Marechal Jean-Christophe

Senior Hydrogeologist

Curriculum vitae




1039 rue de Pinville
34000 Montpellier

Pumping test interpretation in karst aquifers

Diagnostic Plots Applied to Well-Tests in Karst Systems

Jean-Christophe Maréchal, Bernard Ladouche, Benoît Dewandel, Perrine Fleury, Nathalie Dörfliger

Jacques Mudry, François Zwahlen, Catherine Bertrand, James W. LaMoreaux, {H2Karst} {Research} in {Limestone} {Hydrogeology}, Springer International Publishing, Cham, 2014, pp. 127--137

Interpretation of pumping tests in a mixed flow karst system

J C Marechal, B Ladouche, N Dorfliger, P Lachassagne

Water Resources Research, vol. 44, 2008

A well intersecting a karst conduit acting as a vertical fracture of finite length and finite hydraulic conductivity: (a) Linear flow in the conduit or wellbore/conduit storage effect during early pumping times; (b) Bi-linear flow; (c) Matrix linear flow; (d) Matrix pseudo-radial flow during late pump-ing times, modified after (CINCO-LEY & SAMANIEGO-V, 1981); (e) Diagnostic plot of the same case
During early pumping times (Fig. a), conduit linear flow (conduit or wellbore storage effect) is characterized by a straight line with a slope n = 1 on the diagnostic plot. After a transition flow period, the system may or may not exhibit a bi-linear flow period (Fig. b), indicated by a one-fourth-slope straight line that lasts as long as the conduit boundaries do not affect the flow pattern. As time increases, the flow in the matrix becomes one-dimensional (horizontal, parallel and perpendicular to the conduit) as illustrated on Figure c. On a diagnostic plot, the slope of the derivative curve is n = 0.5. As pumping continues, the flow pattern can change from parallel flow to pseudo-radial flow (Fig. d). During this period, the pumped water originates from farther away and the local effect of the finite-length conduit tends to disappear. The drawdown curve tends to the Jacob straight line with a slope n = 0 of the derivative at late times, but this would arise only if the duration of the pumping test is very long. This four-period flow-pattern geometry makes it impossible to interpret such drawdown curves with classical techniques. The corresponding typical drawdown and derivative curves (diagnostic plot) are illustrated on Fig. e.

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