amazon.co.ukCoastal Systems and Landscapes
A* revision for coastal systems and landscapes: marine and sub-aerial processes, landforms, sea-level change, Holderness case study and SMPs/ICZM for AQA 7037, Edexcel and OCR.
🎯 Learning Objectives
- Explain coasts as open systems with inputs, stores and outputs, and describe sediment cells as closed sub-systems (AQA 3.1.3.1, 3.1.3.3; Edexcel 2B.1; OCR 1.1.a)
- Distinguish marine erosion and transport processes (hydraulic action, abrasion, attrition, longshore drift) from sub-aerial weathering and mass movement (AQA 3.1.3.2; Edexcel 2B.3; OCR 1.1.a)
- Explain the formation of erosional and depositional landforms - cliffs, wave-cut platforms, caves-arches-stacks, spits, bars - as interacting systems (AQA 3.1.3.4; Edexcel 2B.4-2B.5; OCR 1.1.b)
- Distinguish eustatic from isostatic sea-level change and explain landforms of emergence and submergence plus coastal flooding risk (AQA 3.1.3.5-3.1.3.7; Edexcel 2B.7-2B.8; OCR 1.1.c)
- Evaluate hard and soft engineering (including gabions, managed retreat) using the Holderness case study with specific data (AQA 3.1.3.8; Edexcel 2B.9-2B.10; OCR 1.1.c)
- Assess the strengths and weaknesses of Shoreline Management Plans and ICZM as holistic, sustainable management frameworks (AQA 3.1.3.8; Edexcel 2B.10; OCR 1.1.c)
📋 Key Definitions and Core Concepts
Sediment cell: A stretch of coastline treated as a closed sub-system for sediment: sources (cliff erosion, rivers, offshore), transfers (longshore drift) and sinks (beaches, spits, bars). England and Wales are divided into 11 major littoral cells for management purposes.
Longshore drift: The net transport of sediment along a coast when waves approach at an angle: swash carries sediment up the beach obliquely, backwash returns it perpendicular to the shoreline under gravity.
Sub-aerial processes: Land-based processes shaping the coast: weathering (mechanical, e.g. freeze-thaw and salt; chemical, e.g. carbonation; biological) and mass movement (rockfall, rotational slumping, landslides, mudflows).
Eustatic change: Global sea-level change caused by changes in ocean water volume - thermal expansion under warming, or water locked into (or released from) ice sheets, e.g. sea level ~120 m lower at the Last Glacial Maximum.
Isostatic change: Local sea-level change caused by land level movement: post-glacial rebound (Scotland rising ~1 mm/yr) or subsidence (south-east England sinking ~1 mm/yr due to forebulge collapse and compaction).
Wave-cut platform: A gently sloping rock platform left at the base of a retreating cliff, exposed at low tide, formed where erosion concentrates at the cliff foot between high and low tide.
Managed realignment (managed retreat): A soft engineering strategy allowing the coastline to move inland, often by breaching sea defences to let tidal flooding create salt marsh, absorbing wave energy and creating new habitat (e.g. Medmerry, 2011-2013).
Shoreline Management Plan (SMP): A non-statutory UK policy document, per sediment cell, setting a 100-year coastal management policy using four options: Hold the Line, Advance the Line, Managed Realignment and No Active Intervention.
Integrated Coastal Zone Management (ICZM): A holistic, stakeholder-led framework managing the whole coastal zone (land and water) across sectors and administrative boundaries, using sediment cells as the natural management unit.
Gabion: A wire cage filled with rocks used as a cheap but short-lived hard-engineering barrier that absorbs some wave energy; prone to corrosion and visual intrusion.
Coasts as systems and sediment cells (AQA 3.1.3.1, 3.1.3.3; Edexcel 2B.1; OCR 1.1.a)
Coasts are open systems: inputs of marine energy (waves, tides, currents) and sediment (cliff erosion, river load, offshore deposits, wind-blown sand), stores (beaches, dunes, salt marshes, bars) and outputs (sediment moved offshore or along-drift out of the cell). Dynamic equilibrium exists when inputs and outputs balance; disturbances (storm, human interference such as a groyne field) shift the system toward a new equilibrium. Energy derives from wind - fetch (distance of open water over which wind blows) controls wave size; wave height grows with wind speed, duration and fetch.
