Study of the Evolution of a Beach Nourishment Project Based on Computer Models J. Galofre,* FJ Montoya

Total Page:16

File Type:pdf, Size:1020Kb

Study of the Evolution of a Beach Nourishment Project Based on Computer Models J. Galofre,* FJ Montoya Transactions on the Built Environment vol 9, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509 Study of the evolution of a beach nourishment project based on computer models J. Galofre,* F.J. Montoya," R. Medina* o Tarragona Coastal Service, Coastal Department, Ministry of Public Works, Transportation and Environment, PL Imperial Tarraco, 43005 Tarragona, Spain * Ocean and Coastal Research Group, Universidad de Cantabria, Dpto de Ciencias y Tecnicas del Agua u del Medio Ambiente, Avda. de los Castros s/n, Santander 39005, Spain Abstract This paper describes the role of beach change numerical modeling in the study of the evolution of a beach nourishment project. A brief review of the processes involved in the evolution of a nourished beach is made. Available models for sim- ulating the different processes are classified by means of the spatial and temporal scale they solve. This classification is used to determine present needs of new models and to select the appropriate existing model. Capabilities of models and application of models to the prediction of a project's performance is discussed. A set of models for the study of the evolution of a beach nourishment project based on numerical and empirical models is proposed. These models are applied to a beach nourishment project in Spain. 1 Introduction Beach nourishment is a major area of concern in the field of coastal engineering. Prediction of the performance of a beach nourishment project has received con- siderable attention during the last decades (see Work and Dean^, as a general reference). Although the sediment processes involved in the changes of a beach are nonlinear and have great variability both in space and in time, prediction of beach evolution with numerical models has proven to be a powerful technique that can be used to assist in the determination of project design and/or eval- Transactions on the Built Environment vol 9, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509 250 Computer Modelling of Seas and Coastal Regions Table 1: Beach Forcings Short Term Middle Term Long Term Waves Platform-Currents Winter-Summer Waves Tides Fortnight-tides Platform Currents Waves-cur rents Storms M.S.L. variations uation. Furthermore, numerical models describing the response of beaches to different coastal forcing have become increasingly numerous and sophisticated in the recent years. At present, however, there is no model that can be used to solve all the spatial and temporal scales of variability involved in beach nourishment evolution and, consequently, different models must be used. This paper describes the use of numerical models (either physics-based or empirical) in the evaluation of a beach nourishment project. Various types of numerical models are used. The models are classified by their spatial and tem- poral domains of applicability. The objective of the work is to propose a set of models for the study of a beach nourishment evolution that takes into account the different scales of variability. 2 Processes, Scales and Tools Erosion, accretion and beach change in offshore bottom topography are controlled by wind, waves, currents, water level, nature of the sediments and its supply and coastal structures. The time scale of variability of these forcings varies from short-term (less than 15 days), middle term (15 days to 6 months) and long term (years), see Table 1. The response of beaches to these perturbations and variable forcing can be found in a wide range of spatial scales, see Table 2. Besides the wide range of temporal and spatial scales of variability, coastal evolution processes are often three-dimensional., Still, important aspects of the coastal behaviour can be understood and predicted on the bases of lower-dimensional models that take advantage of the circumstance that the response of a beach of- ten exhibits a different behaviour with essentially different length scales in three mutually orthogonal space directions (vertical, cross-shore and longshore) (De Vriend*). This has led to a range of numerical models that focus on a particular time Transactions on the Built Environment vol 9, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509 Computer Modelling of Seas and Coastal Regions 251 Table 2: Beach Responses Small Scale Meso Scale Large Scale Bed forms Profile changes Coast-line erosion Beach cusps Planform changes Coast-line accretion Bars Crescentic bars Eustatic response Table 3: Models Short Term Middle Term Long Term Small Scale Meso Scale Large Scale Wave propagation Wave propagation Wave propagation Forcing Tide propagation Tide propagation Tide propagation Waves- cur rents Waves- currents Waves- currents Profile models Profile models Parametric models Response Local sed. transp. N lines models N lines models or space scale and a particular forcing (e.g. wave propagation models) or beach response (e.g. one line models), see Table 3. 