DOCSLIB.ORG

U N C O R R Ec Ted Pr O

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
U N C O R R Ec Ted Pr O SED 773 Dispatch: 1.2.06 Journal: SED CE: Hari Journal Name Manuscript No. B Author Received: No. of pages: 18 PE: Revathi Sedimentology (2006) 1–18 doi: 10.1111/j.1365-3091.2006.00773.x Sedimentology and stratigraphy of a transgressive, muddy gravel beach: waterside beach, Bay of Fundy, Canada F SHAHIN E. DASHTGARD*, MURRAY K. GINGRAS* and KARL E. BUTLER *Department of Earth and Atmospheric Sciences, 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB, Canada T6E 2G3 (E-mail: [email protected]) O Department of Geology, University of New Brunswick, PO Box 4400, Fredericton, NB, Canada E3B 5A3 ABSTRACT O Sediments exposed at low tide on the transgressive, hypertidal (>6 m tidal range) Waterside Beach, New Brunswick, Canada permit the scrutinyR of sedimentary structures and textures that develop at water depths equivalent to the upper and lower shoreface. Waterside Beach sediments are grouped into eleven sedimentologically distinct deposits that represent threeP depositional environments: (1) sandy foreshore and shoreface; (2) tidal-creek braid-plain and delta; and, (3) wave-formed gravel and sand bars, and associated deposits. The sandy foreshore and shoreface depositional environment encompasses the backshore; moderately dipping beachface; and, a shallowlyD seaward-dipping terrace of sandy middle and lower intertidal, and muddy sub-tidal sediments. Intertidal sediments reworked and deposited by tidal creeks comprise the tidal-creek braid plain and delta. Wave-formedE sand and gravel bars and associated deposits include: sediment sourced from low-amplitude, unstable sand bars; gravel deposited from large (up to 5Æ5 m high, 800 m long), landward-migrating gravel bars; and, zones ofT mud deposition developed on the landward side of the gravel bars. The relationship between the gravel bars and mud deposits, and between mud-laden sea water and beach gravels provides mechanisms for the depositionC of mud beds, and muddy clast- and matrix-supported conglomerates in ancient conglomeratic successions. Idealized sections are presentedE as analogues for ancient conglomerates deposited in transgressive systems. Where tidal creeks do not influence sedimentation on the beach, the preserved sequence consists of a gravel lag overlain by increasingly finer-grainedR shoreface sediments. Conversely, where tidal creeks debouch onto the beach, erosion of the underlying salt marsh results in deposition of a thicker, more complex beach succession. The thickness of this packageR is controlled by tidal range, sedimentation rate, and rate of transgression. The tidal-creek influenced succession comprises repeated sequences of: a thin mud bed overlain by muddy conglomerate, sandy conglomerate,O a coarse lag, and capped by trough cross-bedded sand and gravel. Keywords Beach, conglomerate, macrotidal, mud and gravel, muddy con- glomerate, sedimentology,C stratigraphy, transgressive. INTRODUCTIONN logical and stratigraphic relationships on modern beaches aids in predicting the extent, thickness, Studies of modern, transgressive gravel beaches and morphology of conglomerates in the sub- provide importantU information regarding facies surface. Waterside Beach is a transgressive, relationships and organization of ancient conglo- muddy gravel beach in the hypertidal Bay of merates. In particular, determining sedimento- Fundy. Because of the area’s extreme tidal range Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists 1 2 S.E. Dashtgard, M.K. Gingras and K.E. Butler (up to 12 m), foreshore (and shoreface equivalent) foreshore sediments (Clifton, 1981; Massari & sediments are exceptionally well exposed at Parea, 1988). spring low tide. This provides an opportunity to Waterside Beach, New Brunswick, Canada is a assess the sedimentological characteristics of transgressive, muddy gravel beach in the hyper- conglomerates deposited at water depths equival- tidal Bay of Fundy. It is considered that the ent to the upper and lower shoreface (i.e. depos- structures and