Presentation given by Joe Harrington, Cork Institute of Technology,at the workshop on Sediment Fluxes in Irish Rivers (Siltflux Workshop) = 28/10/14, UCD, Dublin 4

1. Sediment Research on the Rivers Bandon and
Owenabue, Ireland
Dr. J. Harrington
Cork Institute of Technology
Presented at SILTFLUX Workshop, UCD
28th October 2014

2. Outline of Presentation
• Introduction
• Study Catchments and Characteristics
• Data Collection Programme
• Sediment Fluxes and Yields
• Storm Based Events
• Nutrient Transport

3. Introduction
• Sediment Research has been underway at Cork Institute of
Technology for the past decade
• The focus has been on the nearby Rivers Bandon and
Owenabue
• The research work has studied suspended sediment
concentrations and loadings based on a field sampling and
continuous turbidity monitoring programme

4. Study Catchments

5. Study Catchments – Land Use
1
2
3
4
5
6
7
8
9
Forestry
Quarry
Urban Area
Rain Gauge
Hydrometric Station

6. Study Catchments - Soils
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Bandon Catchment
Owenabue Catchment
Acid Brown Earths, Brown Podzolics
Lithosols, Regosols
Surface /ground water gleys
Peaty gleys
Podzols
Variable
Blanket Peats
Made/Built Land
Water/Lake (including reservoirs)

7. River Bandon Catchment

8. Parameter Detail Parameter Detail
River Details: Station:
Catchment Bandon
Station Catchment
Area
424 km-2
Catchment Area 608 km-2 Length to Station 52.55 km
River Length 77 km Station Type Data Logger & Turbidity Probe
Altitude at source 320m OD Body Responsible Office of Public Works & CIT
Average Slope 4.16 m km-1 (from OS maps) Co-ordinates 51.74N, -8.68W
Average Flow Rate 15 m³ s-1 Staff Gauge Zero 6.94 m O.D.
Annual Average Rainfall 1207 mm/year (Cork Airport) Records Available 1975 - Date
Land Use Tillage, pasture, forestry, urban Turbidity Data 2010 - date
River Bandon – Summary Data

9. River Bandon Catchment – Some Information
• Relatively large sized catchment in an Irish context (608 km2)
• Primarily agricultural 94% (tillage and pasture)
• Prone to flooding
• Distinguished by engineered works on stretches
• Features a number of special areas of conservation (SAC)
• Exhibits a range of levels of water quality
• Features both suspended and bed load transport
• Dredging undertaken through the town of Bandon (post-2010)
• River improvement works proposed for 2015 and 2016
• River discharge to Kinsale Estuary

10. River Bandon – Data Collection
Manual Sampling Programme
At the Curranure Hydrometric Station
Samples tested for:
Suspended Sediment Concentration (SSC)
since 2004 and turbidity since 2007
Range of Nutrient Parameters
- Nov. 2009 to 2012
Additional suspended sediment and bed
sediment samples have been collected at a
number of locations along the river since
April 2012.
Automatic sediment sampler installed in
September 2014
Continuous Monitoring Programme
Turbidity data at 15 minute resolution
(February 2010 – date)
Campbell Scientific OBS 3+ probe
River stage/flow rate data at 15 minute
resolution

11. River Owenabue Catchment

12. Parameter Detail Parameter Detail
River Details: Station:
Sub-Catchment (of the
Lee)
Owenabue
Station Catchment
Area
103 km-2
Sub-Catchment Area 105 km-2 Length to Station 19.05 km
River Length 22.71 km Station Type Data Logger & Turbidity Probe
Altitude at source 110m OD Body Responsible Office of Public Works & CIT
Average Slope 6.34 m km-1 (from OS maps) Co-ordinates 51.82N, -8.42W
Average Flow Rate 2.294 m³ s-1 Staff Gauge Zero 11.29 m O.D.
Annual Average Rainfall 1207 mm/year (Cork Airport)
Water Level Records
Available
1956 - Date
Land Use Tillage, pasture, forestry, urban Turbidity Data 2009 - Date
River Owenabue – Summary Data

13. River Owenabue – Some Information
• A smaller scale catchment (105 km2)
• Primarily agricultural (97%) - tillage and pasture
• Moderate to poor water quality status
• Catchment hill slopes are quite steep with quick response to rainfall
• River discharge to Cork Harbour via town of Carrigaline

14. River Owenabue – Data Collection
Q = 13.6 m3 s-1 (Peak Flow of Event)
SSC = 123 mg L-1 (4 hours after peak)
Manual Sampling Programme
At the Ballea Bridge Upper Station
Samples tested for:
Suspended Sediment Concentration (SSC) since
2004 and turbidity since 2007
- to 2012
Range of Nutrient Parameters
- 2007 to 2012
Continuous Monitoring Programme
Turbidity data at 15 minute resolution
(Sept. 2009 – date)
Campbell Scientific OBS 3+ probe
River stage/flow rate data at 15 minute
resolution

