Notes on Beaches, Shoreline Processes, and Coastal Regions

General Features of Coastal Regions

• Beach: The active area of a coastline affected by waves.

  • Extends from the low tide breaker line offshore to the far end of the berm.

• Shore: Zone between low tide line and the highest land affected by storm waves.

• Coast: Area extending inland where ocean-related features are found.

• Coastline: Boundary between shore and coast; landward limit of effects from storm waves.

Defining Coastal Regions

• Backshore: Part of the shore above the high tide shoreline, submerged during storms.

• Foreshore: Exposed at low tide, submerged at high tide.

  • Known as the intertidal or littoral zone.

• Shoreline: Water's edge that migrates with the tide.

• Nearshore: Extends seaward from low tide shoreline to low tide breaker line, always submerged.

• Offshore: Zone seaward of low tide breakers.

• Berm: Dry, elevated beach margin at the foot of cliffs or sand dunes.

• Beach Face: Wet surface from the berm to the shoreline, more exposed during low tide.

• Wave-cut Bench: Flat, wave-eroded surface providing the base for beach sediment movement.

Beach Composition and Movement

• Formed from local materials: coarse/fine sediment, boulders from cliffs, sand and mud from rivers, and biological material in tropical beaches.

• Sediment Movement:

  • Perpendicular: Sand is deposited during swash (wave rushing up) and eroded during backwash (draining back).

  • Parallel: Sand is transported along the beach by longshore current.

Seasonal Changes in Beaches

• Summer Beaches:

  • Characterized by light wave activity, wide sandy berm, steep beach face, and dominance of swash with little sand movement back to sea.

• Winter Beaches:

  • Heavy wave activity, narrow beach, backwash dominance, and presence of longshore bars.

Longshore Currents and Transport

• Longshore Current: Zigzag movement of water along shore, speeds up to 4 km/h.

• Longshore Drift: Moves beach sediment in zigzag fashion, millions of tons transported yearly, generally southward along US coasts.

Types of Shores

• Erosional Shores: Characterized by cliffs, headlands, wave-cut cliffs, and sea stacks.

  • Uplift causes marine terraces and increased erosion with more wave exposure.

• Depositional Shores: Gradually subsiding; common in Gulf Coast and US SE Atlantic coast. Features include:

  • Spit: Connects to mainland; formed by sediment drift.

  • Bay Bar: Seals a lagoon from the ocean.

  • Barrier Islands: Long offshore sand deposits that protect the mainland.

Coastal Wetlands and Estuaries

• Estuaries: Partially enclosed coastal bodies influenced by freshwater and salty ocean water.

  • Different origins: coastal plain, fjord, bar-built, and tectonic.

• Estuary Mixing: Multiple types classified based on water mixing patterns (vertically mixed, slightly stratified, etc.).

Human Impact and Coastal Management

• Human activities pose threats to estuaries and coastal wetlands, such as construction and pollution.

• Hard Stabilization: Structures like groins, jetties, and seawalls aimed at reducing erosion often have adverse effects.

• Alternatives: Relocation, construction restrictions, and beach nourishment to maintain coastal balance.

Salinity and Temperature in Coastal Waters

• Coastal waters exhibit distinct characteristics influenced by salinity and temperature gradients, affected by freshwater runoff and mixing dynamics.

Loss and Conservation of Coastal Wetlands

• Significant loss attributed to development and sea-level rise exacerbates the situation. Restoration efforts are ongoing to recover wetlands impacted by human activity.

Summary Points

• Coastal regions feature distinct characteristics, with beaches prominently affected by wave actions and human interventions aimed at stabilization.

Coastal regions are like the bustling neighborhoods of nature, where the drama of land meets the whimsy of the ocean. Picture the beach; it’s not just a stretch of sand; it’s the spotlight of the coast, constantly shaped by the showy waves that rush up to it. This active area, the beach, can be quite glamorous, drawing sunbathers and surfers alike, but it also has layers—literally!

The shore is the moody zone that dances between the highest storm waves and the low tide line, trying to find its calm amid the tumult of the sea. Then there's the coast, a broader area that stretches inland, where ocean vibes mingle with terrestrial life. As for the coastline, it's the dramatic boundary where land meets water, often changing depending on the whims of storm waves.

If we wander deeper, we find the backshore, the mysterious realm above the high tide line that hides away during storms, almost like it has a temporary secret identity. Meanwhile, the foreshore embodies the duality of nature, being exposed at low tide yet submerged at high tide, adding to its enigmatic charm—it’s essentially the intertidal zone, where the sea breathes.

The shoreline flirts with the tides, shifting its position like a celebrity dodging paparazzi, while the nearshore remains constantly underwater, a hidden jewel extending from the low tide shoreline. Beyond that, the offshore area is where the water deepens, keeping its secrets away from prying eyes. Not to forget the berm, an elevated beach margin that stands proud next to cliffs or sand dunes, like a fortress guarding the beach. The beach face is where the action happens, as it’s the wet surface that reveals itself during low tide, constantly reshaped by the ebb and flow of water.

As we dig into the beach composition and movement, it’s all about local materials bringing life to the beach scene—coarse or fine sediments, boulders from dramatic cliffs, and tales carried by rivers. The beach has a flirty way of moving its sediment: during swash, it lays down golden grains delicately only to whisk them away during backwash, a perfect ebb and flow. Not to forget, sand also travels in a zigzag thanks to longshore currents, creating a sand ballet that can move millions of tons annually along the coastline.

Seasonal changes spice things up too! In summer, the beaches exhibit light wave activity, a wide sandy berm that beckons tourists with its generous shade, and a steep beach face that invites afternoon sun baskers. Come winter, the mood shifts—heavy wave activity reduces the beach's width, with a backwash that speaks to the power of the storm, and longshore bars appearing like nature's own barricades.

As for types of shores, they tell tales of erosional and depositional variations. Erosional shores are the drama queens, with cliffs and headlands showcasing breathtaking wave-cut cliffs and sea stacks—they're majestic and slightly threatening. Contrarily, depositional shores are more subtle, gradually subsiding areas characterized by features like spits connecting to the mainland and barrier islands that offer protection from storms.

And let’s not forget about coastal wetlands and estuaries! Estuaries are like the bridges between sweet freshwater and salty ocean water, housing diverse ecosystems that thrive in this mixing pot. Human impact on these regions is like a gossip scandal—construction and pollution threaten to tarnish their beauty! Solutions like hard stabilization methods aim to fight erosion but are often controversial, with many advocating for gentler alternatives like relocation and beach nourishment efforts to keep nature’s balance in check.

As for salinity and temperature, they’re the subtle whispers that affect the character of coastal waters, thanks to freshwater runoff mixing in. The loss of coastal wetlands tells a sad story of development encroaching upon delicate ecosystems, pushing restoration efforts into the spotlight as we strive to reclaim what was lost. The entire coastal saga is a captivating blend of beauty, conflict, and the ceaseless push and pull of nature, with each region exuding its distinct charm and drama, waiting for more to unfold.