Recent Submissions

  • Florida's West Coast inlets: shoreline effects and recommended action

    Dean, Robert G.; O'Brien, M. P. (Department of Coastal and Oceanographic Engineering, University of Florida, 1987)
    This report responds to the 1986 Beaches Bill which, in recognition of thepotential deleterious impact on Florida's beaches of inlets modified for navigation,mandated a study of those inlets with identification of recommended action to reducethe impacts. This report addresses west Coast inlets; East Coast inlets are thesubject of a companion report.There are 37 inlets along that portion of Florida's West Coast commencing fromPensacola Bay Entrance to Caxambas Pass at the south end of Marco Island. Compared tothose on the East Coast, most West Coast inlets have not had the deleterious effectson the adjacent beaches, yet all modified inlets without proper management have thepotential of impacting unfavorably on the adjacent shorelines. Moreover, at presentthere is interest in opening three West Coast entrances which either have been openin the past (Midnight Pass) or which have opened occasionally (Navarre Pass andEntrance to Phillips Lake).A review of inlets in their natural condition demonstrates the presence of ashallow broad outer bar across which the longshore transport Occurs. These shallowand shifting bar features were unsuitable for navigation which in many cases has ledto the deepening of the channels and fixing with one or two jetty structures. Inlets in this modified state along with inappropriate maintenance practices have thepotential of placing great ero$ional stress along the adjacent beaches. Moreover.channel dredging can reduce wave sheltering of the shoreline by ebb tidal shoals andalter the equilibrium of the affected shoreline segments. The ultimate in poor sandmanagement practice is the placement of good quality beach sand in water depths toogreat for the sand to reenter the longshore system under natural forces; depths of 12ft. or less are considered appropriate for Florida in order to maintain the sand inthe system.With the interference of the nearshore sediment transport processes by inletsmodified for navigation, if the adjacent beaches are to be stabilized there must bean active monitoring program with commitment to placement of dredged material ofbeach quality on shoreline segments of documented need. Several East Coast inletshave such transfer facilities; however. the quantities of sand transferred should beincreased. Although an evolution and improvement in the technical capability tomanage sand resources in the vicinity of inlets is expected, an adequate capabilityexists today and a concerted program should be made to commence a scheduledimplementation of this capability at those entrances causing greatest erosionalstress on the adjacent shorelines.A brief summary review for each of the 37 West Coast inlets is presentedincluding: a scaled aerial photograph, brief historical information, several itemsrelated to sediment losses at each inlet and special characteristics relevant toState responsibilities. For each inlet, where appropriate, the above infor~tion isutilized to develop a recommenced action. (PDF has 101 pages.)
  • Beach monitoring project Sand Key Phase II Beach nourishment program (North Redington Beach and Redington Shores) Post-Nourishment Report Part II Offshore Profiles and Wave Data

    Lin, Li-Hwa; Dean, Robert G. (Coastal and Oceanographic Engineering Department, University of Florida, 1989)
    This study presents the third post-nourishment survey (January 1989) results forthe Sand Key Phase II beach nourishment project carried out in June, 1988. Themonitoring program to this beach nourishment project is a joint effort betweenthe University of South Florida and University of Florida. The field surveysinclude a total of 26 profiles, encompassing approximately 3 miles of shorelineextending from DNR R-96 to R-1ll. The total calculated volume loss of sand inthe nourished segment (from R-99G to R-107) between the July 88 and January 89surveys is 51,113 cubic yards, which is a loss about 9.7 percent of 529,150 cubicyards actually placed in the nourishment project. The total loss of sand computedin the entire survey area is 26,796 cubic yards, which is only 5.1 percent of thesand placed in the nourishment project. It is stressed that a part of these netvolume reductions is due to the background erosion and not due to spreading lossesinduced by the nourishment project. (PDF contains 168 pages.)
  • Some considerations on coastal processes relevant to sea level rise

