Francisco Carrasco

Advances in Research in Karst Media

The right to water use does not imply total sovereignty by some to the detriment of others over one of the most basic natural resources necessary to sustain life. Both developed and developing countries must find a workable balance for managing water resources. Water use decisions like those affecting Figeh Spring, Damascus, Syria, and Kharga Oases, Egypt, are controlled both by natural parameters, as well as human factors such as land use and population growth. Sustainable Water Development (SWD) is an internationally accepted program for balancing water use issues and goals among competing consumers.

Carbon dioxide concentration in air within the Nerja Cave (Malaga, Andalusia, Spain)

INTRODUCTION In caves adapted for tourism, the control of carbon dioxide levels is crucial for the cave’s conservation as well as for public health, so that an adequate air quality is maintained for the visitors. On one hand, the CO2 concentration in the air in karstic caves conditions the development of different speleogenetic processes within these caves given that it directly influences the precipitation/dissolution of carbonates (White, 1988, 1997; Dreybrodt, 2000; Dreybodt & Eisenlohr, 2000). On the other hand, the CO2 concentration determines the cave’s air quality, as elevated CO2 concentrations above 5000 ppmv are noxious to human health (Halbert, 1982). Numerous authors have studied CO2 from diverse standpoints. Pioneering studies have been made on the presence and dynamics of CO2 in caves with respect to the exterior environment, for example Renault (1968), Ek (1968, 1979, 1981), James (1977) and Troester & White (1984). Other authors

Application of geochemistry and radioactivity in the hydrogeological investigation of carbonate aquifers (Sierras Blanca and Mijas, southern Spain)

The chemical characteristics, 3 H contents and radioactivity of groundwaters from the Sierras Blanca and Mijas (Southern Spain) have been studied in relation to the chemical composition and radioactivity of the aquifer host rocks, and the residence time of the water. The Sierras Blanca and Mijas are made up of calcitic and dolomitic marbles of Triassic age. The groundwaters that drain the calcitic marbles (which outcrop principally in the western Sierra Blanca) have less mineralization, which descreases quickly with recharge (as does the 3 H content), and the gross alpha and beta activities are below detection limit. This is due to the short residence time of water inside the aquifers which are conduit flow systems. The waters of the dolomitic marbles (eastern Sierra Blanca and Sierra Mijas) have higher and less variable mineralization and contain greater concentrations of Mg 2+ , SiO2 and SO 2ˇ 4 (ions normally associated with slow flows). The 3 H contents are more uniform with time (indicating an older age) and there is detectable natural radioactivity, because the waters have a longer residence time in the aquifers, which

DRISTPI, a new groundwater vulnerability mapping method for use in karstic and non-karstic aquifers

This paper proposes a new method, called DRISTPI, to evaluate the intrinsic vulnerability to contamination of different types of aquifers. Taking the DRASTIC method as a starting point, we highlight the need to define two scenarios to differentiate karst materials from the rest of the study area. The changes made in DRISTPI, with respect to DRASTIC, include the elimination of factors that are mainly related to the movement of water through the saturated zone of the aquifer (the original A and C factors) because the aim of this new method is to protect the groundwater (the resource) rather than the water supply (the source). Furthermore, the DRISTPI method incorporates a new factor called PI to characterize areas of preferential infiltration. Specifically, the vulnerability of two European aquifers with different geological, hydrogeological and climatic characteristics was evaluated using the DRISTPI method, and the results were compared with those obtained using DRASTIC, PI, COP, the Slovene Approach and PaPRIKa methods. These results were statistically analysed by confronting spatial autocorrelation coefficients to measure the cross-correlation between pairs of vulnerability maps.

Hydrogeological and Environmental Investigations in Karst Systems

This paper presents preliminary results from two karst systems belonging to the ‘‘Jurassic Karst’’ observatory in the French Jura Mountains. The sites are characterized by localized and diffuse recharge. Physicochemical monitoring was performed at the karst outlet (springs), as well as in the unsaturated zone (cave and epikarstic spring). During two contrasting flood events, water level, temperature, electrical conductivity, dissolved organic carbon, turbidity, and dissolved oxygen were recorded at high frequency and compared. These preliminary results allow to propose a conceptual model for both sites. It was possible to distinguish specific autogenic and allogenic recharge mechanisms and to characterize the respective contribution of the saturated and unsaturated zones.

