This presentation was given as part of the EPA-funded Catchment Science and Management Course focusing on Integrated Catchment Management, held in June 2015. This course was delivered by RPS Consultants. If you have any queries or comments, or wish to use the material in this presentation, please contact catchments@epa.ie It is increasingly being recognised internationally that integrated catchment management (ICM) is a useful organising framework for tackling the ongoing challenge of balancing sustainable use and development of our natural resource, against achieving environmental goals. The basic principles of ICM (Williams, 2012) are to: • Take a holistic and integrated approach to the management of land, biodiversity, water and community resources at the water catchment scale; • Involve communities in planning and managing their landscapes; and • Find a balance between resource use and resource conservation ICM is now well established in Australia, New Zealand, and the United States. In Europe the ICM approach has been proposed as being required to achieve effective water and catchment management, and is the approach being promoted by DEFRA for the UK, where it is called the “Catchment Based Approach” (CaBA). The principles and methodologies behind ICM sit well within the context of the Water Framework Directive with its aims and objectives for good water quality, sustainable development and public participation in water resource management. In Ireland it is proposed that the ICM approach will underlie the work and philosophy in developing and implementing future River Basin Management Plans.

1. Load Apportionment
Which loads are dominant

2. Build Partnership
Create an ICM
Vision
Characterise the
Catchment
Undertake further
characterisation
Identify &
Evaluate Possible
Management
Strategies
Design an
Implementation
Programme
Implement the
River Basin
Management Plan
Measure Progress
and Make
Adjustments
Further Characterisation
• Loads are used for quantifying
pressures within a catchment
• Loads also assist in the further
characterisation of critical
source areas for these
pressures

3. Load vs Concentration
• Load is derived from Concentration x flow and is expressed as mass
per time
• The nutrient loading delivered to a water body drives its
productivity and can therefore be a more meaningful indicator
compared to concentration
• Concentration also has value in determining, for instance, eco-
toxicological effect, or whether levels can be considered normal or
are elevated

4. How do you measure Load & apportion
Load to Pressures?
• Investigative Monitoring
• OSPAR nutrient quantification tools (HARP-NUT)
• Use of models

5. WFD monitoring programme
Surveillance
• long term trends
• all quality elements
Operational
• record improvements due to
measures
• targeted quality elements
Investigative
• unpredicted water quality problems
or pollution events
• targeted quality elements
Rivers Surveillance Sites

6. Measuring pollutant concentrations

7. Measuring flow

8. Relating flow to water level
Stage(h)
Flow (cumecs)
Graph showing the connection between the water level elevation
(stage) at a cross-section and the corresponding flow.

9. Typical Catchment
Annual Total Phosphorus Loading
0
20
40
60
80
100
120
01-Jan-
01-Feb-
01-Mar-
01-Apr-
01-May
01-Jun-
01-Jul-0
01-Aug-
01-Sep-
01-Oct-
01-Nov-
01-Dec-
kgTPperday
0
1
2
3
4
5
6
7
8
9
10
Flow(m
3/
s)
TP load
Flow
Deenagh

10. 0
1
2
3
4
5
6
7
Monthly Fortnightly Weekly Actual
TPload(tonnesyear-1
)
Maximum estimate Minimum estimate Actual load
0
2
4
6
8
10
12
Monthly Fortnightly Weekly Actual
TPload(tonnesyear-1
)
Maximum estimate Minimum estimate Actual load
0
100
200
300
400
Monthly Fortnightly Weekly Actual
TONload(tonnesyear-1
)
Maximum estimate Minimum estimate Actual load
0
100
200
300
400
Monthly Fortnightly Weekly Actual
TONload(tonnesyear-1
)
Maximum estimate Minimum estimate Actual load
Daily auto-sampler data - sub-sample data at weekly, fortnightly monthly intervals
TP
TON
How often do you need to sample?
Courtesy Eleanor Jennings, TCD

11. Types of Error
Type I error: over-estimate load
…. could lead to substantial costs being unnecessarily imposed on
water users.
Type II error: under-estimate load
…. fail to identify risks of significant damage that could be averted.
Sampling
Cost
Sampling
Accuracy

12. Typical Catchment d/s of a large lake
Retention in the system is important!
0
200
400
600
800
1000
1200
01-Jan-
01-Feb-
01-Mar-
01-Apr-
01-May
01-Jun-
01-Jul-0
01-Aug-
01-Sep-
01-Oct-
01-Nov-
01-Dec-
kgTPperday
0
20
40
60
80
100
120
140
160
Flow(m3
/s)
TP
Flow
Flesk

13. Export Coefficients
• Export Coefficient = Load / contributing
catchment area
• Export coefficients can be calculated for each Lough
Leane Subcatchment:
– Clydagh Valley (dominated by forestry);
– Upper Lough Guitane catchment (sheep farming);
– Upper Deenagh catchment (dairy/dry stock).

14. Sub catchment loading

15. Source Apportionment – Lough Leane
Background
23%
Urban & Industry
15%
Agriculture
47%
Septic Tanks
12%
Forestry
3%
Background
Urban & Industry
Agriculture
Septic Tanks
Forestry

16. Where do you start if you have very little
monitoring data?
• The OSPAR Convention has developed guidelines
towards harmonised procedures for the quantification
of nutrient losses to the North-East Atlantic (HARP-NUT)
• There are 9 guidelines for producing annual catchment-
based figures for total discharges / losses / inputs of N
and P from point and diffuse sources
• Ensures harmonised & transparent approach to nutrient
reporting across OSPAR member countries

17. HARP-NUT Guidelines
• A selection of quantification methodologies is provided for each pressure;
from simple theoretical quantification to more sophisticated methods
based on monitoring information.
• Application of the HARP-NUT guidelines in Ireland:
– 1999 Screening Procedure for Irish Coastal Waters with regards to Eutrophication Status
(EPA, 1999);
– 1999 trial in the Lough Derg and Ree catchment (Murdoch, 1999);
– 2004 WFD Article V Characterisation Report (2005);
– 2008 OSPAR PARCOM Recommendation 88/2 Report;
– 2010 WFD Water Management Unit Action Plans;
– 2012 OSPAR PARCOM Recommendation 88/2 Report.