morphology of the intertidalF ited because of shoaling, breaker, surf, and swash deposits partly result from depositional processes processes). In this paper: (1) sedimentologically (shoaling, breaker, surf, and swash zone pro- distinct deposits are reported; (2) mechanisms for cesses) and water depths equivalent toO the upper depositing mud beds and muddy conglomerates and lower shoreface. Examination of these mod- on gravel beaches are described; and, (3) inferred ern deposits, therefore, provides insights into the stratigraphic successions of transgressive gravel facies and facies relationshipsO of hydraulically beaches are proposed. reworked shoreface conglomerates. Sedimentological descriptions of modern, wave-dominated gravel foreshores and back- Study area R shores are common in geological literature. The original model presented by Bluck (1967) recog- Waterside Beach is located on the New Bruns- nized distinct, shore-parallel zones based on wick coastline of ChignectoP Bay (Fig. 1). Oriented clast-shape selection. This shore-normal zonation northwest–southeast the beach is perpendicular is observed from gravel beaches around the world to the dominant southwest winds (Amos & (Carr, 1969; Carr et al., 1970; Maejima, 1982; Hart Asprey, 1979). During winter cyclones (mainly & Plint, 1989; Postma & Nemec, 1990; Bartholoma¨ November through January) it experiences peak et al., 1998; Bluck, 1999) and may be considered significant waveD heights of 3 m and wave periods typical of high-energy, wave-dominated shore- of 10 sec (Amos et al., 1991). Overall, most lines with a limited fluvial- or marine-sediment significantE waves heights (79%) are below supply. The above model, however, is limited 1Æ25 m with periods of 7 sec or less (Amos et al., to a narrow (average 100–200 m wide) beach- 1991). Waterside Beach experiences a mean tidal normal zone that includes the steeply dipping rangeT of 9 m. Vertical tidal range varies from 6 m beachface (foreshore), berm, and backshore during neap tides to 12 m during spring tides (Bluck, 1967; Carr et al., 1970; Kirk, 1980; Mae- resulting in exposure of up to 1200 m of intertidal jima, 1982; Postma & Nemec, 1990). Modern Czone at low tide. Additionally, up to 650 m of nearshore (shoreface) and more basinal conglo- beach sediments occur sub-tidally (Fig. 2). The merate facies have been described (Hart & Plint, toe of the beach is demarcated by a step that is 1989), but are generally poorly understood.E locally steep (1°), but generally weakly defined. Shoreface conglomerate models are therefore, On the landward edge, backshore and beachface mainly derived from outcrop and core (Clifton, deposits abut either salt marsh or bedrock cliffs 1981, 1988; Massari & Parea, 1988; HartR & Plint, (Fig. 1C). 1989, 2003; Caddell & Moslow, 2004; Zonneveld At the northwest end of the beach, sand with & Moslow, 2004). As a result, most modern minor gravel is the dominant sediment; whereas, depositional models for conglomeratesR are a gravel is present near the mouth of Long Marsh composite of modern foreshore deposits, and Creek (Figs 1B and 2). A maintained dike backs ancient shoreface and more basinal deposits the beach in the southeast (Fig. 1B and C). The (Bourgeois & Leithold, 1984). O dike has significantly hindered transgression, yet Shoreface conglomerates are broadly sub- does not appear to interrupt beach sedimentation divided as transgressive and regressive (Wescott patterns in the intertidal and sub-tidal zones & Ethridge, 1982; Bourgeois & Leithold, 1984; (Fig. 2). Postma & Nemec, 1990).C Transgressive conglom- erate successions encountered in the rock record Methods tend to lack backshore and foreshore deposits as a result of erosion duringN transgression (Bourgeois Fieldwork on Waterside Beach was undertaken in & Leithold, 1984). Regressive (progradational) 2003 and 2004. Beach-normal and beach-parallel gravel beaches tend to be characterized by transects were conducted to establish beach repeating sequencesU of coarsening-upward con- zonation and morphology. Line-and-level meas- glomerates with internal erosional