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.

Helium in solubility equilibrium with quartz and porefluids in rocks - a new approach in hydrology

Quartz crystals in sandstones at depths of 1200 m–1400 m below the surface appear to reach a solubility equilibrium with the 4He-concentration in the surrounding pore- or groundwater after some time. A rather high 4Heconcentration of 4.5x10E-3 cc STP 4He/cm3 of water measured in a groundwater sample would for instance maintain a He pressure of 0.47 atm in a related volume. This value is equal within analytical error to the pressure deduced from the measured helium content of the quartz and its internal helium-accessible volume. To determine this volume, quartz crystals of 0.1 to 1 mm were separated from sandstones and exposed to a helium gas pressure of 32 atm at a temperature of 290°C for up to 2 months. By crushing, melting or isothermal heating the helium was then extracted from the helium saturated samples. Avolume on the order of 0.1% of the crystal volume is only accessible to helium atoms but not to argon atoms or water molecules. By monitoring the diffusive loss of He from the crystals at 350°C an effective diffusion constant on the order of 10E-9 cm2/s is estimated. Extrapolation to the temperature of 70°C in the sediments at a depth of 1400 m gives a typical time of about 100 000 years to reach equilibrium between helium in porewaters and the internal He-accessible volume of quartz crystals. In a geologic situation with stagnant pore- or groundwaters in sediments it therefore appears to be possible with this new method to deduce a 4He depth profile for porewaters in impermeable rocks based on their mineral record.

Geology, hydrology, and quality of water in the Madera area, San Joaquin Valley, California /

Three folded maps in pocket.

Geology and ground-water hydrology of the Heart River irrigation project and the Dickinson area,

Mode of access: Internet.

Pacific Southwest Inter-Agency Committee : report of the Hydrology Subcommittee : summary of hydrologic criteria for dams.

Mode of access: Internet.

Hydrology of area 56, northern Great Plains and Rocky Mountain coal provinces, Utah /

Mode of access: Internet.

Effects of strip mining the abandoned deep Anna S Mine on the hydrology of Babb Creek, Tioga County, Pennsylvania /

Bibliography: p. 41.

Potential effects of surface coal mining on the hydrology of the Snider Creek area, Rosebud and Ashland coal fields, southeastern Montana /

"February 1983."

Hydrology of the White Tail Butte area, northern Campbell County, Wyoming /

Shipping list no.: 87-323-P.

Potential climatic impacts of increasing atmospheric CO with emphasis on water availability and hydrology in the United States : report prepared for the Environmental Protection Agency /

"April 1984."

Hydrology of area 12, Eastern Coal Province, West Virginia /

Mode of access: Internet.

Hydrology of area 19, Eastern Coal Province, Tennessee /

Mode of access: Internet.

Hydrology of area 24, Eastern Coal Province, Alabama and Georgia /

Mode of access: Internet.

Hydrology of area 5, Eastern Coal Province, Pennsylvania, Maryland, and West Virginia /

Mode of access: Internet.