    Mehta, Ashish J.; Dean, Robert G.; Dally, William R.; Montague, Clay L. (Coastal and Oceanographic Engineering Department, University of Florida, 1987)
    The effects of potential sea level rise on the shoreline and shore environmenthave been briefly examined by considering the interactions between sea level rise andrelevant coastal processes. These interactions have been reviewed beginning with adiscussion of the need to reanalyze previous estimates of eustatic sea level rise andcompaction effects in water level measurement. This is followed by considerations onsea level effects on coastal and estuarine tidal ranges, storm surge and water levelresponse, and interaction with natural and constructed shoreline features. Thedesirability to reevaluate the well known Bruun Rule for estimating shoreline recessionhas been noted. The mechanics of ground and surface water intrusion with reference tosea level rise are then reviewed. This is followed by sedimentary processes in theestuaries including wetland response. Finally comments are included on some probableeffects of sea level rise on coastal ecosystems.These interactions are complex and lead to shoreline evolution (under a sea levelrise) which is highly site-specific. Models which determine shoreline change on thebasis of inundation of terrestrial topography without considering relevant coastalprocesses are likely to lead to erroneous shoreline scenarios, particularly where theshoreline is composed of erodible sedimentary material.With some exceptions, present day knowledge of shoreline response to hydrodynamicforcing is inadequate for long-term quantitative predictions. A series of interrelatedbasic and applied research issues must be addressed in the coming decades todetermine shoreline response to sea level change with an acceptable degree ofconfidence. (PDF contains 189 pages.)
  • Part I. Hydraulics of tidal inlets: simple analytic models for the engineer

    Mehta, Ashish J. (Coastal and Oceanographic Engineering Department, University of Florida, 1975)
    Inlets are common coastal features around the world. Essentially aninlet connects a lagoon, a bay or an estuary to the ocean (or sea), and theflow through the inlet channel is primarily induced by the tidal rise andfall of water level in the ocean. When speaking of the hydraulics of an inlet,one is interested mainly in determining the flow through the inlet andthe tidal variation in the bay, given the following:(1) Inlet geometry(2) Bay geometry(3) Bottom sediment characteristics in the inlet(4) Fresh water inflow into the bay (and out throughthe inlet)(5) Ocean tide characteristicsA combination of all these factors can produce a rather complex situation. (PDF contains 34 pages.)
  • Inlet stability and case histories, Part II

    Mehta, Ashish J. (Coastal and Oceanographic Engineering Department, University of Florida, 1975)
    Inlets which require frequent channel dredging due to gradual shoaling,exhibit migration, or shoal up during storms, are in general unstable andpose a problem to the engineer. This problem of inlet stability is a complexone, because of the rather large number of variables that go into definingstability. The reference here is to inlets on sandy coasts only, becausethe absence of sand or similar sedimentary material the problem does notarise. Shell is also found in varying proportions with sand. Some of thisis. new, whereas in some areas it is ancient reworked material whose sizedistribution is close to that of the sand with which it is associated. (PDF has 24 pages.)
  • Determination of direction of littoral transport along the north shore of Santa Rosa Island, Florida

    Wang, Yu-Hwa; Chang, T. H.; Harrell, Sidney L. (Coastal and Oceanographic Engineering Department, University of Florida, 1977)
    The purpose of this study was to determinethe actual direction of littoral transport along the north shore of SantaRosa Island in the vicinity of Pensacola Beach, Florida. To accomplish thisobjective the sand tracer method was used for the study. Visual observationsand instrument recordings of the environment factors were also made duringthe tracing operations. The investigation covered a time span from September14, 1976 to March 12, 1977.(PDF contains 68 pages.)
  • Shoreline erosion due to extreme storms and sea level rise

    Dean, Robert G. (Coastal and Oceanographic Engineering Department, University of Florida, 1983)
    A summary is presented of research conducted on beach erosion associated withextreme storms and sea level rise. These results were developed by the author andgraduate students under sponsorship of the University of Delaware Sea Grant Program.Various shoreline response problems of engineering interest are examined. Thebasis for the approach is a monotonic equilibrium profile of the form h = Ax2 /3 inwhich h is water depth at a distance x from the shoreline and A is a scale parameterdepending primarily on sediment characteristics and secondarily on wavecharacteristics. This form is shown to be consistent with uniform wave energydissipation per unit volume. The dependency of A on sediment size is quantifiedthrough laboratory and field data. Quasi-static beach response is examined torepresent the effect of sea level rise. Cases considered include natural and seawalledprofiles.To represent response to storms of realistic durations, a model is proposed inwhich the offshore transport is proportional to the "excess" energy dissipation perunit volume. The single rate constant in this model was evaluated based on largescale wave tank tests and confirmed with Hurricane Eloise pre- and post-stormsurveys. It is shown that most hurricanes only cause 10% to 25% of the erosionpotential associated with the peak storm tide and wave conditions. Additionalapplications include profile response employing a fairly realistic breaking model inwhich longshore bars are formed and long-term (500 years) Monte Carlo simulationincluding the contributions due to sea level rise and random storm occurrences. (PDF has 67 pages.)
  • Coastal engineering investigation at Jupiter Inlet, Florida

