Final workshop
Twinning on development of
modelling capacity to support
water quality monitoring in
Latvia
Modelling: rationales and
selection
Photo Lake Övre hammardammen, Fredrik Ejhed
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Resolution ?
Purpose ?
•Load and source apportionment
•Scenario of change
•Investigative modelling
•Substances
– temporal and spatial
•Daily drive data but annual results
•Dynamic results needed in lakes
and coastal processes
•Spatial resolution – time and cost
proportional
•WFD demand both high spatial resolution
and overview
•Monitoring data dependence
Models ?
Experience ?
Data ?
•Requirements
•Availability
•Model tested for similar conditions
•User experience
•User interface
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Freeware vs commercial -aspects
 Access
 Support
 Developments
 Modules - Package
 Cost
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Model concepts
High
Physical
Model type
Daily simulations of flow
and solute concentrations
Methods differ profoundly in their
complexity, level of process
representation and data
requirements
Level of complexity
Empirical
Annual predictions based on
export coefficients
Low
Rewritten from EUROHARP documentation
• Combination of models above
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Model concepts
Limitations and advantages
Physical
Advantages
Limitations
•Process descriptions
•Scenarios possibilities
•Expert user
•High data requirements
•Timeconsuming
•Low data requirements
•Simple models
•Few scenario possibilities
•Valid only for model range
Model type
Empirical
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Calibration of models
 The conceptual and processbased model is calibrated
using monitoring data
Fig. Total nitrogen concentration before and after
calibration of soil retention, Skivarpsån Sweden, model for
HELCOM PLC4 and WFD
 Empirical models e.g. regression analysis are only valid
within the data range used
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Results –weakest link rule
 A good model need good driving data
Ex. problems with faulty point source coordinates in an
inlet watercourse to lake Vättern in Sweden, model for
HELCOM PLC-4 and WFD. Total nitrogen concentrations
vs. time.
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Purpose and resolution
Latvia
 WFD demands high resolution for
programmes of measures as well as
overview for characterisation.
 Eutrophication
– Load and source apportionment
– Scenario of change
 Priority hazardous substances
– Load and chemical fate
– Dispersion
– Ecological status
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Monitoring vs. Modelling
 Monitoring at strategic sites
 Regionalised data – WFD
typology
 Modelling gives overview
 Modelling gives physical
processes
 Models needed to plan measures
 No model without monitoring
data
Monitoring sites in Sweden used for
WFD and HELCOM PLC-4
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Hydrological modelling HBV
HBV
230 stations for calibration
140 stations for validation
timesplit validation also
6 Parameter regions for
calibration of HBV hydrology
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Models to meet Latvian purpose and
resolution – diffuse sources of
eutrophication
 EUROHARP models for eutrophication
– EH evaluated models to harmonize reporting procedures
on diffuse sources.
– Only 2 out of the nine EH models evaluated very
suitable for scenario calculations and hydrology,
TRK and SWAT
– TRK and SWAT have been applied with good results in
Sweden with similar climate as in Latvia.
 Alternative eutrophication model
– INCA, a good alternative due to a modest need of input
data, single interface and a complete catchment model.
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Selected models - Eutrophication
 Hydrology models
Because of the importance of process and models selected
due to their difference in complexity:
– SCS
– HBV
 Water quality models
Because of the varying need of high resolution in
hydrology environment
– CE-QUAL-W2
 Catchment models
Because of the importance of diffuse and point sources
and the models ability to perform scenario calculations
– TRK
– SWAT
– INCA
 Source apportionment and scenario tools
Because of the importance of presentation and user
friendly tests of scenarios of change
– WATSHMAN
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Models comparison
Models
SCS
HBV
CEQUALW2
TRK
SWAT
INCA
WATSHMAN
Modest data
requirements
Y
Y
N
Y
N
Y
Y
High time resolution
N
Y
Y
Y
Y
Y
Y
High spatial
resolution
Y
Y
Y
Y
Y
Y
Y
Processbased
conceptual model
N
Y
Y
Y
Y
Y
N
Calibration data
required
N
Y
Y
Y
Y
Y
N
Scenario possibilities
N
Y
Y
Y
Y
Y
Y
Complete catchment
model
N
N
N
Y
Y
Y
Y
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Models comparison - continue
Models
SCS
HBV
CEQUALW2
TRK
SWAT
INCA
WATSHMAN
Distributed
Y
Y
Y
Y
N
Y
Y
(semi)
(fully)
(semi)
(semi)
(semi +)
(semi)
Time consuming
N
Y
Y
Y
Y
Y
N
Single interface
N
Y
Y
N
Y
Y
Y
Exchangeable
submodels
N
Y
-
Y
N*
-
Y
Applied for
national
assessments
-
Y
-
Y
-
-
N
Applied in
Northern Europe
Y
Y
Y
Y
Y
Y
Y
Non-Expert user
Y
N
N
N
N
N
Y
Freeware
Y
Y
Y
Y
Y
Y
Y
*
-
some process submodels can be chosen in a scrollist and some can be exchanged
have not been verified
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626
Priority hazardous substances
Models and concept
 Decision support system – SOCOPSE.se
Recommendation of concept:
 Chemical fate modeling – fugacity approach
 Screening monitoring
 MFA (Material Flow analysis) and LCA (Life Cycle
Analysis)
 QSAR modeling – for chronic toxicity and physical data
for new substances
 OMEGA for ecological status
 Fully distributed hydrological model for dispersion in
water environment
Twinning water quality modelling in Latvia
Helene Ejhed, 20070626