwaveenergy howwavesaffectcoastalareas: - swash;whenwavesbreakonacoast,carriessedimentswithit(breakscosoffrictionandgravitywithland)- backwash;carriessedimentsfromcoasttosea - constructivewaves;breakfarfromshorewithlittleenergy.depositssediments,notalotoferosion,, andformsgentleslopes(strongswash,weakbackwash)- destructivewaves:breaksviolentlyontheshorewithhighenergy.removessediments(erodefinersediments)andleavesonlycoarsesediments,causingsteepgradient.(weakswash,strongbackwash) + theircharacteristics- constructivewaves:lowgradient,smallwavesandlowwaveheight,longwavelength,6-8permin,swashmorepowerfulthanbackwash- destructivewaves:steepgradient,largewavesandwaveheight,shortwavelength,10-14permin,backwashmorepowerfulthanswash waverefraction: 1. wavesapproachheadlands,divergetobays.2. sincemorewaveenergyatheadlands,moreerosionoccur,splitstobaysbutlessererosion coastalprocesses: - erosion- hydraulicaction=wavesstrikecliff,trapsairinrockjointsandcompressed,puttingpressureonthejoints.jointsweakenedandeventuallyshatters

- abrasion=wavesbreakatcliff,sedimentsmeanttobedepositedarehurledagainstthecoast,scrapesandloosencliffs.eventuallyundercutsthecliff- attrition=rockparticlescarriedbywavesbreakdownintosmallerpiecesandbecomesmootherandmoreroundedovertime(class5!)- solution=seawaterchemicalrxnwithwater-solmineralsincoastalrocks.rocksareweakenedandeventuallydisintegrate sedimentmovement/transport: - beachdrift=sedimentsmoveupthebeachatanangleasswashandperpendiculardownthebeachasbackwash(zig-zagmovement)- longshoredrift=longshorecurrents(currentsthatflowparalleltoacoast)generated,movingsedimentsalongtheshore.- longshorecurrents+beachdrift=longshoredrift sedimentdeposition: - sedimentserodedfromcoastsaretransportedawayanddepositedelsewhere.aswaveenergydecreased,wavesareunabletocarrysedimentsanddepositslargesediments→smallsediments,resultinginavarietyofbeaches- locationofcoasts:- coastsshelteredfromstrongwinds=lessdestructivewaves- deepbaysshelteredbyheadlands=sandybeaches cliffs - hydraulicaction/abrasionerodescrack/jointontherocksurface,enlargingtoformanotch- furtherdeepenedtobecomeacave- moreerosion=roofofthecavecollapses,formingasteepcliff headlands+bays(johor,msia) - lessresistantrocks=bayerodedfasterthan- moreresistantrocks=headlands

caves→arch→stack - partsofheadlandswithlessresistantrockcanbeeasilyeroded(hydraulicactionandabrasion),formsacave- cavesmaydeveloponbothsidesoftheheadland,andfurthererosionmayeventuallyjoincavestgtandcreatinganarch(bridgeofrock)- furtheron,theroofofthearchcancollapsetoformastack beaches - azoneofsedimentdeposition;loosesand,gravel,pebbles,brokenshells,corals- usuallycomefromerodedcliffs,riverdepositsandsedimentscarriedbywaves. spitsandtombolos - spit:along,narrowridgeofsedimentswithoneendattachedtoamainland,formedbylongshoredrift.- whenthereisanabruptbendinthecoastline,longshoredriftwillcontinuetotransportsedimentsintheoriginaldirectionforsomedistance.moresedimentsaredepositedafterthebendofthecoastlineandaccumulates,formingahook/curveattheendofthespit - tombolo:aspitconnectedtothemainlandthatcontinuestoextenduntilitconnectstoanoffshoreisland/anotherexistingisland gateway2 usageofcoastalareas: - fisheriesandaquaculture(camau,viet)- fisheriesareareaswherefisharebredandraised- farmingfishnearcoasts=aquaculture:P- supplies⅓oftheworld’sfishsupply- example(camau):producesthemostshrimp🦐 ,productionreachedhighestofUSD800millionin2010! - housingandtransportation(kukup,msia)