    Buckingham, William T. (Coastal and Oceanographic Engineering Department, University of Florida, 1984)
    A fixed-bed hydraulic model of Jupiter Inlet, Florida, wasconstructed for the purpose of testing measures designed to remedyproblems of sediment erosion and deposition in the inlet area. Bothtide-induced flows as well as waves were simulated in the model whichwas built on an undistorted scale of 1:49. Model verification was basedon prototype measurements of waves, tides and currents. Results havebeen interpreted in terms of the influence of various proposed remedialschemes on flow velocity magnitude, distribution and wave height atvarious locations within the study area. A stability parameter has beenutilized for evaluating the degree of sediment erosion or deposition ata given location.Various structural solutions were examined in the model. It isproposed that, in the initial phase of solution implementation, sedimentremoval/nourishment methods be used primarily to mitigate the existingproblems. New structures, as per model test results, should beinstalled under subsequent phases, only if sediment managementprocedures do not prove to be adequate. The currently followedprocedure of periodic sand trap dredging may be extended to include thenew dredging/nourishment requirements. (PDF contains 245 pages.)
  • Sediment budget: principals and applications

    Dean, Robert G. (Coastal and Oceanographic Engineering Department, University of Florida, 1996)
    The framework of sediment budget concepts provides a formalized procedureto account for the various components of sediment flux and the changes ofvolume that occur within a given region. Sediment budget methodology can beuseful in a number of coastal engineering and research applications,including: inferring the amount of onshore sediment transport for a nearshoresystem that contains an "excess of sediment", determining sediment deficits todowndrift beaches as a result of engineering works at navigational entrances,evaluating the performance of a beach nourishment project, inferring thedistribution of longshore sediment transport across the surf zone, etc.This chapter reviews briefly the governing equations for sediment budgetcalculations, considers various measurement and other bases for determiningthe sediment flux components necessary to apply the sediment budget conceptand finally for illustration purposes, applies the sediment budget concept toseveral examples. (PDF contains 52 pages.)
  • Two-dimensional finite-difference model for moving boundary hydrodynamic problems

    Liu, Yuming (University of Florida, Department of Coastal and Oceanographic Engineering, 1988)
    To predict the hydrodynamics of lakes, estuaries and shallow seas, a two 'dimensionalnumerical model is developed using the method of fractional steps. Thegoverning equations, i.e., the vertically integrated Navier-Stokes equations of fluidmotion, are solved through three steps: advection, diffusion and propagation. Thecharacteristics method is used to solve the advection, the alternating direction implicitmethod is applied to compute the diffusion, and the conjugate gradient iterativemethod is employed to calculate the propagation. Two ways to simulatethe moving boundary problem are studied. The first method is based on the weirformulation. The second method is based on the assumption that a thin water layerexists over the entire dry region at all times. A number of analytical solutions areused to validate the model. The model is also applied to simulate the wind drivencirculation in Lake Okeechobee, Florida.(135 page document)
  • Survey Data Report: Cape Canaveral, March-July, 1988 Volume 1

    Kirby, James T. (Coastal and Oceanographic Engineering Department, University of Florida, 1998)
    This report presents the results of a bathymetric surveying program carriedout on the beach and nearshore region about 1 km to the north of the PortCanaveral inlet. The survey data covers a period between March 16 and July 21,1988. The data was collected in support of a field study on directional wavemeasurement and Bragg reflection from artificial, shore-parallel bars, performedduring June-July, 1988. The topography at the experiment site was generallymonotonic in the on-offshore direction (except near the end of the experimentalprogram) and uniform in the longshore direction. (64 pages)
  • Flow and transport characteristics at a canal network: Burnt Store Isles, Punta Gorda, Florida

