Ground-Water Monitoring in Karst Terranes: Recommended Protocols and Implicit Assumptions


James Quinlan


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Publication Date

March 1989


Reliable monitoring of ground-water quality in any terrane is difficult: There are many ways in which violation of sound principles of monitoring-network design and good sampling protocol make it easy to acquire data that are not representative of the water or pollutants within an aquifer. In karst terranes it is especially likely that irrelevant data, inadvertently misrepresenting aquifer conditions, will be obtained. The special problems of monitoring ground water in most karst terranes can be grouped into four major categories of problems that are rarely as significant in other terranes. These categories 1. 2. 3. are: Where t o monitor for pollutants: At springs, cave streams, and wells shown by tracing to include drainage from a facility to be monitored--rather than at wells to which traces have not been run but which were selected because of convenient downgradient location. Wells on fracture traces and fracture-trace intersections and wells located randomly can be successfully used for monitoring, but only if traced positively from the facility to them. Often, the monitoring can only be done several kilometers away from the facility. Where t o monitor for background water quality: At springs, cave streams, and wells in which the waters are geochemically similar to those to be monitored for pollutants but which are shown by tracing not to include drainage from the facility--rather than at wells selected because of convenient location upgradient from it. This, too, may have to be done several-kilometers away from the facility. When to monitor: Before, during, and after storms ormeltwater events and also at known base-flow conditions-- rather than regularly with weekly, monthly, quarterly, semi-annual, or annual frequency. 4. How to reliably and economically determine the answers to problems 1, 2, and 3: Reliable monitoring of ground water in karst terranes can be done, but it is not cheap or easy. These problems exist because many of the assumptions made for monitoring ground-water flow in granular media are


Ground-Water Quality, Terrane, Karst Terranes

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