How to control the morphology of simulated karst networks?

Augustin Gouy and Pauline Collon and Vincent Bailly-Comte and Christophe Antoine and Philippe Landrein. ( 2023 )
in: 2023 {RING} meeting, pages 24, ASGA

Abstract

In karst aquifers, groundwater flow is highly influenced by the interconnected underground cavities and conduits that form the karst network. Physically-based modeling of karst flows requires the use of spatially distributed approaches accounting for these networks. Their exploration is, however, often complex, and mapping them using indirect methods such as geophysical ones has proven challenging due the highly variable conduit size. To overcome these limitations, stochastically simulating discrete karst networks should allow to account for the uncertainties on conduit position and geometry. Among the existing methods proposed in the literature, only a few can reproduce realistic and diverse karst morphologies. In this work, we propose a new algorithm, KarstNSim, for simulating discrete karst networks, which incorporates field data to generate a range of possible karst network geometries. It solves a shortest path problem between sinks and springs – respectively the inlets and outlets of the network – with the use of an anisotropic cost function defined on an unstructured mesh conformal to geological and structural heterogeneity. This cost function represents the physico-chemical processes that govern speleogenesis – such as erosion and chemical weathering – providing simplified control over the geometry of the generated networks. Our approach reproduces the vadose-phreatic partition visible in the karst networks, by generating sub-vertical conduits in the unsaturated zone and sub-horizontal ones in the saturated part. It encompasses geological parameters such as inception surfaces, fractures, permeability, and solubility of layers, along with considering the hydrological context of recharge by assigning relative weights to the inlets. To evaluate our approach, we simulate various synthetic models to demonstrate the influence of different input parameters on the spatial organization of the past and present karst flows. We also apply KarstNSim to a real case study : the Ribeaucourt (Meuse, France).

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BibTeX Reference

@inproceedings{gouy_how_RM2023,
 abstract = {In karst aquifers, groundwater flow is highly influenced by the interconnected underground cavities and conduits that form the karst network. Physically-based modeling of karst flows requires the use of spatially distributed approaches accounting for these networks. Their exploration is, however, often complex, and mapping them using indirect methods such as geophysical ones has proven challenging due the highly variable conduit size. To overcome these limitations, stochastically simulating discrete karst networks should allow to account for the uncertainties on conduit position and geometry. Among the existing methods proposed in the literature, only a few can reproduce realistic and diverse karst morphologies. In this work, we propose a new algorithm, KarstNSim, for simulating discrete karst networks, which incorporates field data to generate a range of possible karst network geometries. It solves a shortest path problem between sinks and springs – respectively the inlets and outlets of the network – with the use of an anisotropic cost function defined on an unstructured mesh conformal to geological and structural heterogeneity. This cost function represents the physico-chemical processes that govern speleogenesis – such as erosion and chemical weathering – providing simplified control over the geometry of the generated networks. Our approach reproduces the vadose-phreatic partition visible in the karst networks, by generating sub-vertical conduits in the unsaturated zone and sub-horizontal ones in the saturated part. It encompasses geological parameters such as inception surfaces, fractures, permeability, and solubility of layers, along with considering the hydrological context of recharge by assigning relative weights to the inlets. To evaluate our approach, we simulate various synthetic models to demonstrate the influence of different input parameters on the spatial organization of the past and present karst flows. We also apply KarstNSim to a real case study : the Ribeaucourt (Meuse, France).},
 author = {Gouy, Augustin and Collon, Pauline and Bailly-Comte, Vincent and Antoine, Christophe and Landrein, Philippe},
 booktitle = {2023 {RING} meeting},
 language = {en},
 pages = {24},
 publisher = {ASGA},
 title = {How to control the morphology of simulated karst networks?},
 year = {2023}
}