3 Beach Evolution Models To improve predictive models for beach response, an accurate description of the forcing is necessary. From Table 3, it can be seen that existing hydrodynamic models (wave-, tide-propagation and wave induced currents) can be used for solv- ing the forcings at almost all spatial scales of interest. The choice of a particular model should be done in relation to the response model to be used. When selecting a response model, several physical facts must be taken into account. Cross-shore transport is very important just after the fill. A nourished beach reaches its equilibrium profile within the first year after the fill (Kamphuis and Moir*. Several existing models can describe the post-fill evolution of the profile (usually neglecting longshore transport). However, cross-shore transport at greater time scales (month to years) remains a challenging problem that has not received a great deal of attention (Work and Dean ^). Transactions on the Built Environment vol 9, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509 252 Computer Modelling of Seas and Coastal Regions Longshore sediment transport is found to be important near the shoulders of the fill in the beginning. Effects of the longshore gradients propagate after- wards into the nourished region. N-line models can represent these changes of the coastline in the mid-long term. The one-line approach imposes limitations by neglecting the influence of cross-shore transport. However, this can be over- come if the model is calibrated adequately (Hanson and Kraus*). For the long term evolution prediction, parametric models (e.g. equilibrium profile-coastline models) and statistical models (e.g. P.C.A. models) can help N-line models. Still better models are desirable. In this study we focus on the mid-long term evolution of a beach fill. Con- sequently, profile models are not considered. One-line model is selected for the prediction of the mid-long term evolution of the coastline. A propagation model based on the mild slope equation is chosen in order to solve the wave propagation. This kind of model is assumed to be adequate for the needs of the one-line model. A wave-induced current model is also used to better understand the results of the one-line model. Following Medina et al * a 3-way P.C.A. model is used for the long-term scale. 4 Altafulla Case Study 4.1 Field Site and Data Collection The site of the field study is Altafulla (Fig. 1), a sandy beach located 10 km north of Tarragona and 80 km south of Barcelona, on the Mediterranean Coast of Spain. Altafulla is a half-opened beach 2.3 km long located between two capes, "Els Munts" to the east and "Tamarit" to the west. A small river flows during storms in the middle of the beach. There are two predominant directions of wave approach: SW and E. More than three-quarters of the deep-water waves approach Altafulla from those sec- tors. The annual average significant wave height is about 0.5 m with typical winter storm waves of Hs of about 3 meters. Tides at Altafulla are negligible. The native beach sand has a mean diameter between D$Q — 0.12 to 0.2 mm and the beach profile slope changes from 1.2% to 2% from shoreline to bathymetric -5 meters. This bathymetric contour is considered the profile closure depth at Altafulla. This value was determined from the three-year monitoring program of profile changes. The bottom of the sea is sandy up to the 10 m bathymetric contour line. Transactions on the Built Environment vol 9, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509 Computer Modelling of Seas and Coastal Regions 253 27CO 2900 3100 3333 =530 3700 Figure 1: Site Location Map 4.2 Beach Nourishment Several erosion problems occurred in the northern part of the beach. A seawall was built to prevent backshore building damage. Southward littoral drift has been theorized as a major factor in the erosion that has been witnessed on Altafulla. A beach nourishement project was undertaken in 1989. Beach nourishment started in late 1990 and was completed in 1991. The Beach nourishment works consisted of 160,000 m^ of borrowed sand volume. Borrowed sand had a median diameter averaging D$Q = 0.6 mm. A detached breakwater was also built in the middle of the beach (see Fig. 1). The breakwater was 100 m long and was placed at the 5 m bathymetric contour line. 4.3 Monitoring Program A monitoring project is being carried out to evaluate the evolution of the fill. The monitoring program started in 1991 at the conclusion of the fill. The field program includes bathymetric beach profile and sediment samples. Profile surveys are taken every two months. Each profile is surveyed from permanent monuments landward to a depth of approximately 10 meters. Sediment samples are collected along three profiles simultaneously with the profile survey.
