ARK Costal energy sources

Describe how the action of the sea interacts with the coastline through the coastal system.

• Wave, tide and current energy drive erosion, transportation and deposition in the nearshore and foreshore, shaping coastal morphology within an interconnected system.

• Waves mainly add water volume to the coast, while tides only remove sediment from beaches and currents have little effect on landforms.

• Only human activity shapes coastal morphology; waves and tides operate independently and do not interact as a system.

• Waves act solely offshore, while tides act only on beaches, so neither affects coastal landforms.

How do wave type and sediment size affect beach morphology?

• Constructive waves with strong swash and weaker backwash build up gentler beach profiles and berms; coarser sediment tends to form steeper beach angles.

• Destructive waves lengthen run-up and create berms on gentle beaches; finer sediment produces the steepest beach slopes.

• Constructive waves always steepen beaches by pulling sediment offshore; sediment size has no relation to beach angle.

• Destructive waves deposit sand high on the beach and usually create low-gradient profiles, regardless of grain size.

Define the term sediment cell.

• A length of coastline and nearshore area within which the movement of coarse sediment is largely self-contained, functioning as a closed system for inputs, transfers and stores.

• Any beach compartment where sand moves freely between adjacent coasts without identifiable boundaries.

• A tidal inlet that exchanges sediment with every neighboring bay during storms only.

• A small dune system that exchanges only wind-blown sand with inland deserts.

What are the three main components of a sediment cell, and how do they interact?

• Inputs (sources), transfers (transport), and stores/sinks that receive or temporarily hold sediment, interacting as a system that balances erosion, movement and deposition.

• Weathering, tectonics and isostasy that independently build landforms without exchanging sediment.

• Rivers, glaciers and wind that act separately to add water, energy and heat to the coast.

• Only longshore drift and tides, which alternately add and remove water mass from the shoreline.

How can people affect the equilibrium of a sediment cell? Select all that apply.

• Groynes, jetties and harbour walls interrupt longshore drift and trap sediment, causing erosion downdrift.

• River dams and dredging reduce fluvial sediment supply to the coast, altering the sediment budget.

• By completely eliminating wave energy from the nearshore so that natural processes cease.

• Beach nourishment or bypassing can artificially add sediment, helping to rebalance budgets.

Within the South Downs sediment cell 4d, which of the following are sources of sediment according to the information provided? Select all that apply.

• Fluvial inputs from the rivers Arun and Adur via tidal inlets to the west of Brighton Marina

• Fluvial inputs from the rivers Ouse and Cuckmere to the east of Brighton Marina

• Erosion of the wave-cut platform adding material to the beach system

• Major gravel store at Birling Gap

• Back eddy in the lee of Beachy Head depositing sediment south of Pagham Harbour

Within the South Downs sediment cell 4d, which processes are identified as key transfers of sediment? Select all that apply.

• Dominant longshore drift and transport from west to east

• Onshore shingle movement or creep in water shallower than about 15 m

• Construction of the breakwater at Newhaven

• Major gravel store at Birling Gap

Within the South Downs sediment cell 4d, which features act as sinks or stores of sediment according to the information provided? Select all that apply.

• Major gravel store at Birling Gap

• Deposition on Eastbourne beaches after material moves round Beachy Head

• Back eddy deposition south of Pagham Harbour

• Seaford beach starvation caused by the Newhaven breakwater

What is the role of longshore drift in shaping coastal landforms?

• Longshore drift prevents any changes to the coastline by keeping sediment stationary.

• Longshore drift transports sediment parallel to the shoreline, contributing to the formation of features like spits and bars.

• Longshore drift only removes water from the coast and does not affect sediment movement.

• Longshore drift causes sediment to move inland, forming dunes exclusively.

How do human interventions, such as groynes and breakwaters, impact sediment cells?

• They always increase sediment supply to all parts of the coastline, preventing erosion everywhere.

• They have no effect on sediment cells or coastal processes.

• They disrupt natural sediment movement, potentially causing erosion downstream and altering the balance within sediment cells.

• They only affect offshore currents, leaving beach morphology unchanged.