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| Installation & Copyright | About the GREAT-ER model | Running GREAT-ER | Creating new catchments | Results & Interpretation | Miscellaneous | |
About GREAT-ER model
Q: How does GREAT-ER compare from other water quality models for rivers?
Q: Is the model adapted for diffuse sources?
Q: Is the model adapted for intermittent discharge?
Q: What kind of data are needed to build a GREAT-ER application?
Q: Can I make a GREAT-ER application in my region?
Q: Where can I find documentation on the mathematical models for chemical fate?
Q: Where can I find more information on the Simpletreat 3.0 wastewater treatment model?
Q: Where can I find information on the hydrological modelling with GREAT-ER?
Q: What kind of simulation model is used?
Q: Has the GREAT-ER model been validated?
Q: How do I set up a validation campaign for a GREAT-ER catchment?
Q: Has an uncertainty analysis been performed on the GREAT-ER model? What are the main parameters driving the model results?
Q: What is the difference between PECinitial and PECcatchment calculated by GREAT-ER and PEC values defined in the EU Technical Guidance Documents?
Q: How does GREAT-ER compare from other water quality models for rivers?
A: The niche of GREAT-ER is the simulation of the fate of (organic) chemicals discharged from point sources into rivers. It does not model classical water quality parameters such BOD, DO, Nitrogen, Phosphorous or chlorophyll concentrations. For the latter purpose, excellent other models are available.
Q: Is the model adapted for diffuse sources?
A: For the moment, the model is not adapted for diffuse sources, but this addition is envisaged as part of the CEFIC-LRI program. Nevertheless, in some cases, diffuse sources can be simulated as multiple point sources.
Q: Is the model adapted for diffuse sources?
A: No, the model is built for point sources and continuous discharges (wide dispersive uses).
Q: What kind of data are needed to build a GREAT-ER application?
A: Various data types are used by GREAT-ER. The data description and structure are presented at pages 28-45 of the GREAT-ER 1.0 Technical Manual for further information (568 Kb).
Q: Can I make a GREAT-ER application in my region?
A: Yes, in principle the model can be applied on any river basin. The data-availability will need to be evaluated case-by-case.
Q: Where can I find documentation on the mathematical models for chemical fate?
A: These models are presented in the Technical Documentation GREAT-ER Chemical Fate Models (263 Kb). For further information, read the #3 contribution to GREAT-ER (Boeije et al., 1997, Wat. Sci. Technol 36, 251-258; list of publications (11 Kb)).
Q: Where can I find more information on the Simpletreat 3.0 wastewater treatment model?
A: You can read the publications of Struijs et al. (1991, Water Research, 25(7): 891-900), Struijs (1996, RIVM Report nr. 719101025 Nat Institute of Public Health and environmental Protection, The Netherlands) or the EU Technical Guidance Documents for chemical risk assessment.
Q: Where can I find information on the hydrological modelling with GREAT-ER?
The models used for the estimate of river flow and flow velocities are presented in the Appendix B (pages 70-86) of the GREAT-ER User Manual (1557 Kb) and in the GREAT-ER working note nr. 5 (1508 Kb).
Q: What kind of simulation model is used?
A: The GREAT-ER model performs a stochastic Monte Carlo simulation on top of a set of deterministic models. A large number of shots, which are discrete samples from the distributed dataset, are generated. For each of these shots, the deterministic model is called and the result is a lognormal distribution of the results from each individual shot. Therefore, GREAT-ER is a tool for probabilistic exposure assessment and the system can show any desired percentile of the distribution.
Q: Has the GREAT-ER model been validated?
A: Validation or 'evaluation' of the GREAT-ER model is an essential element of the project. To evaluate the accuracy of GREAT-ER 1.0, 2-year monitoring programmes were conducted in the four UK catchments (Yorkshire), in Italy (Lambro) and in Germany (Itter). Over 2000 river water and over 600 waste water treatment effluent samples were analysed for the surfactant LAS and for Boron. For further information see this web site. For review, read the contributions #2, #5, #6 and #10 to GREAT-ER (list of publications (11 Kb)).
Q: How do I set up a validation campaign for a GREAT-ER catchment?
A: Experimental model validation is a research topic on its own, but one of the basic principles should be that the monitoring strategy is in accordance with the philosophy of the model. For GREAT-ER, it means e.g. that samples should be taken over a period covering different hydrological conditions (dry, wet, normal) in the river basin, typically over one year or more. For further information on validation campaign, please read e.g. the following works: the master thesis (1269Kb) and the phD thesis of Carsten Schulze; and, Rupel validation report.
Q: Has an uncertainty analysis been performed on the GREAT-ER model? What are the main parameters driving the model results?
A: For uncertainty analysis, a first attempt was made by Galoch et al. (1998). We know that the model is particularly sensitive to the chemical input flow/dilution parameters, follow by chemical decay rate and other parameters.
Q: What is the difference between PECinitial and PECcatchment calculated by GREAT-ER and PEC values defined in the EU Technical Guidance Documents?
A: Yes, PECinitial is conceptually similar to the PEClocal as defined by EU Technical Guidance Documents, although its calculation is different. PECcatchment is a new concept, although there is some conceptual analogy with the PECregional in the EU Technical Guidance Documents. See pages 28-32 of the GREAT-ER User Manual (1557 Kb) or the #8 contribution to GREAT-ER (Boeije et al., 2000, Chemosphere, 40, 255-265) for more details.