Recommended publications
  • Shoreline Response to Multi-Scale Oceanic Forcing from Video Imagery Donatus Bapentire Angnuureng
    Shoreline response to multi-scale oceanic forcing from video imagery Donatus Bapentire Angnuureng To cite this version: Donatus Bapentire Angnuureng. Shoreline response to multi-scale oceanic forcing from video imagery. Earth Sciences. Université de Bordeaux, 2016. English. NNT : 2016BORD0094. tel-01358567 HAL Id: tel-01358567 https://tel.archives-ouvertes.fr/tel-01358567 Submitted on 1 Sep 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSE PRÉSENTÉE POUR OBTENIR LE GRADE DE DOCTEUR DE L’UNIVERSITÉ DE BORDEAUX ÉCOLE DOCTORALE SPÉCIALITÉ Physique de l’environnement Par Donatus Bapentire Angnuureng Shoreline response to multi-scale oceanic forcing from video imagery Sous la direction de : Nadia Senechal (co-directeur : Rafael Almar) (co-directeur : Bruno Castelle ) (co-directeur :Kwasi Appeaning Addo) Soutenue le 06/07/2016 Membres du jury : M. HALL Nicholas Professor Université de Toulouse Président M. ANTHONY Edward Professor CEREGE, Aix-Provence Rapporteur M. OUILLON Sylvain Professor IRD-LEGOS Rapporteur M.RANASINGHE Roshanka Professor UNESCO-IHE, Pays-Bas Rapporteur Titre : Réponse de shoreline à forçage océanique multi-échelle à partir d’images vidéo Résumé : Le but de cette étude était de développer une méthodologie pour évaluer la résilience des littoraux aux évènements de tempêtes, à des échelles de temps différentes pour une plage située à une latitude moyenne (Biscarrosse, France).
    [Show full text]
  • Management of Coastal Erosion by Creating Large-Scale and Small-Scale Sediment Cells
    COASTAL EROSION CONTROL BASED ON THE CONCEPT OF SEDIMENT CELLS by L. C. van Rijn, www.leovanrijn-sediment.com, March 2013 1. Introduction Nearly all coastal states have to deal with the problem of coastal erosion. Coastal erosion and accretion has always existed and these processes have contributed to the shaping of the present coastlines. However, coastal erosion now is largely intensified due to human activities. Presently, the total coastal area (including houses and buildings) lost in Europe due to marine erosion is estimated to be about 15 km2 per year. The annual cost of mitigation measures is estimated to be about 3 billion euros per year (EUROSION Study, European Commission, 2004), which is not acceptable. Although engineering projects are aimed at solving the erosion problems, it has long been known that these projects can also contribute to creating problems at other nearby locations (side effects). Dramatic examples of side effects are presented by Douglas et al. (The amount of sand removed from America’s beaches by engineering works, Coastal Sediments, 2003), who state that about 1 billion m3 (109 m3) of sand are removed from the beaches of America by engineering works during the past century. The EUROSION study (2004) recommends to deal with coastal erosion by restoring the overall sediment balance on the scale of coastal cells, which are defined as coastal compartments containing the complete cycle of erosion, deposition, sediment sources and sinks and the transport paths involved. Each cell should have sufficient sediment reservoirs (sources of sediment) in the form of buffer zones between the land and the sea and sediment stocks in the nearshore and offshore coastal zones to compensate by natural or artificial processes (nourishment) for sea level rise effects and human-induced erosional effects leading to an overall favourable sediment status.