18. HARP-NUT Guidelines
• The sectors for which N and P loads are estimated in Ireland include:
– Waste Water Treatment Plants (WWTPs)
– Unsewered industries (industries licenced to discharge to surface water i.e. IPPCs
and LA Section 4s)
– Agriculture
– Foresty
– Urban areas
– Unsewered rural populations
• Background losses are also estimated
• Retention factors are applied
• The quantification of N and P losses at source are reconciled with N & P measurements

19. WWTPs - Guideline No. 4
Load = Population Equivalent x nutrient loading x
treatment reduction factor
Nutrient production figures
Total N = 9.0g person-1 day-1
Total P = 2.7g person-1 day-1
Level of Treatment N Reduction Factor P Reduction Factor
Raw 1.000 1.000
Preliminary treatment 0.900 0.900
Primary treatment 0.727 0.667
Secondary treatment 0.545 0.467
Additional nutrient removal 0.300 0.100

20. Unsewered Industry - Guideline No. 3
Load = 25% of max allowable discharge
i.e.
Load = 0.25 x (max flow x max nutrient concentration)

21. Agriculture - Guideline No. 6
Load = (Number of Livestock Units x Nutrient Production +
chemical fertiliser usage ) x nutrient loss factor
Livestock Type N production per LU P production per LU
Bulls 85 13
Dairy cows 85 13
Suckler cows 65 10
Cattle (0-1) 24 3
Cattle (1-2) 57 5
Cattle (>2) 65 10
Sheep 13 10
Nutrient Loss Factors
N loss factor = 0.20
P loss factor = 0.04
Livestock Units (LU)
1 grazing dairy cow = 1 LU
1 grazing lowland sheep = 0.2 LU

22. Forestry - Guideline No. 6
Load = area of forestry plantation x standard coefficient
N loss coefficient
(kg ha-1 annum-1)
P loss coefficient
(kg ha-1 annum-1)
Forestry 5.42 0.33
Woodland scrub 3.71 0.565

23. Urban Areas - Guideline No. 6
Load = area under urban cover x standard coefficient
N loss coefficient
(kg ha-1 annum-1)
P loss coefficient
(kg ha-1 annum-1)
Continuous urban fabric 5 1.4
Discontinuous urban fabric 5 0.86
Industrial areas 5 1.88
Construction sites 5 2.15

24. OSWWTS - Guideline No. 5
Load = non-sewered population x nutrient emission value
N emission value
kg person-1 year-1
P emission value
kg person-1 year-1
Septic tank 2.4 0.25
Septic tank remote 0.7 0.25

25. Background - Guideline No. 6
Load = Area x standard coefficient
N background runoff = 0.75 kg ha-1 annum-1
P background runoff = 0.05 kg ha-1 annum-1

26. Retention - Guideline No. 9
Factors applied to catchments upstream of lakes.
N retention = 0.1 of the predicted inflow loading
P retention = 0.24 of the predicted inflow loading

27. Load Reconciliation
• It is important to verify that the estimated N and P loadings at
source (source orientated approach) are realistic
• A verification exercise is therefore required by comparing the
estimated results with monitoring results (load orientated
approach) i.e. loads measured in the Riverine Inputs and Direct
Discharges (RID) Programme

28. Discussion on HARP-NUT Guidelines
• Does not take account of all sources of nutrients e.g. atmospheric deposition in
marine area, dumping at sea, unregulated industry, slurry spreading
• Some sectors are more poorly accounted for than others
• Background losses and retention are poorly accounted for
• Does not consider changes in loads during transport e.g. sedimentation,
mineralisation
• Does not reflect management practices
• As datasets improve, it will be possible to move toward using monitoring data to
quantify loads which is the preferred approach outlined in the HARP-NUT guidelines

29. Use of Models
Complexity of River Quality issues
• Rivers usually receive loads from numerous sources
• The decisions made at one location in the catchment to address point or diffuse
pressures can depend on the choices to be made at those upstream or downstream
• Water quality calculations can be complex and time consuming
• An attractive option is to provide an automatic method of doing all the water quality
calculations for an entire catchment in one go:
– Saves time;
– Allows for catchment-wide water quality management;
– Provides useful planning / decision making tool;
– Prioritisation of water quality issues.

30. SIMCAT model
Mixing of a discharge with a river is described by the
Mass Balance Equation

31. SIMCAT looks at the distribution of the flows and concentrations when
determining the mass balance equation
SIMCAT model

32. Agricultural Models at Catchment Level
There are a number of Nutrient Loss Models available to estimate the nutrient losses
from diffuse agricultural sources in use by EU Member States. The following where
evaluated by the EuroHARP Project
NL-CAT N,P
REALTA P
SWAT N,P
EvenFlow N
NLES-CAT N
TRK N,P
NOPOLU N,P
Moneris N,P
The models generally require detailed datasets to be effective

33. Agricultural Bye-Laws introduced under the
Water Pollution Act within High Risk Areas
by
Cavan Co Co
Westmeath Co Co
Offaly Co Co
North Tipperary Co Co
Source apportionment
In Action