Author(s): U. Mohrlok; M. Sauter
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Abstract: The hydraulic properties of karst aquifers can be approximated assuming (a) a lower permeability fissured system with a high storage capacity which is drained by (b) a high permeability but low storativity conduit network. This simplified dualistic view of a karst system can be supported through observations of well and spring hydrograph behaviour, which frequently exhibit two major response frequencies to recharge input: a fast event response and a slow seasonal variation. This behaviour is directly linked with the water storage processes after recharge events and affected by the exchange flux between the fissured system and the draining conduit network. Field observations show that the maximum groundwater level is read several weeks after maximum spring discharge. This feature implies the presence of an intermediate storage which can be either located in the epikarst or the fissured system of the aquifer itself. The epikarst storage model assumes that the bulk of the recharge water is slowly released from the epikarst, while the aquifer storage model asumes that the bulk of recharge is conveyed via vertical shafts to the phreatic zone, where due to the difference in hydraulic gradient water flows from the conduit into the fissured system. In order to test the applicability of either model, the heat transport processes has been investigated. These investigations lead to a better understanding of the recharge and the linked storage processes in karst aquifers.
Year: 1999