1. General Model Information


Acronym: LIMNOD

Main medium: aquatic
Main subject: biogeochemistry, hydrology
Organization level: ecosystem
Type of model: ordinary differential equations, partial differential equations
Main application:
Keywords: water quality, lakes, sediment, phosphorus dynamics, carbon dynamics


Dr. J. Trösch
Lab. of Hydraulics, Hydrology and Glaciology
Eldgenössische Technische Hochschule
CH-8092 Zürich
Fax :
email: trösch@VAW.ethz.ch



LIMNOD is a one-dimensional vertical lake model which considers coupled physical, biochemical and sedimentation processes. For the physical description (state variables are temperature and conductivity), the lake is divided into fully mixed epilimnion and a hypolimnion with a sharp thermocline between these layers. The thermocline depth is calculated daily by means of an energy-balance considering heat and radiation exchange with the atmosphere and energy input by the wind. In the hypolimnon the turbulent mixing processes are expressed by the concept of a time and depth dependent eddy diffusion.
Based on the physical processes a cycle of nutrients is calculated with phosphorus as limiting nutrient (state variables are the concentrations of particular organic carbon (biomass), dissolved oxygen and dissolved and particular phosphorus). In the sediment two types of organic phosphorus, inorganic phosphorus and organic carbon are considered. In this coupled system, transport of chemical species is governed by the physical model. Inversely, biochemical processes influence the stability of the water column due to light extinction by biomass reducing the penetration depth of the incoming short wave radiation and due to dissolution of settling particles from the epilimnion, enhancing the concentration of dissolved species in the hypolimnion.

Model purpose
LIMNOD is a physical-biochemical model for long-term prediction of water quality in lakes. The effects of restoration measures such as oxygenation, deep water drainage and artificial mixing can also be studied. The model is adaptable to most lakes by adjusting some lake specific parameters or by adding new state variables.
Source of the Abstract:
Joergensen S.E., B. Halling-Soerensen and S.N Nielsen (Edts.) 1996: Handbook of Environmental and Ecological Modelling. CRC Press Boca Raton et al. 672 pp.

II. Technical Information

II.1 Executables:

Operating System(s): DOS

II.2 Source-code:

Programming Language(s): FORTRAN 77

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

Karagounis, I., 1992. Ein physikalisch- biochemisches Seemodell; Anwendung auf das Nordbecken des Luganersees. Communications Nr. 116 of the Laboratory of Hydraulics, Hydrology and Glaciology, Federal Institute of Technology, Zürich, Switzerland.

Karagounis, I., Trösch, J., and Zamboni, F., 1993. A coupled physical- biochemical lake model for forecasting water quality. Aquatic Sciences, Vol. 2: pp.87-102.

V. Further information in the World-Wide-Web

VI. Additional remarks

Last review of this document by: T. Gabele: 15. 10. 1998
Status of the document: -
last modified by Tobias Gabele Wed Aug 21 21:44:45 CEST 2002

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