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Interpretation of pumping tests in a mixed flow karst system
Author(s) -
Maréchal JeanChristophe,
Ladouche Bernard,
Dörfliger Nathalie,
Lachassagne Patrick
Publication year - 2008
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2007wr006288
Subject(s) - electrical conduit , karst , aquifer , hydraulic conductivity , geology , drawdown (hydrology) , superposition principle , matrix (chemical analysis) , geotechnical engineering , hydrology (agriculture) , flow (mathematics) , carbonate rock , hydrogeology , mechanics , soil science , groundwater , materials science , engineering , physics , sedimentary rock , mechanical engineering , paleontology , quantum mechanics , composite material , soil water
A long‐duration pumping test performed in the conduit of a mixed flow karst system (MFKS) is analyzed and interpreted. It constitutes a unique experiment of catchment wide response of a karst system, with drawdowns measured both in the pumped conduit and in the matrix. A modeling approach is proposed for this interpretation. The developed double continuum model consists of two reservoirs ‐ karst conduits and the surrounding carbonate rocks ‐ between which flow exchange is modeled using the superposition principle and the hypothesis of Darcian flow in the matrix considered as an equivalent porous media. The karst conduits are assumed to have an infinite hydraulic conductivity. Model calibration results in a very good match (relative root mean square [rRMS] = 2.3 %) with drawdown measured at the pumping well (karst conduit). It shows that the matrix hydrodynamic parameters (hydraulic conductivity and storativity) have a greater influence on the drawdown than the storage capacity of the conduit network. The accuracy of the model relies mostly on a very good knowledge of both pumping rate and natural discharge at the spring (with and without pumping). This type of approach represents an advance in double continuum modeling of karst systems. It also provides a methodology for the management of water resources from karst aquifers.