- stilthouses!connectedwithwalkways,allowingpeopletomovearoundthecommunityeasily- boatsarealsoaformoftransportation- kukup:aplaceofstilthouses.somefloatingfishfarms(andtheysellfreshfish=money),scheduledferryservices(alsomoney) - tourismandrecreation(sentosa,sg)- one°15marinaclub,worldclassmarinafacilities- offersmaintainingservicesforboatsandyachts,recreationalboatingfacilities- alsogothotel,museum,andmarinelifepark,,largeamountofvisitors coralreefecosystems - developslightlybelow/atsealevelontheseabed,madeupofcoralpolypsanimals)- usuallydistributedbetweentropicofcancerandtropicofcapricorn:)[exception:japan][southeastasiahighestbiodiversityandlargestareaofcoralreefs] conditionsforgrowth - salinity=34-37parts/1000coralreefs- watermovementforoxygen!!- NOSEDIMENTS:(cansuffocatecorals- seasurfacetempnotlowerthan17-18c- clearwaterforsunlight;photosynthesis!!lowturbidity valueofthem - supports>25%oftheearth’smarinefishspecies- smallerfishgrazeonthecoralpolyps,largerfishwilleatthesmallerfish- absorbwaveenergy,lesseningerosion- tropicalcyclonemaybreakthemduetohighpressure - threatsofcoralreefs:

- overcollection-weakensanddisruptscoralecosystem,morevulnerabletothreats(ph)- fishingmethods-- spearfishing→selectivedepletionoffishpopulationdisruptsecosystem’sfoodchain(netherlands)- dynamiteblasting→destroycoralreefhabitat(ph/indo)- recreationaluseofcoasts-tourismactivities:expansionofcoastalresorts,anchoringofboats→wastedisposedintowater+oilspillsfrmboats,,anchorsdamagecorals(srilanka)- coastaldevelopment-expansionofcoastalresorts- reclamation/expansionofland=dumpingrocksandsandontoreefs→coralreefsaresuffocatedanddestroyed- expansionofcoastalresorts→morewastedepositedintosea=coralreefsaresuffocatedanddestroyed- climatechange→coralbleachingduetorapidchangesinseatemperatures+sealevels,coralscannotadaptasfast mangroveecosystems:- salt-toleranttropical/subtropicalplantsthatgrowinconditionsthatotherplantsareunabletoadaptto(tidalmud,uniqueplantsandanimals,mostproductiveandbiologicallycomplexecosystems valueofmangroves:- stabiliseshorelines- absorbwaveenergy- allowssedimentstobuildupontheirroots=lessenerosion- abreedinggroundandhabitatforaslotofmarinecreatures(anchoringontherootsofthemangroves threatsonmangroves - clearingmangroves→fuelandcharcoal,moreinLDCs=fishbreedinggroundslessened+coastsmoreopentostormwaves(indo)- conversionoflandforotheruses→becomepaddyfields/shrimpfarms=mangrovesarecleared,,morevulnerablecoasts(viet/thai)- coastaldevelopment-landisreclaimedforhousing,industryandrecreationaluses=largeclearanceofmangrovesfrmenvironment,,morepollutioninwatersduetohumanactivities(caribbean)- climatechange-increasedsealevels,,extremestormactivity=mangroveshavemoretroublecolonisinginlandareasbcincompetitionwithhumanactivities(farming,seadefences)(thai)

gateway3 howtomanagecoastalareas?- lawsandregulations- coastalprotectionmeasures lawsandregulations - limitingdamagingactivities- activitiessuchas:blastingcoralreefsforboatstotravelefficiently,clearingmangrovestodevelopfishfarms,dumpingwasteintocoastalareas/seas,constructingfacilitiesthatreplacethenaturalfeaturesofthecoast(marinas,docks)- limiting≠banning(canbeinefficientandcostly)- eg:portphilip:sandduneswerebeingtrampledonbypeople,,dunevegetationdestroyedmakingsanddunesexposedtowinderosion- pros:authoritiesfencedoffdunesbuiltaccesspathstothebeachandallowedthecoastalenvironmenttorecover- cons:notaestheticallypleasing+somepartsofthebeachwereblocked - protectingcoastalresources- topreventresourcesfrombeingdepleted/exploited(eg:fish,maybevulnerabletooverfishing)- ^^especiallyincoralreefareasinSEAwherethere'salotofblastingandpoisonfishing- eg:wakatobinationalpark(indo)→markedoffzonestopreventcommercialfishing,throughlocalmanagement/establishmentofanaturereserve.(marinereserve)- pros:protectsmarineecosystems,allowingfishandendangeredspeciestobreedandthrive:)- cons:opposedbylocals(fishermen)-accesstoamajorfood/moneysupplybeingdenied,,valuableresource. - restrictdevelopmentinareaspronetonaturalhazards- govtandauthoritiesresearchonhowsevere/widespreadtheproblemis,planforit,andthenmake+enforcelaws.- usuallyinvolvesacombinationofRAD:- Retreating=relocationofcertainstructuresawayfromhazard-proneareas- usa:fedemergencymanagementagencysteersdevelopmentawayfrmareaspronetocoastalerosion/flooding- Avoidance=regulatingcoastaldevelopment

- indo:restrictfarmsandresidencesfrombeingestablishedolow-lyin