1. General Model Information

Name: Critical loads model of the CCE

Acronym: CL_CCE

Main medium: terrestrial
Main subject: biogeochemistry
Organization level: Ecosystems
Type of model: static-algebraic equations
Main application: decision support/expert system, research
Keywords: critical load, critical levels, soil acidification, proton deposition, nitrogen deposition, sulphur, forest soils,surface waters, spatially distributed


National Institute of Public Health and Environmental Protection, Coordination Center for Effects

Downing, Robert J.
Antonie van Leeuwenhoeklaan 9
3720 BA Bilthoven P.O.Box 1, The Netherlands
Fax :


Downing, Robert J.


contents of the model
The model calculates critical loads of acidity and sulphur. It sumarizes the work of the RIVM Coordination Center for Effects (CCE) and a number of National Focal Centers (NFC). A critical load has been defined as "the highestdeposition of a compound that will not cause chemical changes leading to long-term harmful effects on ecosystem structure and function" (Nilsson 1986). This documentation reflects the 1993 model status described byDowning et al. (1993). Earlier methodologies are not included.
principles of the model
The following ecosystems are considered: Countries submitting national data calculated critical loads for either forest soils, surface waters, or a combination of the two. For countries not submitting national data, critical loads for forest soils were computed, using European data bases which are described by Downing et al. (1993). All maps show the 5-percentile critical load, i. e. the deposition level needed to protect most sensitive 95 % of ecosystem area in each grid cell. (As a basis of the computation of the 5-percentile the actual ecosystem area rather than the total area of the grid cell is used (Downing et al. 1993, p. 21). Three equations especially deal with critical loads for aquatic ecosystems.

II. Technical Information

II.1 Executables:

Operating System(s): Peripherical software required: dBase for using European background data if no national data were submitted List of files: FOREST.DBF critical-loads related data on forests SOIL.DBF critical-loads related data on soils

II.2 Source-code:

Programming Language(s):

II.3 Manuals:

Complete model documentation: Downing, R.J., Hettelingh, J.-P., de Smet, P.A.M. (eds): Calculation and mapping of critical loads in Europe: Status report 1993, RIVM Report, 259101003, Downing, R.J., Hettelingh, J.-P., de Smet, P.A.M. (editor(s)) (1993). ISBN 90-6960-047-1.

II.4 Data:

dBase files available (European 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

Baker, L.A., Brezonik, P.L., 1988. Dynamic model of in-lake alkalinity generation. Water Resources Research 24: 65-74.

Brakke, D.F., Henriksen, A., Norton, S.A., 1990. A variable F-factor to explain changes in base cation concentrations as a function of strong acid deposition. Verh. Internat. Verein. Limnol. 24: 146-149.

de Vries, W., Posch, M., Reinds, G.J., Kamari, J., 1992. Critical loads and their exceedance on forest soils in Europe. Report 58, Winand Staring Center, Wageningen, The Netherlands.

Dillon, P.J., Molot, L.A., 1990. The role of ammonium and nitrate in the acidification of lakes and forested catchments. Biogeochemistry 11: 23-43.

Downing, R.J., Hettelingh, J.-P., de Smet, P.A.M. (eds). 1993. Calculation and mapping of critical loads in Europe: Status report 1993.
RIVM Report 259101003 (1993), ISBN 90-6960-047-1

Henriksen, A., Forsius, M., Kamari, J., Posch, M., Wilander, A., 1993. Exceedance of critical loads for lakes in Finland, Norway and Sweden: Reduction requirements for nitrogen and sulfur deposition. Acid Rain Research Report 32/1993, Norwegian Institute for Water Research, Oslo. pp. 1-43

Lien, L., Raddum, G.G., Fjellheim, A., 1992. Critical loads of acidity to freshwaters - fish and invertebrates. NIVA Rept. 0-89185.

V. Further information in the World-Wide-Web

VI. Additional remarks

The coupling of the CL_CCE - model with the weathering model PROFILE is realized.

Additional information
Last review of this document by: R. Patzak : 1. October 1997 -
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:40 CEST 2002

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