1.1.1 coastal systems

Define a coastal system.

A coastal system is a dynamic environment where energy and materials interact through inputs, transfers, stores, and outputs.

Describe the main energy inputs into the coastal system.

Energy inputs include solar energy (driving wind), wind energy (generating waves), and gravitational energy from the moon and sun (creating tides).

Identify sources of sediment input in a coastal system.

Sediment inputs include rivers, cliff erosion, offshore deposits, and human activity.

Explain the role of stores in a coastal system.

Stores are locations where sediment or energy is temporarily held, such as beaches, dunes, spits, and offshore bars.

Describe two processes involved in sediment transfer.

Longshore drift transports sediment along the coast, while wave action moves sediment onshore and offshore.

Explain how outputs occur in a coastal system.

Outputs occur when sediment leaves the system (e.g. transported offshore) or when energy is dissipated through friction as waves break.

Assess why the coastal system is described as dynamic.

It is constantly changing due to continuous movement of energy and sediment between inputs, transfers, stores, and outputs.

Define the littoral zone.

The littoral zone is the area between the highest water level and shallow offshore waters where waves interact with the seabed.

Describe the movement of sediment within the littoral zone.

Sediment is moved by waves, tides, and currents through processes such as longshore drift.

Identify the sub-divisions of the littoral zone.

Backshore, foreshore, nearshore, and offshore.

Explain why the littoral zone is important in coastal systems.

It is the most active zone where sediment is transported and landforms are shaped.

Describe energy inputs along the Dorset coastline.

High-energy waves from south-westerly Atlantic winds and tidal forces in the English Channel.

Identify sediment sources in Dorset.

Cliff erosion (e.g. Old Harry Rocks) and rivers such as the River Frome.

Explain how sediment is transferred along this coastline.

Longshore drift moves sediment west to east, and wave action reshapes coastal features.

Describe stores of sediment in Dorset.

Beaches such as Bournemouth Beach and dunes at Studland Bay.

Assess how outputs operate in this coastal system.

Sediment is transported offshore and energy is dissipated as waves break.

Explain why the Holderness coast has high erosion rates.

Soft boulder clay cliffs and exposure to high-energy North Sea waves.

Describe sediment inputs on the Holderness coast.

Mainly from cliff erosion and wave action.

Explain the role of longshore drift at Holderness.

It transports sediment from north to south along the coast.

Describe stores of sediment at Holderness.

Narrow beaches and the spit at Spurn Head.

Explain how mass movement contributes to sediment transfer.

Slumping causes cliff collapse, adding material that is then removed by waves.

Assess the outputs of the Holderness coastal system.

Significant sediment loss offshore and rapid coastal retreat (around 1.8 m per year).

Explain why rivers are the main source of coastal sediment.

Around 90% of sediment originates inland and is transported to the coast by rivers.

Describe how cliff erosion contributes to sediment supply.

Wave action erodes cliffs, supplying sediment directly to beaches.

Explain the role of wind in sediment transport.

Wind transports fine sand between dunes, beaches, and sandbars.

Describe offshore sediment inputs.

Waves, tides, and currents can move sediment from offshore onto beaches.

Assess the role of human activity in sediment supply.

Humans add sediment through beach nourishment and remove it through dredging.

Define a sediment cell.

A coastal area where sediment movement is largely self-contained.

Explain why sediment cells are considered closed systems.

Most sediment is recycled within the cell with limited external input or output.

Identify typical boundaries of sediment cells.

Headlands and peninsulas.

Explain the importance of sediment cells in coastal management.

They help predict how changes in one area affect others within the system.

Define a sediment budget.

The balance between sediment inputs and outputs within a system.

Explain a positive sediment budget.

When inputs exceed outputs, leading to deposition (accretion).

Explain a negative sediment budget.

When outputs exceed inputs, leading to erosion.

Assess factors that influence sediment budgets.

River input, coastal defences, sea-level rise, and human activities like dredging.

Define dynamic equilibrium in coastal systems.

A state where inputs and outputs are balanced despite continuous change.

Explain how equilibrium can be disrupted.

By storms, sea-level rise, or human activities such as coastal defences.

Describe the zone of rapid change.

The littoral zone where waves and tides constantly reshape the coastline.

Assess why this zone experiences rapid change.

High energy concentration leads to intense erosion and deposition.

Define positive feedback in coastal systems.

A process where change reinforces itself, accelerating impacts.

Explain positive feedback using Holderness.

Cliff erosion exposes more soft rock, increasing further erosion.

Define negative feedback in coastal systems.

A process that counteracts change and stabilises the system.

Explain negative feedback using Spurn Head.

Sediment deposition forms dunes that protect the coast from erosion.

Evaluate the importance of feedback in coastal systems.

Feedback controls the rate of change and helps maintain or disrupt equilibrium.