surfaces (Bour- urements were used to document changes in geois & Leithold, 1984), and by the preservation of slope and to establish major changes in morphol- Ó 2006 The Authors. Journal compilation Ó 2006 International Association of Sedimentologists, Sedimentology, 1–18 Sedimentology, stratigraphy of muddy gravel beaches 3 ′ ′ A 65 63 trenches dug mainly perpendicular to deposi- P.E.I. Moncton tional strike. Box cores were collected at most NEW 46′ stations for X-ray imaging. BRUNSWICK High-resolution, single-channel seismic pro- Study Area Chignecto Bay files were acquired in 2003 and 2004. TheseF Saint John surveys were used to map out the toe of the beach NOVA SCOTIA (Fig. 2), but otherwise are not presented in this U.S.A. paper. In 2005, a grab-sampling program was BAY OF FUNDY Halifax undertaken to sample sub-tidal beachO and off- shore sediments. Samples collected during this 0 50 100 ATLANTIC OCEAN program are incorporated into the grain-size data ′ 44 44′ N kilometers and are used to map out the horizontal distribu- ′ ′ ′ 67 W 65 63 O tion of sediments in the sub-tidal zone (Fig. 2). B Grain-size distribution on Waterside Beach was determined using one of three techniques: (1) grid Dennis Bea 915 R Long Marsh sampling, (2) bulk-sample dry sieving, and (3) X- Waterside Bea Creek ch ray absorption. (1) Grid sampling (Wolman, 1954; Rice & Church, 1996; Hoey, 2004) was employed ch P for deposits with
Load more

Recommended publications
  • The Strait of Anian and British Northwest America: Cook's Third Voyage in Perspective*
    The Strait of Anian and British Northwest America: Cook's Third Voyage in Perspective* JOHNNORRIS For local patriots of British Columbia, Captain Cook's third voyage is unsatisfactory. His stay at Nootka was so brief, his exploration of the coast so perfunctory, and his preoccupation with Alaska so much to be deplored. We are driven, in asking the reasons for these solecisms, to examine his instructions from the Admiralty for the third voyage. Alas, they hardly mention the coast of Northwest America between 45 ° and 65 ° North. Did their Lordships of the Admiralty slip up? Was Cook, that supreme professional who had had a hand in drawing up his own instructions, at less than his expert best? Did Palinurus nod at the helm? Cook's landing at Nootka was the result of his instructions "to put into the first convenient Port to recruit your Wood and Water and procure Refreshments . .Jîl But the prolongation of his stay to four weeks (29 March to 26 April 1778) was traceable to the bad fitting-out of his ships by the Navy Board, which resulted in the rotten foretop and mizzen masts of the Resolution having to be replaced after the strain of the spring gales of the North Pacific. Further, the avoidance of virtually all the rest of the British Columbia coast was in accordance with those instructions, since Cook was ordered to: ... proceed Northward along the Coast as far as the Latitude of 65 °, or farther, if you are not obstructed by Lands or Ice; taking care not to lose any time in exploring Rivers or Inlets, or upon any other account, until you get into the before-mentioned latitude of 65 °...
    [Show full text]
  • “Major World Deltas: a Perspective from Space
    “MAJOR WORLD DELTAS: A PERSPECTIVE FROM SPACE” James M. Coleman Oscar K. Huh Coastal Studies Institute Louisiana State University Baton Rouge, LA TABLE OF CONTENTS Page INTRODUCTION……………………………………………………………………4 Major River Systems and their Subsystem Components……………………..4 Drainage Basin………………………………………………………..7 Alluvial Valley………………………………………………………15 Receiving Basin……………………………………………………..15 Delta Plain…………………………………………………………...22 Deltaic Process-Form Variability: A Brief Summary……………………….29 The Drainage Basin and The Discharge Regime…………………....29 Nearshore Marine Energy Climate And Discharge Effectiveness…..29 River-Mouth Process-Form Variability……………………………..36 DELTA DESCRIPTIONS…………………………………………………………..37 Amu Darya River System………………………………………………...…45 Baram River System………………………………………………………...49 Burdekin River System……………………………………………………...53 Chao Phraya River System……………………………………….