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Is Lake Vänern well mixed?: A statistical procedure for selecting model structure and resolution
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
2004 (English)In: Journal of Great Lakes research, ISSN 0380-1330, Vol. 30, no 2, 267-276 p.Article in journal (Refereed) Published
Abstract [en]

A statistical analysis of water quality data from Lake Vänern spanning three decades has been performed in order to establish an appropriate level of complexity for a water quality model. The analysis consists of paired t-tests for differences in the vertical direction and multiple comparison tests (Tukey's honestly significant difference criterion) for differences in the horizontal direction. The analysis indicates significant differences between the epi- and hypolimnion during stratified periods, but no significant differences in mixed periods. The two distinct basins are only marginally different. Furthermore, each basin can be considered well-mixed horizontally, except for parts located close to point emissions, or the particularly shallow regions.

Place, publisher, year, edition, pages
2004. Vol. 30, no 2, 267-276 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-91682DOI: 10.1016/S0380-1330(04)70344-5OAI: oai:DiVA.org:uu-91682DiVA: diva2:164496
Available from: 2004-05-04 Created: 2004-05-04 Last updated: 2013-03-22Bibliographically approved
In thesis
1. Appropriate Modelling Complexity: An Application to Mass Balance Modelling of Lake Vänern, Sweden
Open this publication in new window or tab >>Appropriate Modelling Complexity: An Application to Mass Balance Modelling of Lake Vänern, Sweden
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This work is about finding an appropriate modelling complexity for a mass-balance model for phosphorus in Lake Vänern, Sweden. A statistical analysis of 30 years of water quality data shows that epilimnion and hypolimnion have different water quality and should be treated separately in a model. Further vertical division is not motivated. Horizontally, the lake should be divided into the two main basins Värmlandssjön and Dalbosjön. Shallow near shore ares, bays and areas close to point sources have to be considered as specific sub-basins if they are to be modelled correctly.

These results leads to the use of a model based on ordinary differential equations. The model applied is named LEEDS (Lake Eutrophication Effect Dose Sensitivity) and considers phosphorus and suspended particles. Several modifications were made for the application of the model to Lake Vänern. The two major ones are a revision of the equations governing the outflow of phosphorus and suspended particle through the outflow river, and the inclusion of chemical oxygen demand (COD) into the model, in order to model emissions from pulp and paper mills. The model has also been modified to handle several sub-basins.

The LEEDS model has been compared to three other eutrophication models applied to Lake Vänern. Two were simple models developed as parts of catchment area models and the third was a lake model with higher resolution than the LEEDS model. The models showed a good fit to calibration and validation data, and were compared in two nutrient emission scenarios and a scenario with increased temperature, corresponding to the green house effect.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 42 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 971
Earth sciences, Lake Vänern, phosphorus, mass balance modelling, model complexity, Geovetenskap
National Category
Earth and Related Environmental Sciences
urn:nbn:se:uu:diva-4239 (URN)91-554-5950-1 (ISBN)
Public defence
2004-05-26, 9C204 (Ericssonsalen), Karlstad University, 11:00
Available from: 2004-05-04 Created: 2004-05-04Bibliographically approved

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