    [Show full text]
  • A New Technique for Measuring Depth of Disturbance in the Swash Zone
    A NEW TECHNIQUE FOR MEASURING DEPTH OF DISTURBANCE IN THE SWASH ZONE. A Brook 1,2 , C Lemckert 2 1 GHD , Level 13, The Rocket, 203 Robina Town Centre Drive, Robina, Qld 4226, Australia 2 Griffith University, Gold Coast, QLD ABSTRACT Depth of disturbance (DoD), also known as the sediment mixing depth, is a measure of the depth to which the beach face sediment is moved by wave action in the swash zone. By improving our understanding of DoD we can better predict important beach processes - such as natural beach evolution; sediment movement around engineering structures; the design and planning of beach renourishment schemes and sediment-associated pollution transport patterns. To date nearly all studies resolved DoD after a complete tidal cycle. This paper will present a new technique, based on sediment cores, for measuring DoD including conducting detailed analysis both due to a few waves or a complete tidal cycle. The new technique involves freezing sediment cores which can be taken during the tidal cycle. By freezing sediment cores it allows for detailed examination of the DoD and direction of local sand migration. The paper also outlines that, through the use of the Simulating WAves Nearshore (SWAN) model, offshore wave readings from wave buoys can be related to nearshore wave height. Hence, through the dominant relationship of DoD to near shore breaking wave height, estimates of the disturbance to a beach may, in the future, be easily determined without the need to conducted detailed experiments. INTRODUCTION This project was inspired by the inherent need for a better understanding of DoD in the swash zone.
    [Show full text]
  • Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches Tiffany Roberts University of South Florida, [email protected]
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School January 2012 Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches Tiffany Roberts University of South Florida, [email protected] Follow this and additional works at: http://scholarcommons.usf.edu/etd Part of the American Studies Commons, Geology Commons, and the Geomorphology Commons Scholar Commons Citation Roberts, Tiffany, "Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches" (2012). Graduate Theses and Dissertations. http://scholarcommons.usf.edu/etd/4216 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Natural and Anthropogenic Influences on the Morphodynamics of Sandy and Mixed Sand and Gravel Beaches by Tiffany M. Roberts A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Geology College of Arts and Sciences University of South Florida Major Professor: Ping Wang, Ph.D. Bogdan P. Onac, Ph.D. Nathaniel Plant, Ph.D. Jack A. Puleo, Ph.D. Julie D. Rosati, Ph.D. Date of Approval: July 12, 2012 Keywords: barrier island beaches, beach morphodynamics, beach nourishment, longshore sediment transport, cross-shore sediment transport. Copyright © 2012, Tiffany M. Roberts Dedication To my eternally supportive mother, Darlene, my brother and sister, Trey and Amber, my aunt Pat, and the friends who have been by my side through every challenge and triumph.
    [Show full text]
  • Rapid Formation and Degradation of Barrier Spits in Areas with Low Rates of Littoral Drift*
    Marine Geology, 49 (1982) 257-278 257 Elsevier Scientific Publishing Company, Amsterdam- Printed in The Netherlands RAPID FORMATION AND DEGRADATION OF BARRIER SPITS IN AREAS WITH LOW RATES OF LITTORAL DRIFT* D.G. AUBREY and A.G. GAINES, Jr. Woods Hole Oceanographic Institution, Woods Hole, MA 02543 (U.S.A.) (Received February 8, 1982; revised and accepted April 6, 1982) ABSTRACT Aubrey, D.G. and Gaines Jr., A.G., 1982. Rapid formation and degradation of barrier spits in areas with low rates of littoral drift. Mar. Geol., 49: 257-278. A small barrier beach exposed to low-energy waves and a small tidal range (0.7 m) along Nantucket Sound, Mass., has experienced a remarkable growth phase followed by rapid attrition during the past century. In a region of low longshore-transport rates, the barrier spit elongated approximately 1.5 km from 1844 to 1954, developing beyond the baymouth, parallel to the adjacent Nantucket Sound coast. Degradation of the barrier spit was initiated by a succession of hurricanes in 1954 (Carol, Edna and Hazel). A breach opened and stabilized near the bay end of the one kilometer long inlet channel, providing direct access for exchange of baywater with Nantucket Sound, and separating the barrier beach into two nearly equal limbs. The disconnected northeast limb migrated shorewards, beginning near the 1954 inlet and progressing northeastward, filling the relict inlet channel behind it. At present, about ten percent of the northeast limb is subaerial: the rest of the limb has completely filled the former channel and disappeared. The southwest limb of the barrier beach has migrated shoreward, but otherwise has not changed significantly since the breach.
