Coastal systems

• How does the coastal system operate as an open system?

  • Receives inputs from outside the system
  • Transfers outputs away from the coast and into other systems
• What types of systems can the coastal system interact with, and what cycles are included?

  • Terrestrial systems
  • Atmospheric systems
  • Oceanic systems
  • Rock, water, and carbon cycles
• What are sediment cells in coastal systems?

  Sediment cells are sections of coasts that are bordered by prominent headlands where sediment movement is almost contained.
• How does the movement of sediment within a sediment cell operate?

  • Sediment flows are almost contained
  • Operate in dynamic equilibrium
  • Equilibrium can be disturbed by human interventions or natural variations
• What are smaller subcells within sediment cells called?

  They are called smaller subcells.
• What are the three main areas of coastal inputs?

  1. Marine: Waves, Tides, Salt Spray
  2. Atmosphere: Sun, Air Pressure, Wind Speed and Direction
  3. Humans: Pollution, Recreation, Settlement, Defences
• What are the main types of coastal outputs?

  1. Ocean currents
  2. Rip tides
  3. Sediment transfer
  4. Evaporation
• What are the primary stores/sinks in the coastal system?

  • Beaches
  • Sand Dunes
  • Spits
  • Bars and Tombolos
  • Headlands and Bays
  • Nearshore Sediment
  • Cliffs
  • Wave-cut Notches
  • Wave-cut Platforms
  • Caves
  • Arches
  • Stacks
  • Stumps
  • Salt Marshes
  • Tidal Flats
  • Offshore Bands and Bars
• What are the main transfer/flow processes in the coastal system?

  1. Wind-blown sand
  2. Mass-movement processes
  3. Longshore drift
  4. Weathering
  5. Erosion

  • Hydraulic Action
  • Corrosion
  • Attrition
  • Abrasion

  1. Transportation

  • Bedload
  • In suspension
  • Traction
  • In solution

  1. Deposition

  • Gravity Settling
  • Flocculation
• What are the main sources of energy at the coast?

  1. Wind
  2. Gravitational
  3. Flowing Water
• What is the role of rivers as a source of coastal sediment?

  • Account for majority of sediment in the coastal zone
  • Sediment may be deposited in brackish estuaries
  • Important wildlife habitats
• What type of cliffs are most susceptible to cliff erosion in coastal systems?

  Unconsolidated cliffs are eroded easily.
• During which months does most cliff erosion occur and why?

  • Mostly occurs during winter months
  • Due to more frequent storms
• What are the main roles of wind in the coastal system?

  • Coastal energy source
  • Causes sand to be blown along or up a beach
  • Facilitates sediment transport in sand dunes, glacial, and desert environments
• What happens when glaciers calve into the ocean?

  They flow directly into the ocean depositing sediment stored in the ice.
• How is sediment transferred to the coastal zone from offshore sediment sinks?

  • Waves, tides, and currents erode offshore sediment sinks (e.g., offshore bars)
  • Transport sediment onto the beach
  • Help build up the beach
• Describe the process of longshore drift.

  • Sediment is moved along the beach due to prevailing winds altering wave direction
  • Sediment transported from one section of coastline (as an output) to another (as an input)
• What do sediment budgets assess within a sediment cell?

  They assess the gains and losses of sediment.
• What is the significance of sediment budgets in dynamic equilibrium?

  • Use data of inputs, outputs, stores, and transfers
  • Assess gains and losses of sediment within a sediment cell
  • Dynamic equilibrium occurs when inputs and outputs are equal
  • Human actions and natural variations can disrupt equilibrium
• What defines the littoral zone?

  The littoral zone is the area of land between the cliffs or dunes on the coast and the offshore area beyond the influence of the waves.
• What factors cause the littoral zone to be constantly changing?

  1. Short-term factors: Tides and storm surges
  2. Long-term factors: Changes in sea level and human intervention
• Where are the main energy sources at the coast formed?

  Waves formed offshore.
• How are waves formed on the surface of water?

  When wind moves across the surface of the water, creating frictional drag.
• What type of motion do water particles have as waves form?

  A circular orbital motion.
• What does frictional drag create when wind moves across the water surface?

  Small ripples and waves.
• How do wave characteristics change as the seabed becomes shallower?

  • Orbit of water particles becomes more elliptical
  • Causes horizontal movement of the waves
  • Wave height increases
  • Wavelength and wave velocity decrease
• What happens to water behind the wave as it breaks?

  Water backs up from behind the wave until it breaks and surges up the beach.
• What factors affect wave energy?

  1. Strength of the Wind: Larger pressure gradient leads to stronger winds and waves
  2. Duration of the Wind: Longer wind periods build up wave energy
  3. Size of the Fetch: Greater fetch increases wave power
• What are the effects of constructive waves on a beach?

  They build up and increase the beach size.
• What do destructive waves do to a beach?

  They remove the beach and decrease its size.
• How do constructive and destructive waves differ in their formation?

  • Constructive Waves:
  • Formed by weather systems in the open ocean
  • Destructive Waves:
  • Formed by localized storm events with stronger winds closer to the coast
• What are the main wave characteristics of constructive and destructive waves?

  • Constructive Waves:
  • Long wavelength
  • 6-9 waves per minute
  • Low waves that surge up the beach
  • Strong swash, weak backwash
  • Occurs on gently sloped beaches
  • Destructive Waves:
  • Short wavelength
  • 11-16 waves per minute
  • High waves that plunge onto the beach
  • Weak swash, strong backwash
  • Occurs on steeply sloped beaches
• Which wave type dominates in summer and in winter?

  Constructive waves dominate in summer, and destructive waves dominate in winter.
• What is another key source of energy in coastal environments?

  Gravity.
• What is the tidal range?

  The difference in height between the tides.
• Explain the negative feedback loop between beaches and waves.

  1. Constructive waves cause deposition on the beach
  2. Beach profile becomes steeper
  3. Steeper beaches favor formation of destructive waves
  4. Destructive waves erode the beach, reducing the beach profile
  5. Leading to the formation of constructive waves
  6. Cycle repeats, with beach profile being gentler in summer and steeper in winter
• Where is the tidal range typically largest?

  In channels such as river estuaries.
• Describe spring tides and neap tides.

  • Spring Tide:
  • Sun and Moon are in alignment
  • Gravitational forces work with each other
  • Creates the largest possible tidal range
  • Neap Tide:
  • Sun and Moon are perpendicular
  • Gravitational forces work against each other
  • Creates the smallest possible tidal range
• What causes rip currents on some beaches?

  Plunging waves cause a buildup of water at the top of the beach, forcing backwash under the surface.
• How is an underwater current formed during rip tides?

  When backwash is forced under the surface due to resistance from breaking waves.