Representation of water abstraction from a karst conduit with numerical discrete-continuum models - BRGM - Bureau de recherches géologiques et minières Access content directly
Journal Articles Hydrology and Earth System Sciences Year : 2014

Representation of water abstraction from a karst conduit with numerical discrete-continuum models

Abstract

Karst aquifers are characterized by highly conductive conduit flow paths embedded in a less conductive fissured and fractured matrix, resulting in strong permeability contrasts with structured heterogeneity and anisotropy. Groundwater storage occurs predominantly in the fissured matrix. Hence, most mathematical karst models assume quasi-steady-state flow in conduits neglecting conduit-associated drainable storage (CADS). The concept of CADS considers storage volumes, where karst water is not part of the active flow system but hydraulically connected to conduits (for example karstic voids and large fractures). The disregard of conduit storage can be inappropriate when direct water abstraction from karst conduits occurs, e. g., large-scale pumping. In such cases, CADS may be relevant. Furthermore, the typical fixed-head boundary condition at the karst outlet can be inadequate for water abstraction scenarios because unhampered water inflow is possible. The objective of this work is to analyze the significance of CADS and flow-limited boundary conditions on the hydraulic behavior of karst aquifers in water abstraction scenarios. To this end, the numerical discrete-continuum model MODFLOW-2005 Conduit Flow Process Mode 1 (CFPM1) is enhanced to account for CADS. Additionally, a fixed-head limited-flow (FHLQ) boundary condition is added that limits inflow from constant head boundaries to a user-defined threshold. The effects and the proper functioning of these modifications are demonstrated by simplified model studies. Both enhancements, CADS and FHLQ boundary, are shown to be useful for water abstraction scenarios within karst aquifers. An idealized representation of a large-scale pumping test in a karst conduit is used to demonstrate that the enhanced CFPM1 is able to adequately represent water abstraction processes in both the conduits and the matrix of real karst systems, as illustrated by its application to the Cent Fonts karst system.

Domains

Earth Sciences
Fichier principal
Vignette du fichier
hess-18-227-2014.pdf (3.92 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

hal-01176557 , version 1 (15-07-2015)

Identifiers

Cite

T. Reimann, Markus Giese, T. Geyer, R. Liedl, Jean-Christophe Maréchal, et al.. Representation of water abstraction from a karst conduit with numerical discrete-continuum models. Hydrology and Earth System Sciences, 2014, 18 (1), pp.227-241. ⟨10.5194/hess-18-227-2014⟩. ⟨hal-01176557⟩

Collections

BRGM
311 View
296 Download

Altmetric

Share

Gmail Facebook X LinkedIn More