1. General Model Information

Name: groundwater flow and nitrate transport model for erosion of

Acronym: FLOW2D


Main medium: terrestrial
Main subject: biogeochemistry, hydrology
Organization level: Ecosystems
Type of model: partial differential equations (finite elements,2D)
Main application:
Keywords: groundwater flow, saturated, nitrate, transport, contaminant, mass balance equation, continuity equation, Darcy's law, continuity equation, rectangular grid, finite difference numerics,

Contact:

Guenter Braun
University of Osnabrueck
Institute of Environmental Systems Research
Artilleriestr 34
49069 Osnabrueck, Germany
Phone: +49-541-9692546
Fax : +49-541-9692599
email: gbraun@ramses.usf.uni-osnabrueck.de

Author(s):

Guenter Braun
Schmidt, JuergenUniversity of Osnabrueck
Institute of Environmental Systems Research

Abstract:

contents of the model
The model simulates transient 2-dimensional ground-water flow in a saturated confinded or unconfined aquifer and nitrate transport via this flow. The modelconsiders both pumping of water and outflow by rivers as well as recharging by ground-water renewal. It was designed as the hydro-geological part of a multi-disciplinary model describing the drainage of nitrate in the district of Vechta in Lower Saxony, Ger-many. The whole model is considering ecological, economical and sociological aspects. Nevertheless, 'flow2d' is a 'stand-alone' ground-water flow model and is therefore transferable to virtually every location (consisting of a soil structure that is sufficiently homogenous).
principles of the model
The model works on a rectangular area with a system of nodes superimposed on it. Each node is representing a smaller subarea of the domain. This is achieved by spatially discretizating the area, which divides it into smaller rectanufis/gles. These rectangles need not be of the same size. Each of them is assumed to be homogenous and both level of the ground water and the concentration of nitrate in the element are calculated for it's central point, thus providing a discrete ground-water level and a discrete nitrate distribution for the domain. Transmission boundary conditions according to Shamir and Harlemann (1967) (concentration gradient to the inside has to equal concentration gradient to the outside) are used on the edges.

Author of Abstract: UFIS - Environmental Research Information System


II. Technical Information

II.1 Executables:

Operating System(s): UNIX RAM required: 8 MB Disc space: > 41 MB; 2 files require each about 20MBytes. There exists a package of the program containing UNIX-shell-scripts and auxiliary programs which generate these files that requires much less space. Portability onto other systems: Portable to any computer system that is able to run FORTRAN 77.

II.2 Source-code:

Programming Language(s): FORTRAN 77; ITPACK 2C, Center for Numerical Analysis, University of Texas, Austin, USA; YSMP, Yale University, New Haven, USA

II.3 Manuals:

Complete model documentation: Arbeitsgruppe Systemforschung: Nitratversickerung im Kreis Vechta: Simulationen und ihr Praxisbezug. Beitraege der Arbeitsgruppe Systemforschung der Universitaet Osnabrueck, Beitrag Nr. 18, Lieth, H. (editor(s)), Universitaet Osnabrueck (1993).

II.4 Data:



III. Mathematical Information


III.1 Mathematics

This is a list of model equations sorted by their characteristics with hypertext links for more details.

III.2 Quantities

This is a list of model quantities sorted by their characteristics with hypertext links for more details.

III.2.1 Input

III.2.2 Output


IV. References

Schmidt, Juergen 1991.Entwicklung und Anwendung eines physikalisch begruendeten Simulationsmodells fuer die Erosion geneigter, landwirtschaftlicher Nutzflaechen.

Josopait, U., 1986.Transmissivity map
Niedersächsisches Landesamt für Bodenforschung; Unterabteilung Hydrologie.



V. Further information in the World-Wide-Web



VI. Additional remarks

Additional information
Last review of this document by: T. GabeleNov 21th 1997
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:42 CEST 2002

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