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FIELDWORK AT TEIGNMOUTH, UK

FIELDWORK AT TEIGNMOUTH, UK. Overview of the characteristics of the May 2003 Campaign (Phase II 12/05/03 – 30/05/03). CONTENTS. Site characteristics Objectives of the field campaign Coastal State Indicators & field data needs

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FIELDWORK AT TEIGNMOUTH, UK

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  1. FIELDWORK AT TEIGNMOUTH, UK Overview of the characteristics of the May 2003 Campaign (Phase II 12/05/03 – 30/05/03)

  2. CONTENTS • Site characteristics • Objectives of the field campaign • Coastal State Indicators & field data needs • Comparison of data collected (Phase I vs Phase II) (how, where, main variables, main results) • Morphology measurements • Shoreline surveying • ADCP measurements (currents and waves). • SLOT data (waves, currents, and sediment transport) • Summary

  3. Sediment movement SITE CHARACTERISTICS • Complex system of multiple bars • Long-term cycle (5-8 years) • Sandbar movement cause: • Navigational problems • Recreational hazards • Governs sediment budget on the beach (affecting the structural stability of seawall) slot

  4. OBJECTIVES • Provide “ground truth” for validation and development of video-derived CSIs • Provide in-depth understanding of the morphological cycle (video) and the associated (short term) sediment transport processes (SLOT). • Show data availability and methods of collection to partners

  5. Coastal Management Issues Video-derived CSIs Field data Video-derived CSIs Field data needs • Breaking wave patterns (2D) • Intertidal mapping (3D) • Subtidal mapping (3D) • Bathymetric surveys • Surface currents • Beach morphology • Location of channel markers • Shoreline surveying • Location of dredging • ADCP (currents) • Directional wave spectra • ADCP (directional waves) • System classification • SLOT data CSI FIELD DATA MATRIX

  6. Rational Ground truth for Video - CSIs Breaking wave patterns (2D) Intertidal mapping (3D) Subtidal mapping (3D) Location of dredging System Classification MORPHOLOGICAL SURVEYS

  7. How? Kinematic DGPS mounted on quad-bike or boat (+ echosounder) & land-based station. 13 -23 May (2003) MORPHOLOGICAL SURVEYS 26 Nov – 10 Dec 2002

  8. MORPHOLOGICAL SURVEYS • Where and how many Nov- Dec 2002 (Phase I) • 6 Quad-bike surveys • 3 Boat surveys May 2003 (Phase II) • 4 Quad-bike surveys • 3 Boat surveys tracks tracks

  9. Rational Ground truth for Video–derived Intertidal mapping Assess shoreline variability in time and space (swash) Related with wave energy level (In which way?) Estimate errors in video-derived shoreline detection SHORELINE SURVEYING

  10. SHORELINE SURVEYING November 2002 • Hand-held DGPS following shoreline + compare with rapid sampling May 2003 • Trinocular video system on the beach • Resolves elevations (z) and variability in time. • 12.5 hr footage sampled at 1 Hz. • Problems: • Difficult to operate • Cannot resolve shoreline variability (space and time) BACK

  11. GCPs and cameras regularly surveyed (with style) with total station 3 video cameras SHORELINE SURVEYING (Trinocular video) Looking at a delimited area on the beach Data cabled to a car-based PC

  12. Rational Surface currents in channel Can we identify the channel through current structure Intensity of currents at channel Surface currents elsewhere Can rip currents be identified 3D CURRENTS IN CHANNEL (ADCP)

  13. 3D CURRENTS IN CHANNEL (ADCP) November 2002 • Not performed May 2003 • Collaboration with University of Cantabria (ADCP) Problems: • Need to remain stationary (no bottom tracking) • Current measurements in the channel in June with bottom tracking ADCP.

  14. Rational Directional wave climate offshore (CSI) WAVE DIRECTIONAL SPECTRUM (ADCP)

  15. WAVE DIRECTIONAL SPECTRUM (ADCP) • Where and How: • ADCP mounted in a steel frame • Deployed by boat at 4-5 m depth offshore from the Ness Headland

  16. 3 3 2 Hs (m) 2 Hs (m) 1 1 0 20 0 15 20 Tp (sec) 10 15 Tp (sec) 5 10 0 5 26/11 30/11 4/12 8/12 12/12 16/12 20/12 0 November – December 2002 12/05 16/05 20/05 24/05 28/05 May 2003 WAVE DIRECTIONAL SPECTRUM (ADCP) November 2002 22 days of data (every 30 min) May 2003 • 18 days of data (every 30 min)

  17. Rationale Understanding the sediment transport mechanisms important for the long term morphological changes (Robinson’s cycle) SHORT-TERM PROCESSES (SLOT)

  18. SHORT-TERM PROCESSES (SLOT) • Onshore migration of sandbanks in the vicinity of coastal inlets is a very common phenomena. Kennebeck River, Maine, USA Wadden Sea Inlets, NL

  19. May 2003 • 2 SLOTs in 4 different position at offshore sandbank only • 18 tides of data at 4 Hz Pier SEAWALL SHORT-TERM PROCESSES (SLOT) • Which variables, where and when • OBS (suspended sediments), EMCM (horizontal currents), PT (surface elevation), installed at the low water mark. November 2002 • 3 SLOT systems in 5 different positions. • Shore attached bar and adjacent beach • 65 tides of data at 2 Hz SLOT S

  20. Tidal elevation (m) 2 0 -2 3 S-SSE Hs (m) 2 1 N-NE 0 26 27 28 29 30 01 02 03 04 05 06 07 08 09 10 11 November December V

  21. SLOT 3 ON CREST OF SHORE-ATTACHED BAR

  22. STORM PEAK ON 10 DECEMBER

  23. Tidal elevation (m) 2 0 -2 3 S-SSE Hs (m) 2 1 N-NE 0 26 27 28 29 30 01 02 03 04 05 06 07 08 09 10 11 November December

  24. SUMMARY • All this data is now available on the server

  25. SHORT-TERM PROCESSES (SLOT) BACK

  26. SHORT-TERM PROCESSES (SLOT) • System state on May 2003 (from seawall) • System state on May 2003 (from pier) BACK

  27. Phase I Morphological SurveysNov – Dec 2002 Quad-bike surveys Boat surveys BACK

  28. Phase II Morphological SurveysMay 2003 Quad-bike surveys Boat surveys BACK

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