    Wang, Hsiang; Lee, Jung L.; Lin, Lihwa (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This report presents results of field measurements and numerical modeling of thehydrodynamic and sedimentary behaviors at a boat lock located in Section 15, BurntStore Isles of Punta Gorda, Florida. The purpose of the study is to establish thequantities of tidal flows through the lock in comparison with the flows bypassing thelock through other outlets between Section 15 and the Alligator Creek. The amountof sediment and pollutant transporting through the lock are also estimated in thestudy. (68 pp.)
  • Historical shoreline response to inlet modifications and sea level rise (M.S. Engineering Thesis)

    Grant, Jonathan R. H. (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This thesis examines the historical shoreline response to inlet modifications and sealevel rise. Inlet modifications are considered to be the geographic stabilization and training(through the use of structures) of natural inlets and the creation and further modification ofartificial inlets. Shoreline response to natural and artificial processes must be understood inorder to predict the performance of the coastline. The tendency for creating and modifyinginlets increases as industry and population growth demands. Sea level rise is a natural processwhich cannot be controlled at this time. Current theoretical approaches to predictingshoreline response indicate that sea level rise and inlet modifications can cause substantialshoreline impact. Florida, with roughly a century of shoreline position and relative sea leveldata, provides a basis for examining past trends and comparing them with theory.The shoreline of Florida was found to be accreting with the greatest accretion alongthe east coast. Shoreline responses within the boundaries of the erosional influence of inletsdue to their creation and/or modification were examined for 19 inlets around the coast ofFlorida. The differences in the shoreline response before and after the initial modification ofeach inlet show the erosional strain that inlets apply on the nearby shoreline. The effect onshoreline response due to the human intervention (unnatural processes) of modifying inletswas isolated and examined. The shoreline response due to this "human intervention" was erosional, thereby showing the negative impact that modified inlets have on shorelines. Thisinduced erosion is responsible for the loss of roughly 21.6 million cubic yards of sand from theshoreline that is within the erosional influence of Florida's east coast inlets. Combining theshoreline changes due only to natural processes with sea level rise data allows for comparisonwith the commonly accepted Bruun Rule for shoreline response as a result of a changingsea level. This comparison and the effects of including a lag time between a rise in sea leveland a change in shoreline along the east coast of Florida during the last century show noagreement with the Bruun Rule and no correlation with a specific lag time. (153 pp.)
  • Perdido Key Beach nourishment project: Gulf Islands National Seashore 1991 annual report

    Work, Paul A.; Dean, Robert G. (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This report is the second annual report in a continuing series documenting a fieldproject within the Gulf Islands National Seashore at Perdido Key, Florida. The field projectincludes the monitoring of a number of physical parameters related to the evolution of thePerdido Key beach nourishment project. Approximately 4.1 million m3 of dredge spoilfrom Pensacola Pass were placed upon approximately 7 km of the Gulf of Mexico beachesof Perdido Key between November, 1989, and September, 1990.Beach profile data describing the evolution of the nourished beach are included, aswell as wave, current, tide, wind, temperature, and rainfall data to describe the forces influencingthe evolution. Data describing the sediment sizes throughout the project areaare also included. A brief discussion of the data is included; a more detailed analysis andinterpretation will be presented in the lead author's Ph.D. dissertation. (313 pp.)
  • Barrier island erosion and overwash study -- effect of seawalls. Volume 2

