CoastalChange on the TimeScale of Oecadesla !filiffennia Passiveairborne multi-spectral remote sensing application to nearshore, acean-floor mapping and geology EbitariIsoun', charlesFletcher', Neil Frazer!,Jodi I-larney',and JonathanGradiez 1University of Hawaii, Manoa, Department of Geology and Geophysics, 1680East-west Rd.,posT 721 Honolulu, ~I 96822, u.s.A. e-mail Isoun!:ebitari@soest hawaii.edu e-maillFietcher!. fletcherosoest hawaii.edu e-mail Frazer!:neilosoest.hawaa.edu e-mail Harney!:[email protected] 2!onathanGradie Terra systems nc.Earth & planetRs,suite 264, 2800 woodlawn Dr., Honolulu, Hl96822, u s,A, e-mailigradie!Ter rasys. corn Airbornedigital multi-spectral images collected in fourdiscrete narrow bands 88, 551,557, 701nm; width of 10nm! providehigh resolution mapping capabilities in near-shoremarine environments. The digital database for thisproject con- sistsof informationfor depthsup to -35min KailuaBay; a typicalfringing reef environment on windwardOahu, Hawaii. Subsequentphysical modeling of the multi-spectralcomponents is usedto deconvolvethe spectraleffects of the atmos- phere,water column and benthic substrates to obtain depth and bottom-type maps, Using high-resolution USGS bathym- etrysurvey data collected at two sectionsof the bayfor errorassessment, the physicalmodel achieves 80'in accuracy in predicteddepth. Spatial clustering of the bottom-typepredictions are supported by extensiveground truthing and field knowledgeas well as low error in depthpredictions. Fifteen classes are mapped that reflect variations in ecologyand sed- imentarycharacter of the ocean floor. The usefulness of this model lies its flexible application to this and other spectral data types collected in marine environments. 10S CoasraiChange on the TimeScafe of Oecades o INIIennia Measuring and modeling coastal progradation, catastrophic shoreline retreat. and shoreface translation along the coast of Washington State, USA GeorgeM. Kaminskyi,Harry M. Jol2,Peter J. Cowell3,Peter Ruggieroi and Guy Gelfenbaum4 I WashingtonDepartment of Ecology, Coastal Monitoring IS Analysis Program, PO. Box 47600 0ympia, WA 98504-7600. U.S.A. e-mai Kaminsky!:gkam461@ecy wa.gov e-mail Ruggiero!.prug461@ecy wa gov Universityof Wisconsin,-EauClaire, Department of Geography.Eau Claire. Wl 54702,U.S.A. e-mail:iolhrnouwec.edu 3 Universityof Sydney, School of Geosciences,Coastal Studies Unit, NSW 2006, AUSTRALIA e-mail P COWel!QCSu.usyd.edu.au 4USGeological Survey, 345 Middlefield Road, MS 999, Menlo Park, CA 94025, U.S.A. e-mail:gelfsaoctopuswr usgs.gov A multi-disciplinaryresearcih program, the SouthwestWashington Coastal Erosion Study, is investigatinga regional coastalsedimentary system along the tectonicallyactive margin of PacificNorthwest of the UnitedStates, The study area is knownas the ColumbiaRiver ittoral cell,a 165-kmreach of coastthat hasaccumulated Columbia river sand along four barrier-plairisubcells separated by the largedepositional estuaries of WillapaBay and GraysHarbor. As a componentof the study,the late Holoceneand historical post 1870's!evolution of barriersalong the SouthwestWashington coast is being investigatedto determinethe relationshipbetween net progradationand sedimentsupply rates and the influence of intermittentearthquake-induced subsidence events that occurat approximately500 yearintervals. Extensiveground penetratingradar GPR!surveys have been conducted to map the nearsurface stratigraphy upper 4 6 m! and morphologicalchange of the progradedcoastal barriers spanning time scalesof yearsto millennia.High-resolu- tian GPRtopographically corrected with real time kinematicdifferential global positioning systems RTK DGPS! has been usedto obtain detailedimages of the depositionalhistory following the most recentsubsidence events, which are typi- cally markedin the subsurfaceby heavymineral layers. Oifferences in the GPRreflection packages suggest changes in depositionalprocesses, rates, and periods.High resolutionGPR reflection data is allowing reconstructionof shoreline behaviourbetween timelines obtained from eitherhistorical records or variousdating techniques bulk and AMS 14C,and optical!. In particular,the high-resolutionGPR profiles allow for comparisonof coastalchanges since the lastearthquake- inducedsubsidence event of January,1700 to thosesince the late 1800's,when the coastbecame subject to humaninter- vention e.g.jetties, dams, irrigation, dredging!. A majorobjective of this researchis to gain a betterunderstanding of the time scaleassociated with morphologicalchanges such as the post-subsidencerebound and morphologicaladjustment of the inner shelf and upper shoreface to an equilibrium condition. Timelinesand geometricparameters derived from GPRprofiles, historical shoreline and bathymetricmaps, and