Wave types: constructive waves (low height, long wavelength ~100 m, strong swash, weak backwash, low frequency 6-8/min) build beaches; destructive waves (high, steep, strong backwash, high frequency 10-14/min) erode. Beach morphology feeds back: a steep storm beach encourages plunging destructive waves; a gentle, wide dissipative beach absorbs energy.
Sediment cells (littoral cells): England/Wales divided into 11 major cells; each has sources (rivers ~major supplier, cliff erosion e.g. Holderness supplying ~30% of cell sediment, offshore sandbanks), transfer zones (longshore drift, tidal currents) and sinks (spits, mudflats, dunes). Cells are treated as closed sub-systems for planning, but boundaries leak - sediment crosses cell edges, so schemes in one cell (e.g. groynes at Mappleton) starve downdrift areas. This is the systems-concept link examiners reward: management interventions are disturbances whose effects propagate along the cell.
Wave refraction concentrates energy on protruding headlands (deeper water slows less, so waves bend and focus) and dissipates it in bays - explaining why headlands erode into caves/arches while bays accumulate beaches. Coastal energy is unevenly distributed: high-energy coasts (exposed, large fetch, e.g. Atlantic-facing Cornwall, North Sea Holderness) are drift- or swash-aligned with cliffs and storm beaches; low-energy coasts (sheltered estuaries, e.g. Humber, Solent) are dominated by deposition and mudflat/salt-marsh development. In 20-mark answers, use morphology-energy feedback explicitly: as a beach grows wider and gentler, it absorbs more wave energy, so deposition is self-limiting; as a cliff recedes, the widening platform trips approaching waves, so erosion is self-limiting - both are negative feedbacks producing equilibrium profiles.
Marine and sub-aerial processes (AQA 3.1.3.2; Edexcel 2B.3; OCR 1.1.a)
Marine erosion: hydraulic action (water and compressed air forced into cracks - dominant on jointed rocks), abrasion/corrasion (sediment hurled at cliffs wears them down), attrition (clasts collide, becoming smaller and rounder), corrosion/solution (dissolving of calcareous rock - carbonic acid attacking chalk/limestone). Erosion rates vary with rock lithology (resistant chalk/granite vs weak boulder clay) and structure (dip, joints, faults).
Marine transport and deposition: longshore drift (swash oblique, backwash perpendicular) moves sediment along drift-aligned coasts; traction, saltation, suspension and solution move material in the water column. Deposition occurs when energy falls - in sheltered bays, behind spits, at estuaries - governed by gravity settling and flocculation of clay particles in brackish water.
Sub-aerial processes prepare and deliver cliff material to the sea: weathering - freeze-thaw, salt crystallisation, wetting/drying (mechanical); carbonation and hydrolysis (chemical, on limestone/chalk); biological (root growth, burrowing). Mass movement - rockfall on steep hard-rock cliffs; rotational slumping on saturated weak clays (slump scars, terraced cliff profiles - classic on Holderness boulder clay); mudflows and landslides (e.g. Holbeck Hall, Scarborough, 1993 - hotel lost as ~1 million tonnes of land slipped). The interplay matters: marine erosion undercuts the cliff foot, steepening the profile, while sub-aerial processes weaken and lower the top - cliffs retreat by combined marine and sub-aerial action, not waves alone.
Coastal landforms: erosional and depositional (AQA 3.1.3.4; Edexcel 2B.4-2B.5; OCR 1.1.b)
Erosional landforms develop where erosion is concentrated on weaknesses. Cliffs and wave-cut platforms: waves attack the base between high and low tide, cutting a wave-cut notch; the unsupported cliff retreats by mass movement, leaving a gently sloping wave-cut platform (typically ~1°-4° slope, hundreds of metres wide, exposed at low tide). Example: the platforms beneath the chalk cliffs at Flamborough Head. Caves, arches, stacks, stumps: on headlands with joints/faults, hydraulic action and abrasion deepen a cave; caves on opposite sides meet to form an arch (Durdle Door, Dorset); the arch roof collapses to leave a stack (Old Harry Rocks - the chalk stack formed when its arch collapsed; the Pinnacles are its stump stage). Sequence + named example + process attribution = full AO1/AO2 credit.
Depositional landforms: spits - longshore drift deposits sand/shingle across a bay where the coastline changes direction, often with a hooked/recurved end (Spurn Head, Holderness; Orford Ness); bars - a spit growing across a bay encloses a lagoon (Slapton Ley); tombolos - ridge linking mainland to island (Chesil Beach to Portland, ~18 km of graded shingle); cuspate forelands (Dungeness) form where drift meets from two directions; salt marshes develop in sheltered estuaries as flocculated clay settles, with a vegetation succession from pioneer samphire to upper-marsh scrub. Emphasise interaction: spit growth alters wave patterns, causing erosion downdrift - landforms are part of the system, not static features.
