This document summarizes suspended sediment measurements from several Irish rivers. It discusses suspended sediment concentrations and fluxes found in Irish rivers based on published data. It also describes suspended sediment monitoring conducted as part of the Siltflux project on several catchments, finding suspended sediment concentrations up to 900 mg/l and most sediment being transported during high flow periods in winter months. Suspended sediment characteristics and impacts are also briefly discussed.

1. Suspended Sediment Measurements
in Irish Rivers (summary)
Anna Rymszewicz, John O’Sullivan, Michael Bruen,
Jonathan Turner, Elisabeth Conroy, Mary Kelly-Quinn, Damian Lawler
SILTFLUX Worshop No 3
February 2016

2. 1. Suspended Sediment (SS) Fluxes and Suspended
Sediment Concentrations (SSC) in Ireland –
overview of published data
2. SS measurements: Siltflux project
• Discussion of SS transport characteristics and SS levels
Presentation Overview

3. • SSC - Suspended Sediment Concentration (mg/l)
• TSS - Total Suspended Solids (mg/l)
• SSF - Suspended Sediment Flux (Load) (tonnes/year)
• SSY- Suspended Sediment Yield (tonnes/ha/year)
Suspended Sediment Measurements
0
200
400
600
0 100 200 300 400TSS(mg/l)
Turbidity (NTU)

4. (Vanmaercke et al., 2011)
European Sediment Yields
GS - Gauging Stations
R - Reservoir

5. SSY in Ireland: 2.1 - 48.4 tonnes km-2 year-1
SSY in Ireland
Catchment Area
(km2)
Sediment yield
(t km-2 year-1)
Reference
Corduff 3.34 6.07 - 22.28 Sherriff et al., 2015
Mount Stewart 7.52 6.7 Thompson et al., 2014
Timoleague 7.9 3.95 - 14.92 Sherriff et al., 2015
Dunleer 9.4 13.5 - 41.8 Melland et al., 2010, Sherriff et al., 2015
Castledockrell 11 2.11 - 23.1 Melland et al., 2010, Sherriff et al., 2015
Ballycanew 11.4 6. 65 - 48.39 Sherriff et al., 2015
Dripsey 15.24 9.8 - 16.1 Kiely et al., 2007
Glenamong 17.91 16 May et al., 2005
Mattock 20.96 44 Thompson et al., 2014
Clarianna 29.8 8.5 Kiely et al,. 2007
The Oona 84.5 29 - 41 Kiely et al., 2007
Owenabue 103 25.6 Harrington & Harrington 2013
Bandon 424 14.2 Harrington & Harrington 2013

6. Max SSC reported:
SSC in Ireland
• Mean annual SSCs < FFD threshold of 25mg/l,
• FFD threshold exceedance occurred 1-11% sampled time
(Sherriff et al., 2015), 8.3%, 17.8% (Thompson et al., 2014)
Land Use Catchment max SSC (mg/l) Reference
Pasture CIT catchments: 837 - 979 mg/l
ACP catchments: 419 - 1020 mg/l
Harrington & Harrington 2013
Sherriff et al., 2015
Arable ACP catchments: 224 - 2141mg/l Sherriff et al., 2015
Forestry Increased SSC after clearfelling
Peak SSC increased from 88mg/l
pre-windrowing to 502mg/l during
windrowing operations
Rodgers et al., 2011
Clarke et al., 2015

7. • Freshwater pearl mussel
• Fish spawning grounds
• Transport of nutrients, pollutants
Sediments levels – Irish Impacts
Suspended sediment in peatland dominated River
Sanginjoki (Finland) (Marttila and Klove, 2015)
Glenamong (18.21 km2),
77% upland peat, 23% forestry
• 6.2 tonnes POC km2 year (2010),
• 13.6 tonnes POC km2 year
(Oct 2010 to Set 2011)
(Ryder et al., 2014)
Photo source: IRD Duhallow Life Project
• High potential for organic particulate matter

8. Siltflux Catchments
CAMLIN
• 31 Typology
• Size: 92.1 km2
• 86.45% Pasture
SLANEY
12 Typology
• U/S: 47.3 km2
23% pasture
D/S: 207.84 km2
53.5% pasture
GLYDE
31 Typology
• D/S: 345.27 km2
21.6% arable land
(57% between U/S lakes and
D/S monitoring point)
CLODIAGH
31 Typology
U/S: 26.85 km2,
15.7% pasture
D/S: 116.52 km2,
51% pasture
URRIN
12 Typology
U/S 47.8 km2
D/S 115.1 km2
41% arable land

9. SSF measurements
0
200
400
600
0 100 200 300 400
TSS(mg/l)
Turbidity (NTU)

10. Flow Estimation using HECRAS derived
Channel Survey-1

11. Completed survey of Gibstown (Slaney) and Kilgortin (Clodiagh)
for modelling of rating relationship
Flow Estimation using HECRAS derived
Channel Survey-2

12. Flow Estimation using HECRAS derived
rating relationship - 1
1000992
986.*
980
977.*
974
972.*
970955
941.*
927.*
919.2*
917.6*
916.*
914.4*
912.8*
911.2*
909.6*
908.*
906.4*
904.8*
903.2*
901.6*
900
Clodiaghds Plan: Plan 01 10/11/2015
Legend
Ground
BankSta
Ground

13. Flow Estimation using HECRAS derived
rating relationship - 2
1000992
986.*
980
977.*
974
972.*
970955
941.*
927.*
919.2*
917.6*
916.*
914.4*
912.8*
911.2*
909.6*
908.*
906.4*
904.8*
903.2*
901.6*
900
Clodiaghds Plan: Plan 01 10/11/2015
Legend
WS PF 9
Ground
BankSta
Ground