    Srinivas, R.; Dean, Robert G.; Parchure, T. M. (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This is the second of a pair of reports documenting the effects of storms on beach systemsincluding the presence of seawalls. With the aim of simulating the effects of overwash onbarrier islands with seawalls and characterizing their response, a series of eight experimentswas conducted at the Coastal Engineering Laboratory of the University of Florida. The barrierisland was simulated by a 400 feet wide horizontal crest and an initially uniform mildly-sloped(1:19) beach. The effects of positioning the seawall at two different locations as well as the effectsof various storm surge levels and accompanying overtopping were investigated. Experimentswere conducted with both regular and irregular storm waves. With the seawall located at theslope break between the crest and the sloping beach of the barrier island, and the crest of theseawall just submerged in sand, the effects on the sediment transport process were found to beminimal. For the same position of the seawall but with the crest of the seawall raised above thesurrounding ground level, overtopping caused washover of sand indicating substantial transportin suspension. Increased levels of overtopping tended to accentuate bed profile changes butsupress bar formation (as did irregular waves). Positioning the seawall at the Mean Sea Levelshoreline caused significant scour both immediately landward as well as immediately seawardof the seawall. A prominent scour trough developed further seaward. The longshore bar washighly three-dimensional. It appears that seawalls need to be located adequately landward of theshoreline to discharge their function effectively without adverse effect to the beach. In addition,concerns for safety warrant the presence of an adequate buffer-zone between the seawall andthe upland property. (61 pp.)
  • Barrier island erosion and overwash study - volume 1

    Srinivas, R.; Dean, Robert G; Parchure, T. M. (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This is the first of a pair of reports documenting the effects of storms on barrier island systems.The present report (Volume 1) investigates storm effects on natural island conditions whereasVolume 2 addresses the effects of seawalls. With the aim of simulating the effects of overwashon barrier islands and characterizing their response, a series of nine experiments was conductedat the Coastal Engineering Laboratory of the University of Florida. The barrier island wassimulated by a 400 feet wide (prototype units) horizontal crest and an initially planar (1:19)beach. The effects of various storm surge levels and accompanying overtopping were investigated.Experiments were conducted with both regular and irregular storm waves. Regularwaves without overtopping caused the formation of a substantial berm in the swash zone and aprominent longshore bar offshore. Increasing degrees of overtopping resulted in substantial lossof sand from the barrier island system. The longshore bar was considerably more subtle for thehighest water level tested (11.5 ft. above mean sea level). Simulation of a storm-surge hydrographwith rising and falling water levels indicated that the presence of the bar tends to occuronly during a relatively steady or slowly changing water level. The experiments with irregularwaves were conducted with reasonably similar wave heights and carrier periods as those withregular waves. The major difference was in the characteristics of the longshore bar response. Incomparison with cases with regular waves, the bar was less distinct without overtopping, subtlewith minimal overtopping and absent in cases with substantial overtopping. These experimentsseem to indicate that offshore bars are simply break-point bars which require a fairly steadybreak-point and undertow (return of mass transport) for optimal formation. (Document has 84 pages.)
  • Flow and transport characteristics at a canal network Burnt Store Isles, Punta Gorda, Florida

    Hsiang, Wang; Lee, Jung L.; Lin, Lihwa (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This report presents results of field measurements and numerical modeling of thehydrodynamic and sedimentary behaviors at a boat lock located in Section 15, BurntStore Isles of Punta Gorda, Florida. The purpose of the study is to establish thequantities of tidal flows through the lock in comparison with the flows bypassing thelock through other outlets between Section 15 and the Alligator Creek. The amountof sediment and pollutant transporting through the lock are also estimated in thestudy. (Document has 68 pages.)
  • Historical shoreline response to inlet modifications and sea level rise

    Grant, Jonathan R. H. (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This thesis examines the historical shoreline response to inlet modifications and sealevel rise. Inlet modifications are considered to be the geographic stabilization and training(through the use of structures) of natural inlets and the creation and further modification ofartificial inlets. Shoreline response to natural and artificial processes must be understood inorder to predict the performance of the coastline. The tendency for creating and modifyinginlets increases as industry and population growth demands. Sea level rise is a natural processwhich cannot be controlled at this time. Current theoretical approaches to predictingshoreline response indicate that sea level rise and inlet modifications can cause substantialshoreline impact. Florida, with roughly a century of shoreline position and relative sea leveldata, provides a basis for examining past trends and comparing them with theory.The shoreline of Florida was found to be accreting with the greatest accretion alongthe east coast. Shoreline responses within the boundaries of the erosional influence of inletsdue to their creation and/or modification were examined for 19 inlets around the coast ofFlorida. The differences in the shoreline response before and after the initial modification ofeach inlet show the erosional strain that inlets apply on the nearby shoreline. The effect onshoreline response due to the human intervention (unnatural processes) of modifying inletswas isolated and examined. The shoreline response due to this "human intervention" was erosional, thereby showing the negative impact that modified inlets have on shorelines. Thisinduced erosion is responsible for the loss of roughly 21.6 million cubic yards of sand from theshoreline that is within the erosional influence of Florida's east coast inlets. Combining theshoreline changes due only to natural processes with sea level rise data allows for comparisonwith the commonly accepted Bruun Rule for shoreline response as a result of a changingsea level. This comparison and the effects of including a lag time between a rise in sea leveland a change in shoreline along the east coast of Florida during the last century show noagreement with the Bruun Rule and no correlation with a specific lag time. (Document has 153 pages.)
  • Sebastian Inlet physical model studies. Final report: movable bed model