15. SSC – Turbidity Relationships
1
R² = 0.9646
0
20
40
60
80
100
120
140
0 20 40 60 80
SSC(mgLˉ¹)
Turbidity (NTU)
(a) R² = 0.8709
0
100
200
300
400
500
600
700
0 100 200 300 400 500SSC(mgLˉ¹)
Turbidity (NTU)
(b)

16. Sediment Flux Analysis
Ls= 𝑸 𝒕 𝑺𝑺𝑪 𝒕 dt
t2
t1
where
Ls = load over a time period (t2 - t1),
Qt = flow rate at time t
SSCt = suspended sediment concentration at time t
Ref: Harrington, S.T., Harrington, J.R., ‘An assessment of the suspended
sediment rating curve approach for load estimation on the Rivers
Bandon and Owenabue, Ireland’, Geomorphology 185 (2013) 27-38.

17. Monthly Suspended Sediment Fluxes
0
200
400
600
800
1000
1200
1400
1600
1800
SuspendedSedimentLoad(tonnes)
0
200
400
600
800
1000
1200
1400
1600
1800
SuspendedSedimentLoad(tonnes)

18. Suspended Sediment Flux and Yield
SS Flux (tonnes/year) SS Yield (tonnes/ha/year)
Feb. ’10 –
Feb. 11
Feb. ’10 –
Feb. 12
Feb. ’10 – Feb.
11
Feb. ’10 –
Feb. 12
River Bandon 6012 4128 0.142 0.097
SS Flux (tonnes/year) SS Yield (tonnes/ha/year)
Sept. ’09 –
Sept. 10
Sept. ’09 –
Sept. 10
Sept. ’09 –
Sept. 11
Sept. ’09 –
Sept. 11
River
Owenabue
2636 1822 0.256 0.177

19. Storm Based Events
• Disproportionate delivery of suspended sediment flux on
infrequent high flow events
• Approximately 75% of the suspended sediment load is
transported on flow rates above the 10% exceedance level.
• Storm events identified and analysed
• Suspended sediment rating curves analysed (high degree of
variability found in the Q-SSC relationship)

20. Storm Based Events
0
20
40
60
80
100
120
0
10
20
30
40
50
60
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
AverageDailySSF(tonnes)
AverageDailyDischarge(106m³)
Avg. Daily Q
Avg. Daily SSF
0
10
20
30
40
50
60
70
80
0
5
10
15
20
25
30
35
40
45
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
AverageDailySSF(tonnes)
AverageDailyDischarge(106m³)
Avg. Daily Q
Avg. Daily SSF

21. Storm Based Events – River Bandon
0
20
40
60
80
100
120
140
0
20
40
60
80
100
120
SSC(mgLˉ¹)
FlowRate(m³sˉ¹) Event 6
Flow Rate
SSC
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120
SSC(mgLˉ¹)
Flow Rate (m³ sˉ¹)
Event 6Peak 1 CL
Peak 2 CL
0
5
10
15
20
25
0
10
20
30
40
50
60
SSC(mgLˉ¹)
FlowRate(m³sˉ¹)
Event 8
Flow Rate
SSC
0
5
10
15
20
25
0 10 20 30 40 50 60SSC(mgLˉ¹)
Flow Rate (m³ sˉ¹)
Event 8Peak 1 CL
Peak 2 CL
Peak 3 CL

22. Storm Based Events – River Owenabue
0
50
100
150
200
250
300
350
0
2
4
6
8
10
12
14
16
18
SSC(mgLˉ¹)
FlowRate(m³sˉ¹) Event 3
Flow Rate
SSC
0
50
100
150
200
250
300
350
0 5 10 15 20
SSC(mgLˉ¹)
Flow Rate (m³ sˉ¹)
Event 3Peak 1 CL
Peak 2 CL
0
100
200
300
400
500
600
700
0
2
4
6
8
10
12
14
SSC(mgLˉ¹)
FlowRate(m³sˉ¹)
Event 12
Flow Rate
SSC
0
100
200
300
400
500
600
700
0 2 4 6 8 10 12 14
SSC(mgLˉ¹)
Flow Rate (m³ sˉ¹)
Event 12
Peak 1 CL

23. Nutrient Transport
• Dissolved and particulate nutrient behaviour investigated
• Wide variability in nutrient concentrations
• Discharge and SSC influence concentrations
• Turbidity found to be a suitable surrogate for some phosphorous
parameters (TP and PP) but nitrogen parameters were not well correlated
Ref: Harrington, S. T. and Harrington, J. R.: Dissolved and particulate nutrient
transport dynamics of a small Irish catchment: the River Owenabue, Hydrol.
Earth Syst. Sci., 18, 2191-2200, doi:10.5194/hess-18-2191-2014, 2014.

24. Acknowledgements
• Funding Sources
IOTI Technological Sector Research Programme
Office of Public Works
Byrne Looby PHMcCarthy
• River Data
Office of Public Works
EPA
• Postgraduate Research Team
Sean Harrington, James Hickey, John Gamble, Kevin Motherway,
John Clancy