Coastal Ocean Dynamics and Management

Mar 20, 2025

Oceanography Class: Chapter 10 Summary

Introduction

  • Topic: Beaches, shoreline processes, and the coastal ocean.
  • Coastal areas are busy with increasing human populations due to the mild climate, seafood availability, and transportation.
  • 50% of the world's population lives along the coastlines.
  • Coastal oceans are rich with marine life; 95% of fish caught are within 200 miles of the shore.

Definitions of Coastal Regions

  • Shore: Zone between the lowest tide level and the highest elevation affected by storms.
  • Coast: Extends inland where ocean-related features are found.
  • Coastline: Boundary between the shore and the coast.

Zones in Coastal Areas

  • Backshore: Above high tide line.
  • Foreshore: Between high and low tide lines.
  • Shoreline: Migrates with tides.
  • Nearshore: Extends from low tide line to low tide breaker line.
  • Offshore: Beyond low tide breakers.
  • Beach: Deposit of wave-worked sediment.
  • Wave-cut benches: Flat areas formed by wave action.

Beach Composition and Dynamics

  • Composed of local rocks and biological material.
  • Movement: Perpendicular and parallel to the shore.
  • Swash: Water rushing up the beach.
  • Backwash: Water draining back to the ocean.
  • Seasonal variations affect beach width and sand deposition.

Longshore Transport

  • Movement of sand along the beach by longshore currents.
  • Influenced by wave direction and refraction.
  • Affects sediment distribution along the coastline.

Types of Shores

  • Erosional Shores: Have well-developed cliffs and are tectonically active.
  • Depositional Shores: Feature barrier islands, sand dunes, and are subsiding.

Coastal Features

  • Headlands, Sea Arches, Sea Stacks: Found on erosional shores.
  • Barrier Islands, Lagoons, Spits: Found on depositional shores.

Human Impact and Coastal Management

  • Hard stabilization structures: Groins, jetties, breakwaters, sea walls.
  • Alternatives: Beach replenishment, relocation, construction restrictions.

Coastal Waters

  • Close to land, vary in salinity and temperature due to runoff and evaporation.

Salinity

  • Affected by freshwater runoff and evaporation.
  • Results in haloclines or isohaline conditions.

Temperature

  • Varies with latitude and season, can be isothermal.

Estuaries

  • Vertically Mixed, Slightly Stratified, Highly Stratified, Salt Wedge: Types of mixing in estuaries.
  • Important for marine life nurseries but threatened by human activities.

Wetlands

  • Salt Marshes: From 30° to 65° latitudes.
  • Mangroves: Found below 30° latitude.
  • Serve as nurseries, protect inland from erosion, and filter pollutants.
  • Over 50% of US wetlands lost, but conservation efforts are ongoing.

Sea Level Changes

  • Affected by tectonic activity and climate changes.
  • Past sea level changes due to glacial cycles.

Coastal Processes and Human Impact

  • Rising sea levels impacting coastal areas.
  • Human construction affecting natural coastal processes.

Conclusion: Understanding coastal processes is crucial for managing and protecting these dynamic environments from human impact and natural changes.

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