    Wang, Hsiang; Lin, Lihwa; Miao, Gang (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    This report presents results of the experiments of the existing inlet and eightstructural alternatives to the Sebastian Inlet from a movable bed model. It is intendedto find solutions for improvement of boating safety and protection of beaches adjacentto the inlet. Based upon the experimental results from here and the fixed bed modelstudy, which is summarized in Part I report, an optimum structural modification planwas then recommended providing a general frame of improvement scheme.The research in this report was authorized by the Sebastian Inlet District Commissionof September 15, 1989. The University of Florida was notified to proceedon November 14, 1989. The study and report were prepared by the Department ofCoastal and Oceanographic Engineering, University of Florida. Coastal TechnologyCorporation was the technical monitor representing the Sebastian Inlet District. (Document has 109 pages.)
  • Laboratory experiments on cohesive soil bed fluidization by water waves (M.S. Engineering Thesis)

    Feng, Jingzhi (University of Florida, Coastal and Oceanographic Engineering Department, 1992)
    The mechanism by which fluid mud is formed by water wave motion over coastal andestuarine cohesive soil beds is of evident interest in understanding and interpreting themicrofabric of flow-deposited fine sediments in shallow waters, and hence the erodibilityof muddy beds due to hydrodynamic forcing. This study investigated water wave-inducedfluidization of cohesive soil beds composed of a 50/50 (by weight) mixture of a commercialattapulgite and a kaolinite in a laboratory flume. Temporal and spatial changes of theeffective stress were measured during the course of wave action, and from these changesthe bed fluidization rate was calculated. A previously developed hydrodynamic wave-mudinteraction model of the two-layered water-mud system was employed to study the natureand the degree of wave dissipation, in terms of energy dissipation rate, during the bed fluidizationprocess. By evaluating the mud rheological properties separately, a mud viscositymodel was developed, which was then used in conjunction with the wave-mud interactionmodel to obtain an effective sheared thickness of the bed resulting from wave action. Thisthickness, considered to be a representative of the fluidized mud thickness, was comparedwith the latter obtained from pressure measurements. Also, through this wave-mud modelthe relationship between the rate of fluidization and the rate of wave energy dissipationduring fluidization was examined. In general, for a given wave frequency, a larger wave fluidized the bed at a faster rateand to a greater depth than a smaller one. Furthermore, increased bed consolidation timedecreased the rate of fluidization due to increased mud rigidity. The rate of bed fluidizationwas typically greater at the beginning of wave action and decreased with time. Eventuallythis rate approached zero, while in some cases the wave energy dissipation rate approached aconstant value, which increased with wave height. As the fluidization rate approached zero,there appeared to occur an equilibrium value of the bed elevation, and hence a fluid mudthickness, for a given wave condition. During the fluidization process the bed apparentlylost its structural integrity by loss of the effective stress through a build-up of the excesspore water pressure. After wave action ceased, the bed structure exhibited recovery bydissipation of the excess pore water pressure.Further studies will be required in which the hydrodynamic model must be improved viaa more realistic description of mud rheology and relaxation of the shallow water assumption,and better pressure data must be obtained than in the present study. Nevertheless, thisinvestigation has been instructive in demonstrating relationships between the degree of mudfluidization, wave energy dissipation and bed consolidation time, and thus offers insight intoan important mechanism by which coastal and estuarine muds are eroded by wave action. (Document has125 pages.)

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