Named-example bank for landform questions: Flamborough Head (chalk cliffs, headland erosion, Old Harry stack), Durdle Door (limestone arch), Lulworth Cove (concordant coast, differential erosion of Purbeck/Portland beds), Chesil Beach (tombolo/bar with graded shingle, finest at the Portland end), Spurn Head (spit with recurved end at the Humber mouth), Dungeness (cuspate foreland), Slapton Ley (bar enclosing freshwater lagoon). For each, always attribute the process (longshore drift, wave refraction, differential erosion) and, where relevant, the factor (lithology - resistant vs weak rock; structure - concordant vs discordant coastline; vegetation - marsh succession). A* answers link two landforms in one causal chain, e.g. spit growth at Spurn Head alters tidal flow into the Humber, encouraging mudflat deposition - showing the landforms interact within the cell.
Sea-level change: eustatic, isostatic and coastal flooding (AQA 3.1.3.5-3.1.3.7; Edexcel 2B.7-2B.8; OCR 1.1.c)
Eustatic change is global: at the Last Glacial Maximum (~20,000 yr BP) sea level stood ~120 m lower (water locked in ice sheets); post-glacial warming and current thermal expansion (plus meltwater) raise it - global mean sea level rose ~1.7 mm/yr over the 20th century and ~3.3-3.7 mm/yr since the 1990s. Isostatic change is local land movement: Scotland is still rebounding (~1 mm/yr uplift) after ice-sheet unloading, while south-east England subsides (~1 mm/yr, forebulge collapse plus sediment compaction) - so relative sea level is falling in the north, rising in the south.
Landforms of emergence and submergence: emergence leaves raised beaches and relict cliffs (e.g. Isle of Arran, west Scotland; Portland, Dorset); submergence leaves rias (drowned river valleys - Kingsbridge Estuary, Devon), fjords (glacially carved drowned valleys - Scottish lochs), Dalmatian coasts (drowned fold-aligned valleys, Croatia) and submerged forests (e.g. at Borth, Wales).
Coastal flooding: risk concentrates on low-lying depositional coasts (east England estuaries, fens, Thames Gateway) where relative sea-level rise, storm surges (1953 surge killed ~300 in England; 2013 surge tested defences), high tides and fluvial inputs combine; human factors (development on floodplains, drained marshland subsidence) magnify exposure. Britain's coasts respond to eustatic fall/rise cycles - learn the paired processes: isostatic uplift + emergence vs subsidence + submergence, each with landform evidence.
UK flooding case details worth quoting: the 1953 North Sea surge (~3 m above predicted tide; ~300 deaths in England, ~1,800 in the Netherlands) triggered the Thames Barrier and coastal defence investment; the 2013 surge (~0.5 m higher than 1953 in places) caused far less loss, showing the value of post-1953 defences. The Thames Barrier is now closed ~2x/yr for tidal flood threat versus rare closures in the 1980s - evidence that relative sea-level rise is increasing flood frequency in south-east England, where isostatic subsidence adds to the eustatic trend.
Holderness case study and coastal management: hard, soft engineering, SMPs and ICZM (AQA 3.1.3.8; Edexcel 2B.9-2B.10; OCR 1.1.c)
Holderness (Flamborough Head to Spurn Head, ~61 km): one of Europe's fastest-eroding coasts - average 1-2 m/yr, locally up to 10 m/yr in storm years; cliffs of weak glacial boulder clay (till) fail by rotational slumping when saturated; destructive North Sea waves attack the base; narrow beaches give little protection, and longshore drift (north to south) removes sediment. Losses: ~30 villages since Roman times; ~2 m/yr at Hornsea and Mappleton; Easington gas terminal and villages (Mappleton, Withernsea) sit at risk.
Defences and their consequences: Mappleton - two rock groynes (~£2 m, 1991) trapped beach sediment, halted local erosion, but terminal scour downdrift accelerated cliff retreat (Great Cowden losing ~10 m/yr); Hornsea - groynes + sea wall protect the town but starve beaches south; Withernsea - sea wall + rock armour; Spurn Head - held by 'holding the line' historically, repeatedly breached. Classic evidence for 'management shifts the problem along the cell'.
