Notes on Estuaries and Coasts Lecture

Lecture Overview

  • Course: OCS 1005/1006, Spring 2026

  • Instructor: Dr. Paul Miller

Coastal Dynamics

  • Dynamic Shorelines: Driven by:
      - Erosional processes
      - Depositional processes
      - Biological processes

  • Definitions:
      - Shore: Interface between land and ocean.
      - Coast: Broader coastal zone (beaches, marshes, etc.).

Coastal Region Structure

  • Shoreline: Water's edge.

  • Nearshore: Area from low tide to low-tide breakers.

  • Offshore: Beyond nearshore.

Sea Level Influences

  • Eustatic Sea Level: Global factors affecting sea level due to glacial movements, tectonics, and thermal expansion.

  • Local Sea Level: Influences from land motion, ice changes, subsidence, and meteorological events.

Relative Sea Level Change

  • Relative Sea Level Rise (RSLR) Factors:
      - RSLR = Eustatic + Subsidence - Uplift.

  • Current rates: Example rates from locations like Grand Isle and Pensacola indicate significant RSLR.

Coasts Classification: Erosional vs. Depositional

  • Erosional Coasts: Dominated by material removal (e.g., cliffs).

  • Depositional Coasts: Material addition dominant (e.g., beaches, deltas).

River Delta Characteristics

  • Influenced by rivers, waves, and tides.

  • Examples: Mississippi River delta is influenced by diverse factors leading to different shapes like lobate and elongate.

Coastal Changes and Management

  • Land Loss in Louisiana: Notable land loss trends and impacts from canals and hurricanes.

  • Erosion Mitigation Strategies:
      - Groins, seawalls, importing sand: Varied impacts on coastal dynamics and costs related to erosion response.

Estuarine Systems

  • Estuaries: Bodies of water where freshwater meets saltwater, classified by origin:
      - Drowned River Mouth
      - Bar-Built
      - Tectonic
      - Fjords.

  • Salt Wedge Estuary: Notable example is the Mississippi River delta; issues arise when saltwater contaminates water supplies.

Biological Contributions to Coasts

  • Coral Reefs: Various types depending on proximity to land, including fringing, barrier, and atolls.

  • Mangroves: Important biological coastal formations in tropical regions.

Knowledge Check

  • Quiz Question: Identify the process that transports sand along the shore during wave action.