    [Show full text]
  • An Experimental Study of Beach Evolution with an Artificial Seepage
    An Experimental Study of Beach Evolution with an Artificial Seepage Paper: An Experimental Study of Beach Evolution with an Artificial Seepage Changbo Jiang∗,∗∗, Yizhuang Liu∗,BinDeng∗,∗∗,†,YuYao∗,∗∗, and Qiong Huang∗∗∗ ∗School of Hydraulic Engineering, Changsha University of Science and Technology Changsha 410114, P. R. China †Corresponding author, E-mail: [email protected] ∗∗Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, P. R. China ∗∗∗Guangzhou Zhengjian Construction Engineering Design Co., Ltd., Guangzhou 510220, P. R. China [Received April 10, 2016; accepted September 8, 2016] Beach erosion caused by extreme wave events (storm face, which has significantly influenced coastal sediment surges) is reported to occur in many coastal areas. transport [4]. Many researchers have suggested that such Artificially lowering the groundwater table effectively erosion could be induced by exfiltration or higher ground- stabilizes sand beaches in an environmentally friendly water table, while infiltration or lower groundwater table way. Mechanisms affecting beach stabilization remain contributes to onshore sediment transport [5–11]. Other unclear, however, due to the complex interaction be- studies suggest that the groundwater table does not sig- tween waves and coastal seepage. This study discusses nificantly change the beach profile [12–13] possibly be- the effects of coastal seepage on beach profile evolu- cause either infiltration increases the effective bed sedi- tion and bed materials sorting based on laboratory ex- ment weight and thus impedes sediment mobility or infil- periments in which seepage is induced artificially by tration tends to increase bed stress, thus enhancing sedi- a drain pipe at three cross-shore locations on a 1:10 ment mobility.
    [Show full text]
  • Part III-2 Longshore Sediment Transport
    Chapter 2 EM 1110-2-1100 LONGSHORE SEDIMENT TRANSPORT (Part III) 30 April 2002 Table of Contents Page III-2-1. Introduction ............................................................ III-2-1 a. Overview ............................................................. III-2-1 b. Scope of chapter ....................................................... III-2-1 III-2-2. Longshore Sediment Transport Processes ............................... III-2-1 a. Definitions ............................................................ III-2-1 b. Modes of sediment transport .............................................. III-2-3 c. Field identification of longshore sediment transport ........................... III-2-3 (1) Experimental measurement ............................................ III-2-3 (2) Qualitative indicators of longshore transport magnitude and direction ......................................................... III-2-5 (3) Quantitative indicators of longshore transport magnitude ..................... III-2-6 (4) Longshore sediment transport estimations in the United States ................. III-2-7 III-2-3. Predicting Potential Longshore Sediment Transport ...................... III-2-7 a. Energy flux method .................................................... III-2-10 (1) Historical background ............................................... III-2-10 (2) Description ........................................................ III-2-10 (3) Variation of K with median grain size................................... III-2-13 (4) Variation of K with
    [Show full text]
  • Beach Memory and Ensemble Prediction of Shoreline Evolution Near a Groyne
    Coastal Engineering 86 (2014) 77–87 Contents lists available at ScienceDirect Coastal Engineering journal homepage: www.elsevier.com/locate/coastaleng Beach memory and ensemble prediction of shoreline evolution near a groyne Dominic E. Reeve a,⁎,AdriánPedrozo-Acuñab, Mark Spivack c a College of Engineering, Swansea University, Wales, UK b Instituto de Ingeniería Universidad Nacional Autónoma de México, México D.F., Mexico c Department of Applied Mathematics and Theoretical Physics, University of Cambridge, UK article info abstract Article history: In this paper we address the question of estimating the average position of a beach and its inherent variability Received 13 May 2013 about this mean. It is demonstrated how, even in a much simplified situation, the ensemble average of beach Received in revised form 17 November 2013 plan shape involves cross-correlation of the beach position and wave conditions. This renders the governing Accepted 22 November 2013 equations inimical to analytical treatment. A new analytical expression for the mean beach plan shape and its variation are derived for the case of a single groyne exposed to waves varying in direction only. This demonstrates Keywords: that ‘beach memory’ is directly related to the autocorrelation of wave direction. For more general conditions a Ensemble modelling Wave chronology semi-analytical expression for the ensemble average of the shoreline position is derived. This solution is estimated Monte-Carlo simulation with site specific wave conditions using Monte Carlo simulations. The characteristics of the solution are investigated Beach memory and it is demonstrated that, for this case at least, the terms involving the wave direction are virtually uncorrelated Shoreline prediction with the terms that do not.