…………57 Colville River System………………………………………………….……62 Danube River System…………………………………………………….…66 Dneiper River System………………………………………………….……74 Ebro River System……………………………………………………..……77 Fly River System………………………………………………………...…..79 Ganges-Brahmaputra River System…………………………………………83 Girjalva River System…………………………………………………….…91 Krishna-Godavari River System…………………………………………… 94 Huang He River System………………………………………………..……99 Indus River System…………………………………………………………105 Irrawaddy River System……………………………………………………113 Klang River System……………………………………………………...…117 Lena River System……………………………………………………….…121 MacKenzie River System………………………………………………..…126 Magdelena River System……………………………………………..….…130
    [Show full text]
  • A Geomorphic Classification System
    A Geomorphic Classification System U.S.D.A. Forest Service Geomorphology Working Group Haskins, Donald M.1, Correll, Cynthia S.2, Foster, Richard A.3, Chatoian, John M.4, Fincher, James M.5, Strenger, Steven 6, Keys, James E. Jr.7, Maxwell, James R.8 and King, Thomas 9 February 1998 Version 1.4 1 Forest Geologist, Shasta-Trinity National Forests, Pacific Southwest Region, Redding, CA; 2 Soil Scientist, Range Staff, Washington Office, Prineville, OR; 3 Area Soil Scientist, Chatham Area, Tongass National Forest, Alaska Region, Sitka, AK; 4 Regional Geologist, Pacific Southwest Region, San Francisco, CA; 5 Integrated Resource Inventory Program Manager, Alaska Region, Juneau, AK; 6 Supervisory Soil Scientist, Southwest Region, Albuquerque, NM; 7 Interagency Liaison for Washington Office ECOMAP Group, Southern Region, Atlanta, GA; 8 Water Program Leader, Rocky Mountain Region, Golden, CO; and 9 Geology Program Manager, Washington Office, Washington, DC. A Geomorphic Classification System 1 Table of Contents Abstract .......................................................................................................................................... 5 I. INTRODUCTION................................................................................................................. 6 History of Classification Efforts in the Forest Service ............................................................... 6 History of Development .............................................................................................................. 7 Goals
    [Show full text]
  • The Colorado River Damming Impact on the Shrimp Fishery in the Upper
    FRONTERA NORTE VOL. 33, ART. 9, 2021 https://doi.org/10.33679/rfn.v1i1.2137 The Colorado River Damming Impact on the Shrimp Fishery in the Upper Gulf of California, Mexico El impacto del represamiento del Río Colorado en la pesquería del camarón en el Alto Golfo de California, México Manuel Salvador Galindo Bect,1 Carlos Israel Vázquez León,2 & David Aguilar Montero3 ABSTRACT The objective oF this work is to demonstrate the relationship among the Colorado River Flows and volumes of shrimp caught in the Upper GulF of CaliFornia (AGC). A correlation analysis was applied to historical series of data about landed shrimp catch, fishing effort and flow from the Colorado River towards the gulf. Dependence, proportionality, and linear relationship indicators were obtained. The main results showed that the interannual captures were lower in periods without water input From the river and higher with the water inputs to the estuary. In addition, the results showed that the contributions of nutrients carried in the river water to the estuary could increase the Carbon Fixation. This study is important because it contributes to the discussion and strengthens the Fact that this river is important in the environmental and fishing dynamics in the AGC. Keywords: 1. Colorado River, 2. Fisheries, 3. shrimp, 4. damming, 5. Upper GulF oF CaliFornia. RESUMEN El objetivo de este trabajo es demostrar la relación entre los Flujos del Río Colorado y los volúmenes de camarón capturados en el Alto GolFo de CaliFornia (AGC). Se aplicó un análisis de correlación a series históricas de datos de captura del desembarque de camarón, el esfuerzo pesquero y el flujo del Río Colorado hacia el Delta.
