Modeling complex flow in a karst aquifer

Integrating field and numerical modeling methods for applied urban karst hydrogeology

“…6): (1) the northern and southern boundaries were defined as specified head, corresponding to available groundwater head measurements of the regional flow regime; (2) the eastern boundary was defined as specified flow from the adjacent catchment; (3) the western boundary was chosen as a no-flow boundary, according to the abundance of comparatively impermeable geological sequences (see above); and (4) the Birs River was simulated as General Head Boundary (GHB), where river infiltration and groundwater exfiltration are calculated in relation to the difference between river level and hydraulic groundwater head, as well as a conductance of the river bed. Modeling the complex flow using a finite-difference approach, with drain networks, representing the conduit component of model outflow, was achieved by using generalized drain features (Quinn et al, 2006). Two drains were introduced in model layer 4 corresponding to information obtained from (a) boreholes, indicating that voids were generally encountered at the bottom of the weathering zone; (b) the 1996 dye tracer test and (c) the location of fracture joints (Figs.…”

“…Kovacs, 2003). Klimchouk et al (2000) discussed the evolution of karst aquifers and Quinn et al (2006) summarized the existing modeling approaches for simulating flow in karst environments. In the appendix these include: (1) models using equivalent porous medium in which flow is governed by Darcy's law (Anderson and Woessner, 1992); (2) models in which the preferred flow paths are simulated with a very high hydraulic conductivity relative to the surrounding matrix material (double porosity); (e.g.…”

“…This allowed the estimated parameters to be cross-checked and the results from both approaches to be evaluated continuously and interpreted separately. The 3-D hydrogeological model (3-D HGM) presented in this paper includes a deterministic finite difference approach which takes into account an equivalent porous medium for weathered and non-weathered rock, and a coupling of the system with drains that represent a generalization of the conduit component of model outflow (mixed flow in karst settings; Quinn and Tomasko, 2000;Quinn et al, 2006). The calibrated 3-D HGM provided the geometric and hydraulic boundary conditions (modeling domain, groundwater and head of the river, hydraulic conductivity and conductance of the river bed) for the 2-D KEM.…”

Saltwater intrusion estimation in a karstified coastal system using density-dependent modelling and comparison with the sharp-interface approach

“…Some researchers have developed numerical models of coastal karstified aquifers combining two of the aforementioned methods: the equivalent porous medium and the discrete fracture approach (Clemens et al 1996, Kiraly 1998, Graf and Therrien 2005, Quinn et al 2006, Papadopoulou et al 2010b.…”

Lattice Boltzmann Modeling of Fluid Flow and Solute Transport in Karst Aquifers

“…In MODFLOW a continuous branching network of drain cells with drain elevation and conductance is used as an analogue to a karst conduit. The drain cell feature is available in MODFLOW to simulate agricultural drains that remove water from an aquifer at a rate proportional to the difference in water level and some fixed drain elevation (Quinn and Tomasko, 2000;Quinn et al, 2006). Sun and Painter (2004) QTRACER is a computer program developed to analyse breakthrough curve data obtained from tracer studies in karst and fractured-rock aquifers (Field, 1999 …”