Introduction to Water Waves and Beach Erosion Dr. Tsutomu Sakakiyama JICA Senior Volunteer September, 2018 Author Dr. Tsutomu Sakakiyama is a Senior Volunteer of the Japan International Cooperation Agency (JICA) and advises the National Works Agency (NWA) in the field of coastal engineering. He graduated from the University of Tokyo receiving a Bachelor and Master in Engineering and finally a Doctor of Engineering from the same University. He worked for 35 years in research on coastal engineering in Central Research Institute of Electric Power Industry in Japan. His major field was the wave force acting on coastal structures such as rubble mound breakwaters. Over the second half of his career, he was involved in research on tsunami disasters. He participated in tsunami disaster surveys as a member of the Japanese team in Indonesia and the Independent State of Samoa as well as to the Tohoku area in Japan in 2011. In Jamaica, he has concentrated on beach erosion and shore protection work. Locations of photos on the front cover. Negril Morant Point Morant Bay Port Royal Annotto Bay Town Centre in An- Hellshire Beach Hope Bay notto Bay Hope Bay near the Plumb Point Light- west beach of Rocky east beach of Rocky Swift River house Point Point Pagee Beach and St. Magarets Bay Long Bay in Port- Buff Bay Cabarita Island in land Parish Mort Maria Alligator Pond Alligator Pond River beach near Norman Old Harbour mouth Manley Interna- tional Airport i Contents 1 Introduction 1 2WaterWaves 3 2.1RegularWaves..................................... 3 2.1.1 Definitionsofwaterwaves........................... 3 2.1.2 Deepwaterwave,shallowwaterwaveandlongwave............ 6 2.1.3 Velocityofwave................................. 6 2.1.4 Motionofwaterparticle............................ 7 2.1.5 Nonlinearwaves................................. 10 2.2PressureofWave.................................... 11 2.2.1 Hydrostaticpressure.............................. 11 2.2.2 Dynamicpressure................................ 11 2.3WaveShoaling...................................... 13 2.4WaveBreaking..................................... 16 2.5StandingWaves..................................... 18 2.6IrregularWaves..................................... 20 2.7WaveRefraction..................................... 23 2.8WaveDiffraction.................................... 25 3 Nearshore Currents 27 3.1MassTransportduetoWaves............................. 27 3.2BoreduetoBreakingWaves.............................. 29 3.3Undertow........................................ 29 3.4RipCurrent....................................... 29 3.5LongshoreCurrent................................... 30 4 Coastal Sediment Transport 31 4.1BedLoad........................................ 31 4.2SuspendedLoad..................................... 31 4.3Cross-shoreBeachChange............................... 31 4.4LongshoreBeachChange................................ 33 4.5 Equilibrium of Beaches ................................. 35 ii 5 Sediment Resources 35 5.1RiversasTransportationPathofSediment...................... 35 5.2CoralReefOrganisms................................. 40 6 Examples of Beach Erosion and Formation in Jamaica 43 6.1BeachErosioninAnnottoBay............................. 43 6.2BeachErosioninAlligatorPond............................ 45 6.3BeachFormationinRockyPoint........................... 52 7 Beaches in Jamaica 58 8 Concluding Remarks 91 iii List of Figures 1 Jamaican beach typologies (Government of Jamaica, 2017) [1]. ........... 2 2 Reef dataset (Maxam et al., 2011)[2]. ........................ 2 3 Definitionsofwaterwave................................ 3 4 Wave propagation. ................................... 4 5 Dispersionrelationship................................. 5 6 Velocityprofileofhorizontalcomponent........................ 7 7 Orbitalmotionofwaterparticlesduetowave..................... 8 8 Waterparticlemotionduetowaves(figuresarenotscaled)............. 9 9 ComparisonofprofilebetweenStokeswaveandlinearwave............. 10 10 Comparisonofprofilebetweencnoidalwaveandlinearwave............. 10 11 Hydrostaticpressureprofile.............................. 11 12 Pressureprofiles..................................... 12 13 Pressureprofiles..................................... 13 14 Waveshoaling...................................... 14 15 Shoalingcoefficient................................... 16 16 Definition of wave breaking with velocity at wave crest and wave celerity . 17 17 Breakers......................................... 18 18 Standingwave...................................... 19 19 Partialstandingwave.................................. 19 20 Superimpositionofdifferentfrequencywaves..................... 20 21 Wavetrain(wave-by-wave)analysis.......................... 