    [Show full text]
  • The Second Twenty Years, 1971-1991
    Northwestern Michigan College The Second IVvenfy Years 1971 -1991 Al Shumsky Assisted by Carole Marlatt NORTHWESTERN MICHIGAN COLLEGE The Second Twenty Years 1971-1991 A1 Shumsky Assisted by Carole Marlatt February 1994 ACKNOWLEDGMENTS Thanks are due many people who helped with this project. First to the two people without whom it could not have been done: Tim Quinn and Carole Marlatt. Tim initiated the project and supported it with released time, and with no directions whatsoever beyond "Have a good time!" Carole not only prepared the manuscript, assembled the rosters in the appendix, chose the pictures, and both provided her own and edited my memories; she also is the one who recorded the Board minutes for these twenty years and then indexed them and preserved the hard copy so it was available to this amateur historian. (She, in fact, is the one to go to if you want to know what really went on during these years.) Thanks are also due these many others who graciously provided information or corroborated memories: Bob Buttleman, Doug Campbell, Becky Chartier, Jan Gasnik, Kathleen Guy, Chet Janik, Bill King, George Kuhn, Keith MacPhee, Nancy McArthur, Shelley Merrill, Dick Minor, Shirley Okerstrom, Barbara Raehl, Joe Rogers, PatSalathiel, Bill Shaw, Don Shikoski, Chuck Shreve, Robbie Teahen, Bob Warner, and Steve Westphal. Recognition is also due the hundreds of people—Board members, faculty and staff—whose names do not appear in this account, but who in fact constituted the College. Without them, there would be no history to write. I apologize to all whose contributions have not been specifically mentioned.
    [Show full text]
  • Impacts of Sand Mining on Beaches in Suriname
    Impacts of sand mining on beaches in Suriname Braamspunt beach, February 2016 Edward J. Anthony Consultant in Geomorphology and Shoreline Management June, 2016. Background p. 3 Abstract p. 4 Summary of recommendations p. 5 Part 1. The environment, context and formation of sandy beaches in Suriname p. 6 1.1. Introduction p. 7 1.2. The Guianas mud-bank system p. 11 1.3. Cheniers and chenier beaches: natural wave-energy buffers and ecosystems p. 15 1.4. Bank and inter-bank phases, and inter-bank chenier development p. 17 1.5. River mouths and chenier development p. 19 1.6. The Suriname Coastal Plain and long-term chenier development p. 22 Part 2. Recent shoreline changes in Suriname: general morphodynamics, methodology and results for Braamspunt beach p. 27 2.1. Chenier morphodynamics – cross-shore and longshore processes p. 28 2.1. The Maroni and Surniname river-mouth contexts and Braamspunt beach p. 33 2.2. Methodology: recent shoreline changes and evolution of Braamspunt beach p. 35 2.2.1. Mesoscale (multi-decadal changes) p. 35 2.2.2. Field surveys of the morphology and dynamics of Braamspunt beach p. 38 2.3. Recent bank and inter-bank phases on the Suriname coast p. 43 2.3.1. The Maroni-Suriname sector p. 44 2.3.2. The Suriname-Coppename sector p. 44 2.3.3. The Coppename-Corantijn sector p. 45 2.4. Morphodynamics of Braamspunt beach p. 45 2.4.1. Offshore and nearshore hydrodynamic conditions p. 45 2.4.2. Grain-size and sedimentology of Braamspunt beach p.
    [Show full text]
  • Physiography
    .1· , Atlantic Continental Shelf and Slope ~. of the United States ·- •t.,........_,C',...,.~~~""' 11:'·~~. '"''"' ~.~..-.. ......-.,· ....... ~ ·-,}........ ·. '~':7'n:.~~-... "" • '•ilfl::.t,l.>.o;r,~... ,, ~· ·-·· ·-. - '··~~ ..~-~'·· ··_ -·· ·~~--~----1 .., Physiography GEOLOGICAL SURVEY PROFESSIONAL PAPER 529-C Atlantic Continental · Shelf and Slope of The United States- Physiography By ELAZAR UCHUPI GEOLOGICAL SURVEY PROFESSIONAL PAPER 529-C Description of the submarine physiography of the continental margin between Nova Scotia and the Florida Keys UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1968 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director ~ : . For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Page Abstract __________________________________________ _ C1 Continental margin-Continued Introduction ______________________________________ _ 1 Intermediate provinces _________________________ _ C17 General statement _____________________________ _ 1 Blake Plateau_·____________________________ _ 17 Acknowledgments ______ -.- ______________________ _ 3 Straits of Florida __________________________ _ 19 Continental margin ________________________________ _ 3 Continental slope ______________________________ _ 21 General setting________________________________ _ 3 Provinces seaward of the continental slope ________ _ 27 Continental shelf ______________________________ _ 3 Continental rise ___________________________
    [Show full text]
  • River Channel Bars and Dunes- Theory of Kinematic Waves
