Improving accuracy and efficiency in discrete-continuum karst models

Rooij, Rob de

doi:10.1007/s12665-019-8115-5

Cited by 8 publications

(10 citation statements)

References 23 publications

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“…In Schritt 5 werden für jedes Modell die hydrogeologischen Rahmenbedingungen angewendet und die Strömungsgleichungen für die Gesteinsmatrix, für die Trennflächen und für die Karströhren gelöst [16]. Das Ergebnis ist eine vollständige Verteilung der hydraulischen Druckhöhen und Grundwassergeschwindigkeiten in den Modellen.…”

Section: Topicsunclassified

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Probabilistische Prognose von Karstwasserzutritten beim Bau von Untertagebauwerken

Filipponi

Renard

Dall'Alba

et al. 2022

Geomechanics and Tunnelling

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Various methods have been developed in recent decades to predict hazards associated with karst voids in underground construction. Common to all these methods is that the predicted range of water inflow is often insufficient for the purpose of implementing the planned construction works. This is usually due to an incomplete knowledge of the karst conduit system within a project area, making it difficult to predict the position and characteristics of karst voids. The method presented in this paper permits a robust prediction of karst water inflow. It is based on a combination of stochastically generated, pseudo‐genetic karst conduit systems and hydraulic modelling of the hydrogeological conditions using a Monte Carlo approach. This approach facilitates a plausible estimation of the expected range of karst‐induced water inflows and also enables the probability of encountering a karst voids. to be determined. The predictions allow for differentiated treatment of the hazards associated with karst water during the construction and operation phase of underground structures. In concrete terms, this relates to the planning and implementation of exploratory measures and ground‐improvement measures, the design of the dewatering system and its monitoring during the construction and operation phase.

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Section: Topicsunclassified

“…In Step 5 the hydrogeological framework conditions are applied to each model and the flow equations for the rock matrix, discontinuities and karst conduits are solved [16].…”

Section: Topicsmentioning

confidence: 99%

Probabilistische Prognose von Karstwasserzutritten beim Bau von Untertagebauwerken

Filipponi

Renard

Dall'Alba

et al. 2022

Geomechanics and Tunnelling

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“…However, Dufoyer et al [19] assigned a narrow range of 0.1 to 1.5 (unitless) to the exchange coefficient for simulating a karst aquifer based on the numerical double porosity model called MARTHE. Moreover, De Rooij [39] suggested a well-index in the DisCo model instead of the lumped exchange coefficient that is defined in the MODFLOW-2005 CFPM1 code. The dependence of the well-index on the spatial discretization constitutes the main difference with the lumped exchange coefficient.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

The Effects of Exchange Flow on the Karst Spring Hydrograph under the Different Flow Regimes: A Synthetic Modeling Approach

Shirafkan

Mohammadi

Sivelle

et al. 2021

Water

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In this study, a synthetic modeling approach is proposed to quantify the effect of the amount and direction of the exchange flow on the karstic spring discharge fluctuations under different hydrologic conditions corresponding to high and low flow conditions. We hypothesis that the spring discharge fluctuations constitute a valuable proxy to understand the internal processes of the karst system. An ensemble of spring hydrographs was synthetically produced to highlight the effect of exchange flow by exploring the plausible range of variability of coefficients of exchange flow, conduit diameter, and matrix hydraulic conductivity. Moreover, the change of the rate of point recharge through the karst conduit allows for the quantifying of the sensibility of the spring hydrograph to the directions of exchange flow. We show that increasing the point recharge lies to a remarkable linear recession coefficient (β) as an indication of the conduit flow regime. However, a reduction in and/or lack of the point recharge caused the recession coefficient to change to exponential (α) due to the dominant effect of the matrix restrained flow regime and/or conduit-influenced flow regime. The simulations highlight that the exchange flow process from the conduit to the matrix occurred in a short period and over a restricted part of the conduit flow regime (CFR). Conversely, the exchange flow dumped from the matrix to the conduit occurs as a long-term process. A conceptual model is introduced to compare spring hydrographs’ characteristics (i.e., the peak discharge, the volume of baseflow, and the slope of the recession curve) under the various flow conditions with the directions of the exchange flow between the conduit and the matrix.

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“…Again the advantage is that we can constrain the simulations by statistical data available in the zone of interest. And finally, for the flow simulation we use the recent DisCo code that is capable of handling complex karst networks embedded in a permeable matrix (De Rooij et al, 2013;De Rooij, 2019). The code uses a well-index to describe efficiently the exchanges between the matrix and the conduits, and it accounts both for laminar and turbulent flow.…”

Section: Introductionmentioning

confidence: 99%