1. General Model Information
Name: Enhanced Trickle Down (ETD) Model
Main medium: terrestrial + aquatic
Main subject: biogeochemistry, hydrology
Organization level: ecosystem
Type of model: ordinary differential equations
Keywords: acidification, cation exchange, chemical weathering, sulphate sorption,sulphate reduction, snowmelt, interflow, overland flow, groundwater flow, frozen ground processes, seepage
Dr. Nikolaos P. Nikolaidis
Dept. of Civil Engineering
University of Connecticut
Storrs, CT 06269 USA
Phone: +1 203-486-5648
Fax : +1 203-486-2298
A generalized soft water acidification model has been developed.
The enhanced trickle- down (ETD) model is driven by precipitation, evaporation,
acidity, sulphate, and chloride loading time series daily input data. The hydrologic
component simulates snowmelt, interflow, overland flow, groundwater flow, frozen ground
processes, seepage, and evapotranspiration. Physicochemical and biological processes
that affect the alkalinity or sulphate balance and are included in the formulation are
cation exchange, chemical weathering, sulphate sorption, and sulphate reduction. The
system of 20 ordinary differential equations is solved by using a variable timestep
fourth-order predictor-corrector numerical scheme. Shown here is calibration of the
ETD model for two lakes in the Adirondack Park of New York. ETD is relatively simple
and requires limited input data, and yet it accounts for the predominant hydrologic
and biochemical processes of the ecosystem.
The Enhanced Trickle- Down model can be used to model the
hydrologic and geochemical response of surface water watersheds to freshwater
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
Operating System(s): DOS
Programming Language(s): FORTRAN
III. Mathematical Information
Nikolaidis, N.P., Hu, H., and Ecsedy, C., 1994. Effects of climatic variability on freshwater watershed: case studies. Aquatic Sciences, Vol. 56, No. 2, pp. 161-178.
Nikolaidis, N.P., Hu, H., Ecsedy, C., and Lin, J.D., 1993. Hydrologic response of freshwater watersheds to climatic variability; model development. Water Resources Research, Vol. 29, No. 10, pp. 3317-3328.
Nikolaidis, N.P., Muller, P.K., Schnoor, J.L., and Hu, H.L., 1991. Modelling the hydrogeochemical response of a stream to acid deposition using the enhanced trickle- down model. Research Journal of Water Pollution Control Federation, Vol. 63, No. 3, pp. 220-227.
Georgakakos, K.P., Valle-Folho, G.M., Nikolaidis, N.P., and Schnoor, J.L., 1989. Lake acidification studies: the role of input uncertainty in long-term predictions. Water Resources Research, Vol. 25, No. 7, pp. 1511-1518.
Nikolaidis, N.P., Schnoor, J.L., and Georgakakos, K.P., 1989. Modelling of Long-Term Lake Alkalinity Responses to Acid Deposition. Journal of Water Pollution Control Federation, Vol. 61, No. 2, pp. 188-199.
Nikolaidis, N.P., Rajaram, H., Schnoor, J.L., and Georgakakos, K.P., 1988. Generalized softwater acidification model. Water Resources Research, Vol. 24, No. 12, pp. 1983-1996.
Nikolaidis, N.P., 1987. Modelling the Direct Versus Delayed response of Surface Waters to Acid Deposition in the Northeastern United States. Ph.D. Thesis, Civil and Environmental Engineering, University of Iowa, pp. 288.
Schnoor, J.L., Georgakakos, K.P., Lee, S., Nikolaidis, N.P., and Rajaram, H., 1990. Lakes Resources at Risk to Acidification in the Northeastern Unites States: Diract-Delayed Response Project. Final Report, Cooperative Agreement CR-812329, U.S., EPA, ERL, Corvallis, Oregon.
V. Further information in the World-Wide-Web
VI. Additional remarks
Last review of this document by: T. Gabele: 10. 10. 1998
Status of the document:
last modified by
Tobias Gabele Wed Aug 21 21:44:42 CEST 2002