    River Channel Bars and Dunes- Theory of Kinematic Waves GEOLOGICAL SURVEY PROFESSIONAL PAPER 422-L River Channel Bars and Dunes- Theory of Kinematic Waves By WALTER B. LANGBEIN and LUNA B. LEOPOLD PHYSIOGRAPHIC AND HYDRAULIC STUDIES OF RIVERS GEOLOGICAL SURVEY PROFESSIONAL PAPER 422-L UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1968 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 20 cents (paper cover) CONTENTS Page Page Abstract_________________________________________ LI Effect of rock spacing on rock movement in an ephemeral Introduction.______________________________________ 1 stream._________________________________________ L9 Flux-concentration relations________________________ 2 Waves in bed form________________________________ 12 Relation of particle speed to spacing a flume experi- General features________________________________ 12 ment______-_____-____-____-_-____________--____. 4 Kinematic properties_._______-._________________ 15 Transport of sand in pipes and flumes_________________ 5 Gravel bars____________________________________ 17 Flux-concentration curve for pipes________________ 6 Summary__________________________________________ 19 Flume transport of sand_________________________ 7 References________________.______________________ 19 ILLUSTRATIONS Page FIGURE 1. Flux-concentration curve for traffic___________________________________________________-_-_-__-___-
    [Show full text]
  • Mission: History Studiorum Historiam Praemium Est
    See story on page 5 Naval Order of the United States – San Francisco Co m m a n d e r y Mission: History Studiorum Historiam Praemium Est Volume 1, Issue 9 HHHHHH 4 October 1999 1944: With the World’s Eyes on Europe, U.S. Fights History’s Largest Sea Battle This Month’s Contents Ambush at Palawan Passage Page 7 Leyte Gulf Actions See Destruction Sibuyan Sea Air Attacks 7 Loss of Princeton 13 Battle of Surigao Strait 2 Of Japanese Navy as Fighting Force Main Event off Samar 3 In October 1944, the attention of American newspapers and radio was firmly fo- Halsey Abandons Kinkaid 3 Leyte Charts 2 cused on Europe, particularly on the German fortress at Metz, in northeast France. Battle of Trafalgar 5 General George S. Patton’s seemingly invincible Third Army had bounced off Metz Trafalgar Chart 16 without leaving a dent. Americans had grown to expect great things from Patton, so they sat by their radios and read the newspapers waiting for Metz to fall. In this vacuum of news from the Pacific, the greatest of all naval battles was fought. The Japanese Navy rolled the dice with everything they had on the line. Two hundred seventy-six war- ships ranging in size from destroyer to the world’s largest battleships took part in the Battle of Leyte Gulf. When it was over, the Jap navy had ceased to exist as a fighting force. There were no replacements in the pipeline and, in fact, there had never been a pipeline to begin with.
    [Show full text]
  • Understanding Sediment Bypassing Processes Through Analysis of High- Frequency Observations of Ameland Inlet, the Netherlands T ⁎ Edwin P.L
    Marine Geology 415 (2019) 105956 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margo Understanding sediment bypassing processes through analysis of high- frequency observations of Ameland Inlet, the Netherlands T ⁎ Edwin P.L. Eliasa, , Ad J.F. Van der Spekb,c, Stuart G. Pearsonb,d, Jelmer Cleveringae a Deltares USA, 8601 Georgia Ave, Silver Spring, MD 20910, USA b Deltares, P.O. Box 177, 2600 MH Delft, the Netherlands c Faculty of Geosciences, Utrecht University, P.O. Box 80115, 3508 TC Utrecht, the Netherlands d Faculty of Civil Engineering and Geosciences, Delft University of Technology, PO Box 5048, 2600GA Delft, the Netherlands e Arcadis Nederland B.V., P.O. Box 137, 8000 AC Zwolle, the Netherlands ARTICLE INFO ABSTRACT Editor: Edward Anthony Ameland inlet is centrally located in the chain of West Frisian Islands (the Netherlands). A globally unique Keywords: dataset of detailed bathymetric charts starting in the early 19th century, and high-resolution digital data since Ameland Inlet 1986 allows for detailed investigations of the ebb-tidal delta morphodynamics and sediment bypassing over a The Netherlands wide range of scales. The ebb-tidal delta exerts a large influence on the updrift and downdrift shorelines, leading Coastal morphodynamics to periodic growth and decay (net erosion) of the updrift (Terschelling) island tip, while sequences of sediment Ebb-tidal delta bypassing result in shoal attachment to the downdrift coastline of Ameland. Distinct differences in location, Sediment bypassing shape and volume of the attachment shoals result from differences in sediment bypassing, which can be driven Tidal inlet by morphodynamic interactions at the large scale of the inlet system (O(10 km)), and through interactions that Wadden Sea originate at the smallest scale of individual shoal instabilities (O(0.1 km)).
