Sediment pollution from agricultural land: Sources, pathways and mitigation Mike Palmer Paul Quinn,

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Sediment pollution from agricultural land
Sources, pathways and mitigationMike
PalmerPaul Quinn, Jennine Jonczyk, David Rimmer
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Background
While extreme soil erosion in the UK is rare,
there is a pressing need for policy intervention
and better understanding of the processes
involved in aquatic sediment pollution
(Boardman, 2002). Particulate matter a major
vector of pollutants e.g. 90 of P flux in
rivers and lakes in Europe and N. America may be
associated with suspended sediment (FAO, 1996).
Managing pollution by managing runoff?

• FAO, 1996. Control of water pollution from
  agriculture - FAO irrigation and drainage paper
  55.
• Boardman, J 2002. The need for soil conservation
  in Britain revisited. Area 34 419-427.

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Project

• What are the sources and pathways of sediment
  pollution?
• What are the best means of control?
• Fitness for purpose
• Value for money
• Acceptability to farmer
• Field scale (Paradise Field, Cockle Park Farm)
• Farm scale (Nafferton Farm)
• Small catchment scale (Belford Burn)

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Nafferton Farm experimental catchment
Catchment size 65 ha Mixed cereal/dairy pasture
Slowly permeable soils Tile drainage
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Trial mitigation features
Sediment trap and P filter
Live willow dam
Wetland
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30 April 2008
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Sediment sources
Runoff from arable land
Runoff from pasture
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Runoff from tracks/hardstandings
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Sediment sources
Tile drains
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30/04/2008 Sediment trap
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30/04/2008 Sediment trap
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30/04/2008 Sediment trap
18 hour event period Sediment input 650.2
kg Sediment output 150.0kg Sediment capture
398.8 kg (77)
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30/04/2008 Sediment trap
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30/04/2008 Wetland
High flow remobilises trapped sediment
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Nafferton conclusions

• Majority of sediment mobilised during runoff
  events.
• Sediment can be trapped efficiently during
  events.
• Removing sediment has a large impact on nutrient
  loads.
• Sediment should be captured upstream of chemical
  and biological treatments.

But is prevention better than cure?......
Redesigned sediment trap
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Sediment source fingerprinting
Channel banks
Surface soil
Tile drains
Track runoff
Outlet sediment analysis
Source material analysis
Fingerprint parameter selection (Discriminant
function analysis)
Multivariate mixing model
Sediment source apportionment
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Cockle Park drainage experiment

• 3 treatments
• Conventional till
• Direct drill (min. till)
• Broadcast (zero till)

100 m

• Discharge monitoring
• Flow interval sampling

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Belford Burn Catchment area 6 km2 NVZ
status CSF area status Budle Bay NNR, SSSI
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• What are the sources of sediment?
• Different land uses
• Surface and subsurface pathways
• Can runoff control structures be truly
  multi-functional?