recent batihyrnetricsurveys, are beingused to conductsimulations of the evolutionarysequence of the coastalbarriers and inner shelf. The observedcycles of episodicsubsidence events and subsequentrebound and net progradationare simulated with the ShorefaceTranslation Model STM!,a mass-budgetgeometric profile modeldriven by sea-levelchange, littoral transport budgets, and morphological parameters.These simulations illustrate the interaction of the barriersand shoreface and helpto determinethe rangeof possibilitieswhich could accountfor net seawardprogradation, such as sedimentsup- ply from the ColumbiaRiver, and/or sedimentsupply from the lower shoreface.The exchangeof sedimentbetween the inner shelf and upper shorefaceand the role of the ower shorefacein ong-term nearshoremorphology and shoreline dynamiCSiS alSO being inVeStigatedwith high reSOlutianmultibeam bathymetry and nearShOreSurVeyS. The integrationof data sets,and in particular,the combinationof geophysicalobservations and simulationsof morpho- logic changeis enhancingboth the quantificationand conceptualunderstanding of coastalevolution over time scales especiallycenturies! that have formerly been speculative due to a lack of data. Resultsof these efforts can be used to refinebehaviour-oriented models and predictivecapabilities of future coastalchange. 107 CoastalChange on the TimeScale of Oecadesto Miltennra Contemporary evolutional trends of the central Polish coast Leszek J. Kaszubowski Departmentof GeotechnIcalEngineering, Technical University of Szczecin,70-310 Szczecin, Al. Piastow50 a, POLAND e-mail:[email protected] Introduction The Polishcoast is situated along the southern part of the Baltic Sea.The central Polishcoast is here defined as extend- ingfrom Darl6wek to Karwia Fig, 1!. From the standpointof hydrology,the BalticSea is an exceptionally diversified water basin.The reason for thisphenomenon isthe particularconfiguration of theshores, deeply indented fed ta variousdegrees by fluvialwaters, and differentlysituated in regardto the AtlanticOcean Mikulski,1986!. Thecentral Palish coast lies in a moderate,cool climatic zone. The regional climate is influenced by both the Atlantic Ocean and by the EastEuropean continent. The present outline of the centralPolish coast is the resultof a complexevolution of the BalticSea throughout the entire Holocene.During the last 8000 years,the Balticbasin had a permanentconnection withthe NorthSea Kaszabowski, 1988a, 1992!. Glabal transgressions and regressians, which occurred during that peri- od, left their mark on the Baltic Sea. Contemporary Evolutional Trends Spitshores predominate along the central Polish coast Fig. 2!, Inthis region, beaches are often wide, built of sandysed- iments,and the adjacentsea floor has abundant in numerousunderwater forms, mostly represented by bars.Scarce, high fluvioglacial-glaciogenicshares near Razewie sector 4,5; Fig 2! havedifferent dynamic features. The Rozewie cliff pro- truding far into the sea,while inert at presentwas very dynamicuntil recently.Between 1837-1875, the CapeRozewie recededby 90 m, at an averagerate of 2.35 rn/yr Szopowski,1961!. At the beginningof the 20th century,this section wasprotected. The Chlapowo cliffs are sandy gravel cliff debris,and in someplaces landslides of tills. n manyplaces along the cliff profile, a distinctslide step is found, which is evidenceof landslidestriggered off by catastrophicstorms at the end of the 19th andearly 20th centucy Subotowicz, 1984!. Measurements between 1971-1975 Subotowicz, 1984! indi- catethat the westernsection called Jastrzebia G6ra cliff, recedesat the rateof 0.5m/yr Fig.2!. Spitcoasts in this areaare the mostdeveloped Polish coasts of this type.They have a complexgeological farm, and areoften 3-4 km wide. Thecen- tral Polishcoast has been receding southwards during the 1980's.The lowest erosion rate of 0,2 m/yr,is recordedin Kar- wia sector5, Fig.2!, Furtherwestwards, in the regionof Lubiatowaand Leba, the rateof the seashore recession is high and amountsto 1 m/yrand 0,8 m/yr respectively sector 6,7; Fig.2!. Thedistinct erosion of spitshores is alsopointed out by E.Zawadzka 986!. Accordingto her,these shores are shifting southwards at the rate of 0.5-1.5 m/yr. However, some researchers Mielczarski, 1972, 1978, 1989! claim that the Polish coastrests in relativedynamical equilibrium. This apparent effect is undoubtedlycaused by generalstraightening of the shoreline, and by the irregularcharacter of coastalprocesses, Somewhat westwards from Gardno Lake sector 8, Fig.2!, theglaciagenic-fluvioglacial coast between 1960-1978 has receded with a rateof 0.2-1.8m/yr Miotk.and Bogaczewicz- Adarnczak,1986!. The fluvioglacial-glaciogenic shores near Jaraslawiec, between 1842-1922 have receded with