KWI Conduit
Volume VII, Number 1-2
Spring/Fall 1999
Conference Notes

Summary of KWI Symposium on Karst Modeling
24-27 February 1999
Charlottesville, Virginia, USA

Arthur N. Palmer

Groundwater, with its well-established equations for laminar flow and mass balance, lends itself readily to numerical modeling. Karst aquifers are a dramatic exception because of the presence of turbulent flow through solution conduits. Programmers have no difficulty incorporating pipe-flow into numerical models, but if the location of the "pipes" is unknown, as it usually is, there is no hope of devising a predictive flow model in such aquifers. In fact, one begins to question whether numerical modeling can cope with the uncertainties inherent in any bedrock aquifer.

To confront this issue, the KWI held a symposium on Karst Modeling was held in Charlottesville, Va., on February 24-27, 1999.
which featured the leading karst modelers from North America and Europe, together with most American karst field researchers.

During the symposium it became clear that no single modeling technique can adequately characterize karst aquifers, and that we must rely instead on a synthesis of conceptual, analytical, numerical, and statistical techniques. Although numerical models have captured the scientific high ground, it was readily acknowledged that they are unsuited to quantitative prediction of groundwater flow and contaminant dispersion in real karst aquifers. They are instead best used for evaluating idealized conditions, in particular the geomorphic evolution of solution conduits. Such models have gone a long way toward explaining the nature and distribution of karst porosity.

Representatives from several European universities revealed geomorphic models based on recent advances in carbonate dissolution kinetics. EPA software for interpreting quantitative dye traces was demonstrated. The modeling team from the University of Waterloo (Ontario) described their latest software dealing with contaminant dispersion in fractured media. A thought-provoking conclusion from their presentation, demonstrated with a succession of models of increasing refinement, was that discretization errors -- the result of choosing too coarse a finite-element or finite-difference grid -- can produce answers
that are not simply approximate, but entirely wrong.

Any kind of model must be grounded on solid field evidence, a rare commodity in the growing trend toward desktop geology. Thus a powerful first step in karst studies is to develop a valid conceptual model -- one that applies hydrologic and chemical concepts to the local geologic setting. Threaded throughout the symposium were presentations that clearly demonstrated the hazards posed by groundwater studies divorced from the conceptual geologic framework. In case histories, travel times estimated for karst groundwater on the basis of traditional well tests and linear flow equations were shown by dye traces to have
been overestimated by two orders of magnitude.

Even dye tracing, the karst hydrologist's ace-up-the-sleeve, came under close scrutiny. Recent data on dye stability, spectrometry,
multiple dye breakthrough curves, and the nature of background fluorescence have strengthened the scientific basis for tracer studies. But they also confirm that tracer studies can be unreliable in inexperienced hands. The uncertainty of predicting conditions within karst aquifers has encouraged the development of statistical models. Applying fractals and probability to the distribution of karst porosity shows promise for facilitating exploratory and management decisions. Instead of the yes-no answers that clients normally expect from environmental studies, a scientifically valid answer should ideally be stated in terms of probability and confidence levels. Field data are rarely sufficient to provide a statistically valid data base, but this is a desirable and attainable goal.

As programmers become more skilled at simulating the natural world, the distinction between physical and virtual reality becomes
blurred. The greatest challenge is to determine the true nature of what is being modeled. Of any geologic setting, karst poses the most serious problems of water supply, water quality, land stability, and prediction of mineral resources. The difficulties of modeling these phenomena are all too apparent. The convergent nature of the approaches offered by the symposium participants, in spite of their diversity, shows promise for a coherent strategy in addressing these problems in the future.

The Karst Modeling symposium was made possible by grants from the National Science Foundation, the Army Research Office (Corps of Engineers Waterways Experiment Station), the Donors of the Petroleum Research Fund of the American Chemical Society, and the Cave Conservancy of the Virginias. A 265-page symposium volume is available from Elizabeth L. White, email: wbw2@psu.edu.

Special Symposium on Processes of Karst Terrains at the 31st International Geological Congress

Yuan Daoxian and Ivo Karmann have convened a symposium entitled Processes of Karst Terrains (No. 20-6) during the 31st International Geological Congress which will be held 06-17 August 2000 in Rio de Janeiro, Brazil.  An IGCP 379 business meeting will be held during the conference in association with the symposium.  Those interested in participating in the session must submit abstracts before 01 October 1999.  Abstract submissions may be made through the conference's web site (http://www.31igc.org).  More information on the symposium can be obtained by e-mailing Yuan Daoxian (dxyuan@mailbox.gxnu.edu.cn) or Ivo Karmann (ikarmann@spider.usp.br).

1st International Conference on Sustainable Development in Karst Regions
24-27 August 2001
Beijing, China

The Geological Society of China and other scientific communities are planning the 'First International Conference on Sustainable Development in Karst Regions' in August 24-27, 2001, in Beijing, China.  The conference is being hosted by over twenty Chinese scientific organizations concerned with geology, geography, agriculture, environmental issues, etc.  Primary among these organizations are the Chinese Geological Society, the Chinese Geographical Society, the Chinese Geological Hazard Society, and the China International Conference Center for Science and Technology.

Discussions and presentations at the conference will deal with issues germane to the sustainable development of karst regions.  The topics will include:

Before and after the conference, a total of four field trips will be organized to investigate typical karst regions in the Guangxi
Zhuang Autonomous Region, the Guizhou Province, the Sichuan Province, and the Three Gorges of the Yangtze River.  Also included will be visits to related water power stations, thermal springs, some tourist caves, and examples of treatment strategies for some karst geological hazards.

For More information contact:

Mr. WANG wei, Miss. WANG Yanjun
GEOLOGICAL SOCIETY OF CHINA
NO. 26   Baiwanzhuang
Beijing   100037
P. R. China
Telephone: 86-10-68311539
                 86-10-68311133 Ext.2248
Fax: 86-10-68311324
E-mail: CAGSDIC@public.bta.net.cn
 

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Please direct comments and/or suggestions to:
Toby Dogwiler (conduit@karstwaters.org)
Editor KWI Conduit
University of Missouri-Columbia
Department of Geological Sciences
101 Geological Sciences Building
Columbia, Missouri  65211
USA

KWI Conduit
(c) 1999 Karst Waters Institute