21 22 AnexampleofpowerspectrumbasedonJONSWAPspectrum........... 22 23 Time series of irregular waves at different locations while propagating. ....... 23 24 Snell’s law for water waves ............................... 24 25 WaverefractionobservednearPalisadoes....................... 24 26 Mechanismofwaverefractiononseabedwithauniformslope............ 25 27 WavediffractionobeservedbehindanislandnearPortRoyal............ 26 28 SchematicdrawingofwavediffractioninKingstonHarbour............. 26 29 Masstransportvelocityprofiles............................. 28 30 Boreafterwavebreaking................................ 29 31 Ripcurrent....................................... 30 32 Longshorecurrent.................................... 30 33 Shoreline change patterns (Sunamura and Horikawa, 1974)[5] ............ 32 iv 34 Comparison with experimental results (Kajima et al., 1982[6]) ........... 33 35 Beachchangeduetolongshoresedimenttransportation............... 34 36 LongshoresandtransportobservedalongthecoastnearHabourview........ 34 37 LocationsofphotostakenalongtheYallahsriver................... 37 38 LocationsofphotostakenalongtheWagWaterriver................. 37 39 TheYallahsRiver.................................... 38 40 TheWagWaterRiver................................. 39 41 Crosssectionofcoralreef............................... 40 42 Planeviewofcoralreef................................. 40 43 Processfromcoralreeforganismstosediment[7]................... 41 44 PanelofNegrilEnvironmentalProtectionArea.................... 42 45 Phototoadvocatereplenishingwhitesandbycoralreefs............... 42 46 BeachintowncentreofAnnottoBay......................... 43 47 BeachfacingAnnottoBay............................... 43 48 CoastlinealongAnnottoBayandWagWaterRivermouth............. 44 49 BeachinAlligatorPond................................ 45 50 DamagesduetobeacherosioninAlligatorPond................... 45 51 CoastlinefromMilkRivertoAlligatorPond..................... 46 52 ComparisonofcoastlinesneratheMilkRivermouth................. 47 53 BeachchangeofLongBay,Manchester........................ 48 54 BeachfacingGreenBay................................ 49 55 ComparisonofcoastlinesfacingGreenBay...................... 49 56 BeachfacingGautierBayoneastsideofAlligatorPond.............. 50 57 ComparisonofcoastlinesfacingGautierBay..................... 50 58 BeacherosionfromeasttowestaroundAlliagtorPond................ 51 59 CoastlineofRockyPoint................................ 52 60 Rubbles on the beach indicating existence of groin in the past ........... 52 61 BeachontheeastsideinRockyPoint........................ 53 62 BeachonthewestsideinRockyPoint........................ 53 63 Comaprisonoftheeastsidebeach........................... 54 64 ComaprisonofthesoutheastcoastofRockyPoint.................. 55 65 CoastlinefromtheRioMinhoRivertoRockyPoint................. 56 66 Comparisonofthewestbeach............................. 57 67 Locationsofbeacheswherephotosweretaken..................... 58 v 68 AnexampleofphotosofbeachonGoogleEarthPro................ 58 69 Beach in Alligator Pond on 18th of October, 2017 .................. 59 70 Beach in Alligator Pond on 10th of June, 2018 .................... 60 71 BeachtotheeastofAlligatorPondinGreenbay.................. 61 72 BeachtotheeastofAlligatorPondinGautierbay................. 62 73 BeachatAlligatorPondRivermouth......................... 63 74 BeachinAnnottoBay................................. 64 75 BeachinAnnottoBaytowncentre.......................... 65 76 BeachinthesouthofBelmont,Westmoreland.................... 66 77 BeachinthenortheastofBuffBay.......................... 67 78 Beach in the east of Bull’s Bay, Hanover ....................... 68 79 BeachinHellshire.................................... 69 80 BeachnearHopeBay.................................. 70 81 BeachnearSwiftRiverinHopeBay......................... 71 82 BeachinHopewell................................... 72 83 BeachinJacksonBay.................................. 73 84 BeachinLongBay,PortlandParish.......................... 74 85 DeadEndBeachinMontegoBay........................... 75 86 DumpBeachinMontegoBay............................. 76 87 BeachinMorantBay.................................. 77 88 BeachinMorantPoint................................. 78 89 BeachofSevenMileBeachinNegril......................... 79 90 BeachinOldHarbour................................. 80 91 BeachinOrangeBay.................................. 81 92 BeachinPortAntonio................................. 82 93 BeachinPortRoyal................................... 83 94 BeachontheeastsideofRockyPoint......................... 84 95 BeachonthewestsideofRockyPoint........................ 85 96 BeachinRunawayBay................................. 86 97 BeachinRunawayBay................................