    [Show full text]
  • The Relationship Between Wave Action and Beach Profile Characteristics
    CHAPTER 14 THE RELATIONSHIP BETWEEN WAVE ACTION AND BEACH PROFILE CHARACTERISTICS P. H. Kemp Department of GivH Engineering. University College London, England. ABSTRACT. The rational design of coast protection works requires a knowledge of the behaviour of the beach under natural conditions. The understanding of the relationship between the waves acting on the beach and the characteristics of the beach profile produced, is thus a necessary preliminary to the analysis of the causes of beach erosion and the evaluation of the effect of projected remedial measures. The present paper describes the results of a series of prelimin- ary hydraulic model experiments carried out by the author prior to a model study of the behaviour of groynes in stabilising beaches. Most of the beach materials used represented coarse sand or shingle in nature. The results demonstrate the fundamental importance of the "phase- difference" in terms of wave period between the break-point and the limit of uprush, in relation to flow conditions, cusp formation, and the change from "step" to "bar" type profiles. Within the limits of the experiments an expression connecting the breaker height, beach profile length, and grain diameter is developed, and its implications examined in relation to beach slope, and to the previous "wave steepness" criterion for the change from step to bar type profiles. Observations are included on the rate of recession of a shore- line due to the onset of more severe wave conditions. INTRODUCTION. BEACH CHANGES. Changes in the coastline may be classified as:- (1) Progressive changes resulting in prograding or recession of the shoreline over a long period of time.
    [Show full text]
  • Pocket Beach Hydrodynamics: the Example of Four Macrotidal Beaches, Brittany, France
    Marine Geology 266 (2009) 1–17 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margeo Pocket beach hydrodynamics: The example of four macrotidal beaches, Brittany, France A. Dehouck a,⁎, H. Dupuis b, N. Sénéchal b a Géomer, UMR 6554 LETG CNRS, Université de Bretagne Occidentale, Institut Universitaire Européen de la Mer, Technopôle Brest Iroise, 29280 Plouzané, France b UMR 5805 EPOC CNRS, Université de Bordeaux, avenue des facultés, 33405 Talence cedex, France article info abstract Article history: During several field experiments, measurements of waves and currents as well as topographic surveys were Received 24 February 2009 conducted on four morphologically-contrasted macrotidal beaches along the rocky Iroise coastline in Brittany Received in revised form 6 July 2009 (France). These datasets provide new insight on the hydrodynamics of pocket beaches, which are rather poorly Accepted 10 July 2009 documented compared to wide and open beaches. The results notably highlight a cross-shore gradient in the Available online 18 July 2009 magnitude of tidal currents which are relatively strong offshore of the beaches but are insignificant inshore. Communicated by J.T. Wells Despite the macrotidal setting, the hydrodynamics of these beaches are thus totally wave-driven in the intertidal zone. The crucial role of wind forcing is emphasized for both moderately and highly protected beaches, as this Keywords: mechanism drives mean currents two to three times stronger than those due to more energetic swells when beach morphodynamics winds blow nearly parallel to the shoreline. Moreover, the mean alongshore current appears to be essentially embayed beach wind-driven, wind waves being superimposed on shore-normal oceanic swells during storms, and variations in beach cusps their magnitude being coherent with those of the wind direction.
