Hidrogeología del Karst de Pico Frentes (Cordillera Ibérica, España)

El sistema kárstico de Pico Frentes se ha desarrollado a favor de un conjunto calcáreo del Cretácico Superior cuya geometría plegada muy bien definida ha condicionado que los acuíferos se sitúen principalmente en tres sinclinales hidráulicamente conectados, con una capacidad de reservas subterráneas de entre 5 y 7 hm3. La recarga en este acuífero libre y en penillanura es autógena y difusa. El flujo subterráneo va dirigido a gran escala por el fondo de los sinclinales y a pequeña escala mediante corrientes subterráneas hacia los manantiales de Fuentetoba (210 l/s) y nacimiento del rio Mazos (50 l/s), surgiendo en aguas altas otras descargas menores. El análisis de los hidrogramas de estos manantiales indica un sistema de régimen muy variable y poco poder de regulación natural, característica de un acuífero típicamente kárstico, con gran capacidad de renovación y poco tiempo de residencia. Gracias a la simulación de los hidrogramas de estas surgencias mediante un modelo matemático de precipitación –escorrentía, se ha cuantificado de manera detallada el balance hidráulico medio para una serie de 20 años: aportación pluviométrica 16,86 hm3 (100%), recarga natural 8,35 hm3 (49,53%), EVT 8,50 hm3 (50,41%), bombeo de agua subterránea 0,01hm3 (0,06%), escorrentía superficial 0 hm3, transferencias subterráneas a otros acuíferos 0 hm3.

A GIS-based methodology to quantitatively define an Adjacent Protected Area in a shallow karst cavity: The case of Altamira cave

Different types of land use are usually present in the areas adjacent to many shallow karst cavities. Over time, the increasing amount of potentially harmful matter and energy, of mainly anthropic origin or influence, that reaches the interior of a shallow karst cavity can modify the hypogeal ecosystem and increase the risk of damage to the Palaeolithic rock art often preserved within the cavity. This study proposes a new Protected Area status based on the geological processes that control these matter and energy fluxes into the Altamira cave karst system. Analysis of the geological characteristics of the shallow karst system shows that direct and lateral infiltration, internal water circulation, ventilation, gas exchange and transmission of vibrations are the processes that control these matter and energy fluxes into the cave. This study applies a comprehensive methodological approach based on Geographic Information Systems (GIS) to establish the area of influence of each transfer process. The stratigraphic and structural characteristics of the interior of the cave were determined using 3D Laser Scanning topography combined with classical field work, data gathering, cartography and a porosity–permeability analysis of host rock samples. As a result, it was possible to determine the hydrogeological behavior of the cave. In addition, by mapping and modeling the surface parameters it was possible to identify the main features restricting hydrological behavior and hence direct and lateral infiltration into the cave. These surface parameters included the shape of the drainage network and a geomorphological and structural characterization via digital terrain models. Geological and geomorphological maps and models integrated into the GIS environment defined the areas involved in gas exchange and ventilation processes. Likewise, areas that could potentially transmit vibrations directly into the cave were identified. This study shows that it is possible to define a Protected Area by quantifying the area of influence related to each transfer process. The combined maximum area of influence of all the processes will result in the new Protected Area. This area will thus encompass all the processes that account for most of the matter and energy carried into the cave and will fulfill the criteria used to define the Protected Area. This methodology is based on the spatial quantification of processes and entities of geological origin and can therefore be applied to any shallow karst system that requires protection.

Geology, hydrogeology, and water quality of the karst regions of southwestern Illinois and Southeastern Missouri /

"33rd annual meeting, April 1999 North-Central section, Geological Society of America" --cover.

Lattice Boltzmann modeling of fluid flow and solute transport in karst aquifers

A novel modeling approach is applied to karst hydrology. Long-standing problems in karst hydrology and solute transport are addressed using Lattice Boltzmann methods (LBMs). These methods contrast with other modeling approaches that have been applied to karst hydrology. The motivation of this dissertation is to develop new computational models for solving ground water hydraulics and transport problems in karst aquifers, which are widespread around the globe. This research tests the viability of the LBM as a robust alternative numerical technique for solving large-scale hydrological problems. The LB models applied in this research are briefly reviewed and there is a discussion of implementation issues. The dissertation focuses on testing the LB models. The LBM is tested for two different types of inlet boundary conditions for solute transport in finite and effectively semi-infinite domains. The LBM solutions are verified against analytical solutions. Zero-diffusion transport and Taylor dispersion in slits are also simulated and compared against analytical solutions. These results demonstrate the LBM’s flexibility as a solute transport solver. The LBM is applied to simulate solute transport and fluid flow in porous media traversed by larger conduits. A LBM-based macroscopic flow solver (Darcy’s law-based) is linked with an anisotropic dispersion solver. Spatial breakthrough curves in one and two dimensions are fitted against the available analytical solutions. This provides a steady flow model with capabilities routinely found in ground water flow and transport models (e.g., the combination of MODFLOW and MT3D). However the new LBM-based model retains the ability to solve inertial flows that are characteristic of karst aquifer conduits. Transient flows in a confined aquifer are solved using two different LBM approaches. The analogy between Fick’s second law (diffusion equation) and the transient ground water flow equation is used to solve the transient head distribution. An altered-velocity flow solver with source/sink term is applied to simulate a drawdown curve. Hydraulic parameters like transmissivity and storage coefficient are linked with LB parameters. These capabilities complete the LBM’s effective treatment of the types of processes that are simulated by standard ground water models. The LB model is verified against field data for drawdown in a confined aquifer.