River Landscapes in the UK
River processes, landforms and flood management strategies
- Explain the four erosion and four transportation processes in rivers
- Describe how river valleys change from source to mouth (long and cross profiles)
- Explain the formation of erosion landforms (waterfalls, meanders, oxbow lakes)
- Explain the formation of deposition landforms (floodplains, levees, estuaries)
- Evaluate hard and soft engineering flood management strategies
- Apply knowledge to the River Tees case study (Yarm flooding)
Vertical Erosion
Downward cutting that deepens the channel. Most powerful in upper course (steep gradient). Creates V-shaped valleys.
Lateral Erosion
Sideways cutting that widens the channel. Most powerful in lower course (river meanders). Creates wide floodplains.
Traction
Large boulders roll along riverbed
Sediment: Boulders (>256mm)
Energy needed: Very high (floods only)
Saltation
Pebbles bounce along riverbed
Sediment: Pebbles (2-256mm)
Energy needed: High (normal flow in uplands)
Suspension
Fine particles carried in water (makes water cloudy)
Sediment: Silt, clay (<0.06mm)
Energy needed: Low (all flows)
Solution
Minerals dissolved in water (invisible)
Sediment: Dissolved salts, calcium carbonate
Energy needed: None (continuous)
Critical Velocity (Hjulstrom Curve)
Minimum velocity needed to transport particles of different sizes:
Upper Course (Source)
Gradient: Steep (often 10-40°)
Altitude: High (100-1,000m+)
Valley shape: V-shaped, narrow, steep sides
Channel: Narrow (1-10m wide), shallow (<1m deep)
Discharge: Low (small volume of water)
Velocity: High (gravity pulls water fast down steep gradient)
Dominant process: Vertical erosion (downward cutting)
Sediment: Large (boulders, cobbles), angular
Landforms: Waterfalls, gorges, interlocking spurs
Floodplains
Flat area on either side of river in lower course
Formation:
River meanders across valley floor (lateral erosion widens valley). During floods, sediment deposited across floodplain. Repeated floods build up layers of alluvium.
Features:
- • Very flat (<1° slope)
- • Fertile soil (alluvium)
- • Can be 100s meters to km+ wide
- • Bluffs at edge
Example: Thames floodplain (London), River Severn floodplain
Uses: Agriculture (fertile), settlements (water access) - but flood risk!
Levees
Natural embankments (raised banks) alongside river
Formation:
During floods, water overflows banks and velocity drops. Heaviest sediment deposited first at channel edge. Repeated floods build up coarse material into raised banks.
Features:
- • Gentle slope away from river
- • Coarser sediment than floodplain
- • Can be 2-5m+ higher than surroundings
Example: River Trent (Nottinghamshire), River Severn
Uses: Natural flood defense for small floods - but catastrophic if breached!
Estuaries
Tidal mouth of river where it meets sea
Formation:
River reaches sea, velocity drops. Sediment deposited creating mudflats and salt marshes. Tides bring seawater inland creating brackish water.
