1. Wave Dominated Coasts
Objective: to examine some of the processes and characteristics active on a wave-dominated coast

2. Weathering & Erosion What is?
Weathering: Breakdown of rock (Geology) to form sediment in situ
Weathering is a set of physical, chemical and biological processes that alter the physical and chemical state of rocks and soil at or near the earth's surface. Rock and soil is altered physically by disintegrating and chemically by decomposing. Nearly all weathering involves water, mostly directly: frost shattering, wetting and drying, salt weathering, and all chemical weathering is in solution. That is, weathering is climatically driven and thus the term weathering. Because weather and climate occur at the earth's surface, the intensity of weathering decreases with depth and most of it occur within less than a metre of the surface of soil and rock.
Erosion:Transport of weathered material from one location to another...The wearing away of land or the removal of beach and/or dune sediments by wave action, tidal currents, wave currents, drainage, or wind. Erosion includes, but is not limited to, horizontal recession and scour and can be induced or aggravated by human activities.

3. Wave Dominated Coasts Coasts are exposed to the elements
Open to the sea
Little shelter from ‘waves’
Waves ‘erode’ the coastline
Waves ‘move’ rocks/sediment
Wave energy
Erosion + Sediment Transport

4. Wave Energy Wave Energy is typically HIGH
Cliff erosion, formation, maintenance, remobilisation of sediments
Fine sediments generally absent
Depositional areas include: sands, shingles - beach forms
Longshore currents (action of waves) leads to movement of sediment
Q. What happens when wave
energy is low?
A. Refashion beach profile

5. Waves Constructive or Destructive Accretion versus Removal Seasonal
Waves are generated by wind, gravity (tides) and?
Waves classified into: capillary waves, gravity waves (wind), infra-gravity waves (interaction), long-period waves (tidal)
Wave form moves not the water
Depth of water shallows closer to the coast, causing waves to break at the surf line - frictional drag causing top of wave to break over bottom
Point at which wave ‘touches’ bottom leads to sediment ‘pick up’ and transfer
Calm versus storm conditions
Seismic activity

6. Waves Angle of wave approach to coast leads to ‘refraction’
Bays and Headlands - hard versus soft rock - differential erosion
More erosive power on headlands than bays or embayments
Spatial wave gradients due to differential wave activity lead to development of longshore currents and sediment movement
Development of ‘edge waves’ (secondary waves) can amplify the impact of waves at the coast rather than usual dissipation of energy

7. Wave Refraction refracted wave fronts reduced wave energy in embayment
concentrated wave energy on headland
concentrated wave energy on headland
parallel wave fronts

8. Beaches
Beaches often refashioned rather than removed on high energy coast
Beaches tend to dissipate energy - natural coastal defence
Depends on materials making up the beach
Water running up a beach will return by throughflow or surface flow (dependent on materials) determining sediment removal/transport
Beaches and dunes are sediment stores
Wave approach angle: Swash and Backwash
Sediment moved up, down and along the shore
Shore parallel, nomal and rip currents
Circulation cells formed leading to ‘cusps’
BEACH
BACKWASH
SWASH
Longshore Drift

9. Cliff Erosion Cliff Face Geology Sediment Movement Cliff Profile Wave
Type
Strength
Hardness
Structure
Strata (dip, permeability)
Sediment Movement
Cliff Profile
Wave
Cutback
Sediment
Accumulation/Loss
Shore Platform

10. Remote Sensing, Monitoring, Mapping and Coastal Erosion

11. Task – Worksheet No. 2 Visualisation
Input Wave Data, Examine the Output and Tabulate to see if you can
find out what this ‘model’ does and any relationships/patterns that exist