    [Show full text]
  • Europe's Coastal Erosion in a Changing Climate
    Europe’s coastal erosion in a changing climate www.climatechangepost.com Latest update: 19 March 2019 Coastal erosion in Europe Overview All European coastal states are to some extent affected by coastal erosion. About twenty thousand kilometres of coasts is eroding, of which three-quarters is actively retreating, and a quarter is artificially stabilised. Coastal erosion results in • loss of land with economical value • destruction of natural sea defences (usually a dune system) as a result of storm events, which may result in flooding of the hinterland • undermining of artificial sea defences as a result of chronic sediment shortage The cost of coastal erosion (coastline protection against the risk of erosion and flooding) has been estimated to average 5,400 million euro per year between 1990 and 2020. Source: Salman et al. (2004); Pranzini and Williams (2013) 3/4 retreating 20,000 km 5,400 million euro/year 1/4 stabilised www.climatechangepost.com Coastal erosion patterns in Europe Overview Status of coastline (EUROSION 2004): Aggradation Mixed aggradation/erosion Erosion Stable Mostly stable Modified after EUROSION map (European Environment Agency, downloaded February 2019) www.climatechangepost.com Coastal erosion patterns in Europe Overview Status of coastline (EUROSION 2004): Aggradation Mixed aggradation/erosion Erosion Stable Mostly stable Part of the national coastline ..% that is eroding according to Pranzini and Williams (2013) 24% 27% 41% 20% 17% 13% 66% 30% 71% 21% 36% 29% 69% 30% Modified after EUROSION map (European Environment Agency, downloaded February 2019) www.climatechangepost.com Overview Beach erosion: Upper limit erosion rate is generally about 2 metres per year, with exceptions up to 10 metres.
    [Show full text]
  • Landslide-Induced River Channel Avulsions in Mountain Catchments of Southwest New Zealand
    Geomorphology 63 (2004) 57–80 www.elsevier.com/locate/geomorph Landslide-induced river channel avulsions in mountain catchments of southwest New Zealand Oliver Korup* School of Earth Sciences, Victoria University of Wellington, P.O. Box 600, New Zealand Received 3 April 2003; received in revised form 19 March 2004; accepted 22 March 2004 Available online 20 May 2004 Abstract Pulsed or chronic supply of landslide debris to valley floors has historically caused substantial aggradation and channel instability in several alpine catchments of SW New Zealand. In this regional investigation of landslide impacts on river morphology, three types of landslide-induced channel avulsion are discerned: (i) upstream/backwater avulsions, (ii) contact avulsions, and (iii) downstream/loading avulsions. The basis for this qualitative geomorphic process-response framework is the principal direction of fluvial response with respect to its position relative to the causative landslide emplacement site. Downstream avulsions have the highest damage potential to land use and infrastructure on unconfined mountain-fringe alluvial fans. In the wake of such events, catastrophic aggradation may obliterate up to several km2 of mature floodplain forests by burial under several metres within a few decades. Estimates of mean aggradation rates are high (<220 mm yearÀ1) and exceed long-term (103 year) trends of fluvial degradation by an order of magnitude. Future potential avulsion routeways may be detected by geomorphic mapping of abandoned channels, which are preferentially reactivated in the wake of landslide-induced sediment waves. D 2004 Elsevier B.V. All rights reserved. Keywords: Avulsion; River channel; Landslide; Channel–hillslope coupling; Aggradation 1. Introduction sediment loads maintained over years or decades.
    [Show full text]