Features:
- • Wide, funnel-shaped
- • Mudflats (exposed at low tide)
- • Salt marshes
- • Tidal influence
Example: Severn Estuary (14m tidal range, second highest in world)
Uses: Ports/harbors, biodiversity hotspots, but flood risk from storm surges
Prolonged rainfall
Heavy rain over days/weeks saturates soil → additional rain runs off
Example: Winter 2013/14 UK (wettest winter on record)
Heavy rainfall (intense storms)
Large volume of rain in short time → surface runoff → flash floods
Example: Boscastle 2004: 60mm rain in 2 hours
Snowmelt
Accumulated snow melts rapidly → large water volume released quickly
Example: 1995 Yarm flood (Pennines snowmelt + rain)
Steep slopes
Mountainous areas: water flows downhill quickly → rapid river rise
Example: Lake District, Scottish Highlands
Impermeable geology
Granite, clay - water can't infiltrate → runs over surface
Example: Areas with boulder clay
Social Impacts
- • Deaths/injuries from drowning or being trapped
- • 1,000s displaced requiring emergency accommodation
- • Trauma, fear, stress, anxiety
- • Can't return home for months (drying, repairs)
- • Health issues from contaminated water, mold
- • Schools closed, education disrupted
Economic Impacts
- • Property damage: £20,000-100,000+ per home
- • Business disruption: shops/factories closed
- • Infrastructure damage: roads, bridges (£millions)
- • Agriculture: crops destroyed, livestock drowned
- • Insurance premiums rise dramatically
- • Property values fall in flood-prone areas
Environmental Impacts
- • Water pollution: sewage, oil, chemicals
- • Soil erosion: fertile topsoil removed
- • Habitat destruction: burrows flooded, nests destroyed
- • (Positive) Nutrient deposition: silt makes soil fertile
- • (Positive) Wetland creation: biodiversity benefits
- • (Positive) Groundwater recharge: replenishes aquifers
Key Statistics
2007 UK floods: £3.2 billion damage
1995 Yarm (River Tees): Town center flooded, defenses overtopped after 2 years
Average home flood damage: £20,000-100,000+
2020 England (Storm Dennis): £300M+ damage
Dams & Reservoirs
£50M-500MDam built across river valley. Water stored in reservoir. Controlled release through sluice gates regulates flow downstream.
Advantages
- + Very effective (completely controls flow)
- + Multi-purpose (hydropower, water supply, recreation)
- + Long lifespan (100+ years)
Disadvantages
- - Very expensive (£50M-500M)
- - Displaces people (valleys flooded)
- - Sediment trapped (starves downstream)
- - Habitats destroyed
Example: Kielder Dam, River North Tyne - £167M, 200 million m³ capacity
Embankments (Artificial Levees)
£1-5M per kmRaised banks built alongside river. Increases channel capacity so water contained at higher level.
Advantages
- + Allows floodplain use (agriculture, development)
- + Relatively cheap (£1-5M/km)
Disadvantages
- - If breached → catastrophic flooding
- - Maintenance needed (erosion, burrowing animals)
- - Can make flooding worse downstream
Example: River Thames, London - Victorian embankments (1860s)
Flood Relief Channels
£5-20MArtificial channel built parallel to river. Diverts excess water during floods. Rejoins river downstream.
Advantages
- + Protects settlements (water bypasses them)
- + Reduces peak flow
Disadvantages
- - Expensive (£5-20M)
- - Requires space (land purchase)
Example: Jubilee River, Maidenhead/Windsor - 11.6km, £110M, prevented £1B+ damage since 2002
Channel Straightening
VariesRemove meanders (straighten channel). Water flows faster → exits area quicker.
Advantages
- + Quick (short construction time)
- + Effective locally
Disadvantages
- - Increases flooding downstream
- - Destroys habitats (meanders are rich ecosystems)
- - Erosion increases (faster flow)
Example: River Skerne, Darlington - Straightened 1960s, later restored 1995
Location
- Region: North East England (Cumbria, County Durham)
- Source: Cross Fell, North Pennines (732m altitude)
- Mouth: North Sea at Teesmouth (between Hartlepool & Redcar)
- Length: 137km (85 miles)
- Drainage basin: 1,800 km²
- Direction: Flows east (Pennines to North Sea)
Physical Context
- Upper geology: Carboniferous limestone, Whin Sill (hard dolerite), millstone grit
- Lower geology: Bunter sandstone, pebble beds
- Rainfall: 1,200-2,000mm/year in Pennines (orographic)
- Relief: 732m at source to sea level
- Key tributaries: Greta, Lune, Balder, Leven, Skerne
Key Settlements
Upper course:
Cross Fell (source), Forest-in-Teesdale
Middle course:
Barnard Castle, Middleton-in-Teesdale
Lower course:
Darlington, Yarm, Stockton, Middlesbrough
1. Which erosion process involves rocks colliding and becoming smaller and rounder?
2. What type of erosion is dominant in the upper course of a river?
3. What landform is created when a waterfall retreats upstream?
4. On a meander, where does deposition occur?
5. What is the main advantage of soft engineering over hard engineering?
6. What is the height of High Force waterfall on the River Tees?