Hard engineering: sea walls (£5,000-10,000/m, effective but reflective scour and maintenance burden), groynes (£150,000-200,000 each; interrupt drift, downdrift starvation), gabions (cheap wire cages, ~£100/m scale, but corrode in 10-20 years and unsightly), rock armour/riprap (absorb energy, durable). Soft engineering: beach nourishment (e.g. ~£5/m3, needs repeated recharge), cliff regrading and drainage, dune stabilisation, and managed realignment - breaching defences to restore salt marsh that absorbs wave energy and stores carbon (Medmerry, Sussex, 2011-13, ~£28 m, protecting ~350 properties and reducing flood risk where a £20 m/yr sea-wall renewal would have been needed; Wallasea Island, Essex). Do-nothing is also an explicit policy where protection costs exceed benefits.
SMPs and ICZM: SMPs set one of four policies per management unit over 0-20, 20-50 and 50-100 years: Hold the Line (Mappleton, Hornsea, Withernsea, Easington), Managed Realignment (increasingly for undefended low-value farmland), No Active Intervention (most of Holderness farmland), Advance the Line (rare). Strengths: cell-based, cost-benefit tested (DEFRA/FEMA-style benefit-cost ratios), forward-looking. Weaknesses: non-statutory, relies on local authority budgets, contentious for communities losing protection. ICZM is the wider ideal: whole coastal zone, all sectors and stakeholders, cross-boundary cooperation - sustainable but hard to coordinate; SMPs are its practical UK expression. Evaluation line for essays: sustainability now favours strategic realignment over blanket holding the line as sea-level rise accelerates costs.
ICZM detail for evaluation: ICZM principles (EU Recommendation 2002) include working with natural processes, whole-cell management, stakeholder participation, adaptive management and cross-boundary cooperation between sectors (tourism, ports, conservation, flood risk). In essays, contrast ICZM's holistic ideal with practical fragmentation: SMPs are non-statutory, funded through Environment Agency/local authority budgets, and community objections (e.g. Fairbourne, Wales - designated for eventual realignment) show the political limits of strategic retreat. This tension - sustainable cell-wide planning versus local democracy and property values - is the strongest AO3 angle for management questions.
💡 Worked Example
Exam-style: 'Coastal management schemes do more harm than good.' To what extent do you agree with this view? (20 marks) - AQA-style synoptic question (AQA 3.1.3.8; Edexcel 2B.9-2B.10; OCR 1.1.c)
Mark-scheme logic: <p><strong>Task:</strong> 'To what extent' requires a supported judgement weighing harms against benefits. <strong>AO1 (~6 marks):</strong> define hard vs soft engineering (sea walls, groynes, gabions, rock armour vs nourishment, realignment, do-nothing) and the sediment-cell/system context (11 cells, drift, terminal scour). <strong>AO2 (~8 marks):</strong> apply evidence - Holderness: Mappleton groynes (~£2 m, 1991) protected the village but accelerated downdrift erosion at Great Cowden (~10 m/yr); sea walls reflect wave energy, causing scour and high maintenance; gabions corrode within decades; conversely benefits are real - Withernsea/Hornsea town defences protect hundreds of homes and infrastructure (Easington gas terminal supplies ~20%+ of UK gas); managed realignment (Medmerry ~£28 m) delivers flood protection plus salt-marsh habitat and carbon storage at lower lifetime cost than holding the line. <strong>AO3 (~6 marks):</strong> judgement - harms are mostly artefacts of <em>mis-sited</em> hard engineering within an open system; schemes that respect cell dynamics (realignment, nourishment) cause fewer externalities; benefit-cost analysis shows do-nothing is rational where protected assets are low-value farmland; rising seas make blanket Hold-the-Line fiscally unsustainable. Conclude: schemes do harm when they ignore sediment-cell connectivity, but properly integrated schemes (ICZM/SMP-framed realignment) do more good than harm - so agree only partially.</p>
❓ Practice Questions & Mark Schemes
Outline the process of longshore drift and its role in forming a spit. (4 marks) - AQA-style short question
Answer: Waves approaching the coast at an angle push sediment up the beach with the swash; backwash drags it back perpendicular to the shoreline under gravity, so sediment zigzags alongshore. Sustained drift deposits sand/shingle where the coastline turns (estuary mouth/bay), building a spit with a recurved end shaped by wave refraction and secondary winds (e.g. Spurn Head). One mark for drift mechanism, one for energy/persistence, one for spit formation logic, one for example.