    [Show full text]
  • Mathematical Model of Groynes on Shingle Beaches
    HR Wallingford Mathematical Model of Groynes on Shingle Beaches A H Brampton BSc PhD D G Goldberg BA Report SR 276 November 1991 Address:Hydraulics Research Ltd, wallingford,oxfordshire oxl0 gBA,United Kingdom. Telephone:0491 35381 Intemarional + 44 49135381 relex: g4gsszHRSwALG. Facstunile:049132233Intemarional + M 49132233 Registeredin EngtandNo. 1622174 This report describes an investigation carried out by HR Wallingford under contract CSA 1437, 'rMathematical- Model of Groynes on Shingle Beaches", funded by the Ministry of Agri-culture, Fisheries and Food. The departmental nominated. officer for this contract was Mr A J Allison. The company's nominated. project officer was Dr S W Huntington. This report is published on behalf of the Ministry of Agriculture, Fisheries and Food, but the opinions e>rpressed are not necessarily those of the Ministry. @ Crown Copyright 1991 Published by permission of the Controller of Her Majesty's Stationery Office Mathematical model of groSmes on shingle beaches A H Brampton BSc PhD D G Goldberg BA Report SR 276 November 1991 ABSTRACT This report describes the development of a mathematical model of a shingle beach with gro5mes. The development of the beach plan shape is calculated given infornation on its initial position and information on wave conditions just offshore. Different groyne profiles and spacings can be specified, so that alternative gro5me systems can be investigated. Ttre model includes a method for dealing with varying water levels as the result of tidal rise and fall. CONTENTS Page 1. INTRODUCTION I 2. SCOPEOF THE UODEL 3 2.t Model resolution and input conditions 3 2.2 Sediment transport mechanisms 6 2.3 Vertical distribution of sediment transport q 2.4 Wave transformation modelling L0 3.
    [Show full text]
  • Lecture 12: Coasts
    Ediz Hook, Port Angeles ESCI 321 announcements • Problem set 2 due tonight at midnight • Exam 2 in one week • We will have a major review session next Thursday. Come with questions. • Study guide posted. Bring to class on Thursday Coasts, beaches and estuaries I. Coast formation II. Beaches: Rivers of sand III. Estuaries http://www.nps.gov/olym/naturescience/damremovalblog.htm 1 Processes determining coastal morphology and formation Beach morphology Plate tectonics Sea level changes (eustatic and relative sea level change) Glaciers Weathering Wave action and storms Maine N.C. General scheme of coastline development (primary → secondary) Seasonal changes in beach morphology Longshore sediment transport How do waves affect beaches? (Beach movie) 2 Tombolo on the shore of Lake Erie, Erie, Pennsylvania Formation of rip currents and beach cusps Sediment composing barrier Islands along the east coast of the U.S. is continuously eroding and depositing toward the continent and toward the south. Swash on beach cusps at Propriano, Corsica. (Photo: Sogreah, France) Rip currents on a New Zealand beach 3 Dune Ridge Beach Open Ocean Puget Sound coastlines Lagoon Marsh Flat Lagoonal Peat Common types of shorelines in Puget Sound Natural shoreline with development •Sand and gravel •Sandy beach/dunes •Sediment-starved beach •Mudflats •Deltas •Beach w/ bulkheads 4 Shoreline with bulkhead Effects of beach armoring on amphipod habitat, Paihia, New Zealand Forage fish spawning grounds in Bellingham Bay • Surf smelt spawn in upper intertidal zone • In Bellingham
    [Show full text]