Isotopic (13C) Signature of CO2 Sources in the Vadose Zone of a Mediterranean Karst (Nerja Cave Site, Southern Spain)

This study is based on in situ measurements of the soil and the vadose zone (<60 m) in a Mediterranean karst experimental site near Nerja Cave (a show cave in dolomite marbles in South Spain). CO2 concentrations in depth were registered in boreholes drilled in experimental site. The CO2 content generally increases with depth. Measurements indicate average vadose air CO2 concentrations of nearly 40,000 ppm, with a maximum of nearly 60,000 ppm. In this context, the cave itself appears to be a vadose subsystem above the groundwater level, with significantly lower CO2 concentrations (a few thousands of ppm maximum) due to its ventilation. The δ13C–CO2 data of the vadose air point to an origin of the gas mainly related to microbiological processes associated to the consumption of dissolved organic matter in the groundwater surface. This gas can diffuse or flow laterally, upward or downward through karst conduits. Interactions between air masses of surface origin (relatively dry, with variable temperature and low CO2 content) and typical vadose attributes (relatively high CO2 content, near-saturated humidity and 21 °C temperature) produce clear ascendant or descendant air fluxes inside the boreholes, especially those that cross significant karst voids.

Hypothesis on the hydrogeological context of wetland areas and springs related to evaporitic karst aquifers (Málaga, Córdoba and Jaén provinces, Southern Spain)

The northern sector of the External Zone of the Betic Cordillera (S Spain) is formed by an olistostrome unit known as the Chaotic Subbetic Complexes (CSC). This megabreccia is basically made of clays and evaporite rocks (gypsum and salt) of Upper Triassic (Keuper) age as well as other lithologies (dolostones, limestones, marls and calcareous sandstones) belonging to different ages (Jurassic, Cretaceous and Tertiary). Despite of low permeability has been traditionally assumed for these materials, water flow and storage through them is possible due to the aquitard behavior of clays and sandstones and the presence of conduits generated by dissolution/karstification processes within the evaporite rocks. The lithological complexity of the CSC determines its hydrogeological heterogeneity, with groundwater flows of different length and various scales from recharge areas to discharge zones. Thus, wetlands and springs placed at lower altitudes are associated with large (regional) groundwater flows, of greater residence time within the aquifer, and they normally drain high salinity waters mostly connected with ascending flow. This work provides an overview of the main geological and hydrogeological aspects related to groundwater flow within the CSC on the basis of several case-studies. Conceptual models are proposed for these cases, since they are the base to carry out a genetic-functional classification of wetlands potentially useful for their management.

Activities permitted cartography: the integration of groundwater protection into land-use planning

Groundwater is an essential resource as a source of water supply. For this reason, it is necessary to integrate and harmonise efforts to protect groundwater quality with socioeconomic activities and existing land-use patterns in any given region, as well as complying with the requirements of the EU Water Framework Directive. In addition, land management seeks to coordinate and harmonise policies with regional impacts. Water—as a public good and an essential resource for the development of life and the evolution of populations—needs to become one of the main pillars of the management of a variety of regional policies. Therefore, water resources planning does not make sense without first considering forecasted land management patterns. The objective of this study was to enhance a method used to define safeguard zones protecting groundwater bodies intended for human consumption (i.e. the groundwater protection zones method) by developing a cartography method to create a map showing permitted activities in a particular region. This provides an effective tool to assist in the management of regional land use. Delimited safeguard zones that protect groundwater intended for human consumption must be integrated into land-use planning. The proposed development of a map of permitted activities facilitates is to make recommendations and formulate restrictions and prohibitions to avoid damage to groundwater used for human consumption.

The Protection of Groundwaters Destined for Human Consumption in Karstic Aquifers. Advances Towards Safeguard Zones

Carbonate aquifers constitute a water reserve of critical importance as a source of drinking water. For this, it is necessary to establish suitable protection measures so that groundwater bodies can achieve good status as required by the Water Framework Directive (WFD). As a general protection measure, the first advances in the development of a methodology to delimit safeguard zones are presented here. Carbonate aquifers in the south of Spain have been selected as pilot zone for the application of the three phases or stages of work proposed. Initial results obtained, following the application of the selected criteria (vulnerability, pressures, recharge and hydrogeological characteristics) show that the advance in the successive phases allows the necessary protection areas for these types of aquifers to be delimited.

Role of an extension of pre-Quaternary age for the evolution of the carbonate massifs in the occidental Betic Cordillera: The case of the Yunquera-Nieves massif (southern Spain)

A simultaneous analysis of the fracture geometry and paleo-stress fields of the karstic Yunquera-Nieves massif i n southern Spain (Malaga Province) has been carried out with microtectonic stations. It reveals polyphased t ec -tonics linked to the structural position of this carbonate domain in the western Betic Cordillera. Among the tectonic regimes described in this domain appears a distensive stage with a radial trend probably of post-Tortonian to Quaternary age. Todate, it has seldom been described and is absent from geodynamic models though it seems to have had a regional importance. Furthermore, it played a major role for the acquisition of the hydrodynamic properties of t he aquifer and its karstogenesis. This stage opened all fractures and allowed t he development of karstic drains with NW-SE and N-S directions. Finally, the karstic network was shaped by more recent climatic and tectonic events.