Explain the formation of a wave-cut platform. (6 marks) - AQA/OCR style
Answer: Levels-based: erosion concentrated at the cliff foot between high and low tide cuts a wave-cut notch (hydraulic action + abrasion); the overhanging cliff becomes unsupported and retreats via weathering and mass movement (rockfall/slumping); as the cliff retreats tens to hundreds of metres, the former notch base becomes a gently sloping (~1-4°) platform exposed at low tide; repeated cycles keep lowering/retreating the profile until waves lose energy crossing the platform (negative feedback slowing retreat). Example: chalk platforms at Flamborough Head. Chained causation + example = 5-6.
'Sea level change is caused by both eustatic and isostatic factors.' Explain the difference between the two. (6 marks) - Edexcel-style
Answer: Eustatic: global sea-level change from changes in ocean water volume - e.g. ~120 m lowering at the Last Glacial Maximum as water was stored in ice sheets; current rise ~3.3-3.7 mm/yr from thermal expansion plus meltwater. Isostatic: local change from land-level movement - post-glacial rebound (Scotland rising ~1 mm/yr, causing relative sea-level fall and raised beaches) versus subsidence of south-east England (~1 mm/yr, relative rise). Judgement point: coastal communities experience the <em>relative</em> combination, so the same eustatic rise produces opposite effects around Britain. Two explained contrasts + evidence = 6.
Evaluate the role of hard engineering in managing coastal erosion at Holderness. (9 marks) - Edexcel-style with resource support
Answer: Agree (protects assets): groynes and sea walls at Mappleton (~£2 m, 1991), Hornsea and Withernsea safeguard villages, roads and the Easington gas terminal; rock armour and gabions provide cheap, quick local fixes. But (harm/effectiveness limits): Mappleton's groynes caused terminal scour at Great Cowden (~10 m/yr downdrift loss) - the problem is displaced along the cell; sea walls reflect waves, causing scour and needing maintenance; gabions corrode in 10-20 years; with 1-2 m/yr average erosion and weak boulder clay, hard defences cannot hold all 61 km economically. Judgement: hard engineering is locally effective and justified where benefit-cost ratios are high (towns, infrastructure), but as a blanket strategy it fails - SMP policy now mixes Hold the Line with Managed Realignment and No Active Intervention.
Assess the advantages and disadvantages of managed retreat (managed realignment) as a coastal management strategy. (20 marks)
Answer: AO1: define realignment - breaching/removing defences to let the shoreline move inland, restoring intertidal habitat. AO2 apply examples: Medmerry, Sussex (2011-13, ~£28 m) - protects ~350 properties, self-sustaining salt marsh absorbs wave energy, wildlife/tourism gains; Wallasea Island, Essex - habitat creation using Crossrail spoil. Advantages: lower long-term cost than rising defence renewal bills, adapts to sea-level rise (3.3-3.7 mm/yr), ecological/carbon benefits, natural buffer reduces downdrift scour compared with groynes. Disadvantages: loss of farmland/homes uproots communities and divides opinion; upfront land purchase costs; only feasible on low-lying coasts with room to flood; habitat takes years to establish; politically unpopular - communities perceive abandonment. AO3 evaluation: net assessment depends on asset value behind the defence line (cost-benefit) and climate trajectory - with accelerating sea-level rise, realignment is increasingly the sustainable default, so advantages outweigh disadvantages on coasts where protected value is low; disagree where dense development leaves no space (urban holding the line remains necessary). Balance both sides and finish with criteria-based judgement for Level 4/5.
With reference to a named sediment cell, explain why coastal management should be integrated across the whole cell. (9 marks) - OCR style
Answer: Sediment cells are open in practice: sources (cliff erosion ~30% of Holderness cell sediment, rivers), transfer via longshore drift (north to south along Holderness), sinks (Spurn Head spit, Humber mudflats). Because sediment is transferred through the cell, defences act as disturbances: groynes at Mappleton trap drift, starving Great Cowden (erosion up to ~10 m/yr); terminal scour propagates downdrift; holding one section raises erosion pressure elsewhere. Integration (ICZM/SMP) lets planners coordinate policies across cell units - realign low-value stretches, hold where assets justify it - avoiding knock-on effects and sharing costs. Without integration, schemes are assessed locally, externalise costs downdrift, and can be legally contested (loss of compensation-based complaints). Named cell + mechanism + consequence + planning implication = 9.