14. 1000992
986.*
980
977.*
974
972.*
970955
941.*
927.*
919.2*
917.6*
916.*
914.4*
912.8*
911.2*
909.6*
908.*
906.4*
904.8*
903.2*
901.6*
900
Clodiaghds Plan: Plan 01 10/11/2015
Legend
WS PF 7
Ground
BankSta
Ground
Flow Estimation using HECRAS derived
rating relationship - 3

15. 1000992
986.*
980
977.*
974
972.*
970955
941.*
927.*
919.2*
917.6*
916.*
914.4*
912.8*
911.2*
909.6*
908.*
906.4*
904.8*
903.2*
901.6*
900
Clodiaghds Plan: Plan 01 10/11/2015
Legend
WS PF 3
Ground
BankSta
Ground
Flow Estimation using HECRAS derived
rating relationship - 4

16. Flow Estimation using HECRAS derived
rating relationship - 5
1000992
986.*
980
977.*
974
972.*
970955
941.*
927.*
919.2*
917.6*
916.*
914.4*
912.8*
911.2*
909.6*
908.*
906.4*
904.8*
903.2*
901.6*
900
Clodiaghds Plan: Plan 01 10/11/2015
Legend
WS PF 1
WS PF 2
WS PF 3
WS PF 4
WS PF 5
WS PF 6
WS PF 7
WS PF 8
Ground
BankSta
Ground

17. HECRAS derived rating relationship - 6
0 2 4 6 8 10
8.2
8.4
8.6
8.8
9.0
9.2
9.4
9.6
Clodiaghds Plan: Plan 01 12/11/2015
u/s boundary
Q Total (m3/s)
W.S.Elev(m)
Legend
W.S. Elev
Clodiagh d/s

18. Siltflux SSY estimates and SSC –
preliminary results
Camlin
SSC up to 200-300
Max SSC ~857 mg/l
Glyde
Low SSC:
40-50mg/l,
Up to ~150 mg/l
Slaney
SSC ~200/300mg/l
Clodiagh
~ Max SSC 585 mg/l
Urrin
SSC up to 300-400mg/l
Max SSC ~900 mg/l

19. Sediment Transport - Slaney
• Majority of sediment transported in short period of time
• Between 16th Dec – 24th Feb. (in 19.5%of time) 83.4% of sediment load
May 2013 – May 2014

20. Sediment Transport - Slaney
• Sediment peak usually preceding event peak
• Steeper sediment rise on the rising limb

21. Sediment Transport - Camlin
Camlin Oct 2014 - Oct 2015
• Nov-Jan – 53% of Total SSF
• Different sediment levels for the same magnitude events
Month Oct Nov Dec Jan Feb March Apr May Jun July Aug Sept Oct
% SSF 7.1 26 13 14.2 8.3 8.4 5.5 7.5 0.6 1 7.7 0.8 0.1

22. Sediment Transport - Glyde

23. • Relatively low SSY in comparison to European levels
• Inter-annual variability of SSY
• Mean annual SSC not exceeding 25mg/l, however high SSC recorded
during the storms for all land uses (published Irish data)
• Majority of sediment transported in a short period of year
• Different sediment levels between same magnitude events (complex
relationship between sediment exhaustion and supply)
• Sediment peak usually preceding discharge peak (positive sediment
hysteresis) suggesting source limited sediment transport
Sediment transport characteristics -
summary

24. • Clarke, J., et al. (2015) The effect of forest windrowing on physico-chemical water quality in Ireland. Science of
the Total Environment, 514, 155-169.
• Harrington, S. T. & Harrington, J. R. (2013) An assessment of the suspended sediment rating curve approach
for load estimation on the Rivers Bandon and Owenabue, Ireland. Geomorphology, 185, 27-38.
• Kiely, G., et al. (2007) Eutrophication from agricultural sources (Phosphorus and Nitrogen). Sub-project Soil
and Phosphorus: Catchment Studies. EPA, Ireland (Ref. 2000–LS–2.1.1a–M1).
• May, L., et al. (2005) Modelling soil erosion and transport in the Burrishoole catchment, Newport, Co. Mayo,
Ireland. Freshwater Forum, 23, 139-154.
• Marttila, H. and Kløve, B. (2015) Spatial and temporal variation in particle size and particulate organic matter
content in suspended particulate matter from peatland-dominated catchments in Finland. Hydrological
Processes, 29, 1069-1079.
• Melland, A.R., et al. (2012) Stream water quality in intensive cereal cropping catchments with regulated
nutrient management. Environmental Science & Policy, 24, 58-70.
• Rodgers, M., et al. (2011) Suspended solid yield from forest harvesting on upland blanket peat. Hydrological
Process, 25, 207-216.
• Ryder, E., et al. (2014) Identifying the role of environmental drivers in organic carbon export from a forested
peat catchment. Science of the Total Environment, 490, 28-36.
• Sherriff, S. et al. (2015) Identifying the controls of soil loss in agricultural catchments using ex situ turbidity-
based suspended sediment monitoring. Hydrology and Earth System Sciences , 12, 2707-2740.
• Thompson, J., et al. (2014) Assessing suspended sediment dynamics in relation to ecological thresholds and
sampling strategies in two Irish headwater catchments. Science of the Total Environment, 468-469, 345-357.
• Vanmaercke, M., et al. (2011) Sediment yield in Europe: Spatial patterns and scale dependency.
Geomorphology, 130, 142-161.
References