Presentation on Sediment Research Teagasc given by Daire Ó hUallacháin at Siltflux workshop

1. Sediment Research
Teagasc
Daire Ó hUallacháin
Daire.ohuallachain@teagasc.ie

2. Sophie Sherriff1,2,
Rowan, J.S.2, Melland, A.R.3, Fenton, O.1,, Jordan, P.4
Ó hUallacháin, D.1
1Teagasc, Johnstown Castle Research Centre, Wexford, Ireland
2School of the Environment, University of Dundee, Dundee, DD1 4HN, Scotland, UK
3University of Southern Queensland, Toowoomba, QLD, Australia
4School of Environmental Sciences, University of Ulster, Coleraine, Northern Ireland
Sediment Flux and Provenance

3. Agricultural Catchments Programme

4. Project outline
Quantification of
sediment flux
Validation of out-of-stream
turbidity measurement
Event scale sediment
responses
Soil loss
Sediment
fingerprinting
Calibration of turbidity
equipment
Field based soil loss
Caesium-137
Sediment in channel bed
storage
Sediment delivery ratio
Sources of sediment in three
agricultural catchments
Sub-catchment resolution
sediment fingerprinting
Uncertainty inclusive un-
mixing model development

5. Sediment flux
• Turbidimeters housed out-of-channel
• 10-min turbidity and discharge measurement
• T-SSC calibration dataset captured at baseflow
and during events
• Water samples processed for SSC
• Rating curves constructed

6. Sediment flux data
Average annual suspended sediment yield Frequency-distribution graph

7. Inter-annual variability
• Considerable inter-annual
variability
• Rainfall and discharge cannot
solely explain variability in
sediment yield
• Seasonal/event catchment
conditions are likely important
to dictate soil erosion/sediment
transport

8. Sediment fingerprinting
Source 1
fingerprint
Source 2
fingerprint
Source 3
fingerprint
Source 4
fingerprint
Geochemistry
Radionuclides
Magnetics
Isotopes
Colour
Sediment
sink
fingerprint
(mixture of
sources)
Erosion &
transport
Un-mixing
Source 1
Source 2
Source 3
Source 4
Source 1
30%
Source 2
5%
Source 3
20%
Source 4
45%

9. Sediment fingerprinting
Printed under License No. 6155 from the Ordnance Survey Ireland

10. Sample collection
Grassland soils Arable soils
Farm tracks Ditches
Road verges
Stream samples
Channel banks

11. Sample preparation and analysis
• Dried at <40°C
• Sieved to 125 µm
• Processed for mineral magnetics
• Radionuclide and geochemical
tracers
• Three parent sources determined
• Channel: channel banks, eroding
ditches
• Field: subsoils, topsoils, drain outlets
• Roads: road verges, tracks

12. Results
Lower Median Upper
Channel
banks
60.14 70.37 80.52
Fields 10.37 12.18 13.72
Roads 7.4 17.45 27.17
Lower Median Upper
Channel
banks
36.98 43.80 51.02
Fields 19.98 21.75 23.74
Roads 27.22 34.45 40.59
Lower Median Upper
Channel
banks
30.71 45.68 59.86
Fields 0.03 1.47 2.91
Roads 38.93 52.85 67.05

13. Results

14. Sustainable land use management for the conservation of the
Freshwater Pearl Mussel: sediment flux and provenance - KerryLIFE
EU LIFE+ Nature
Teagasc; NPWS, SKDP, DAFM, Coillte
Objectives
• Quantify the sediment delivery dynamics within FPM catchments
• Quantify and compare sediment flux across sub-catchments with different
land uses
• Quantify the rate, physico-chemical properties and residence time of fine-
sediment deposited within FPM channel bed habitats.
• Characterise quality of FPM in-stream habitats
• Quantify the contribution from sediment sources to sediment sinks.
• Assess the local impact of selected sediment mitigation measures
Impact
• A sediment provenance methodology with particular consideration to FPM
catchments featuring a mosaic of land-uses.
• Characterisation of river-bed sediments –sedimentation dynamics and
interplay between sediment supply & local hydromorphological conditions.
• Evaluation of selected sediment mitigation measures for the conservation
of FPMs.

15. Classifying drainage channels for sediment and phosphorus management
Shore et al. (2015) Agriculture Ecosystems and Environment. 199. 207 – 215.
Stream
Ditch – high slope
Ditch – moderate slope
Ditch – low slope
Outlet

16. Validation of interpreted phosphorus transfer pathways
Shallow groundwater
Mellander et al., ES&P 2012
Mellander et al., ES&T 2013
Deep groundwater
Quickflow
Interflow
Slowflow I
Slowflow II
Slowflow III

17. 1860 15µg/L
1940 15µg/L
2000 40µg/L
2010 30µg/L
Total P
Sediments as records of environmental change
O’Dwyer et al. 2013 Journal of Environmental Management, v124, 147-155.
1995 8kg/ha
2005 16kg/ha
2010 15kg/ha
Org P load

18. Impact
Mitigation measures
Future agri-environment schemes
Environmental policy
Water Framework Directive
Nitrates Directive
Cross Compliance
Common Agricultural Policy
Flood’s Directive
Sustainable farming
Future Biodiversity plans
Habitats Directive

19. Thank you
Daire.ohuallachain@teagasc.ie