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[en] Expansive soils can be categorized as one of the geohazards observed in the urban environment, representing a silent hazard to buildings and infrastructure. To evaluate this problematic soil it is necessary to know some of its geotechnical properties. Generally, the average values of soil properties are used in the methods which characterize the geological formation and the lithological group, which causes a great degree of uncertainty. To overcome this problem, this study proposes a procedure for estimating and modelling the principle soil properties that have an impact on expansive soils. The selected case study is located in the Hermanos Cruz neighbourhood in the city of Pinar del Rio in Cuba. The investigation was organized into the following stages: primary assessment of the potential expansiveness of the soils, modelling of the soil properties utilizing 3D geostatistical methods and finally the cartographic representation of the potential Expansiveness of soils on a Geographic Information System (GIS) platform at different depth zones which are of importance in the construction of shallow foundations of engineering works. The application of this methodology in the Hermanos Cruz neighbourhood revealed that its soils possess a potential expansiveness of low to medium, apart from some isolated zones which show a potential expansiveness of medium to high. (Author)
[en] The basin of the El Barreal stream is a dominantly rural area in which groundwater is used for all activities whereas the stream is used as sink of residues and effluents. The existence of a tannery, which discharge the effluents into a wetland (which is drained by the stream), reveals the need to study the presence of Chromium in surface and groundwater and to compare values derived from pollution with those corresponding to the natural water baseline values. Fifty three samples of surface and groundwater were abstracted and chemical analyses were made, including total Chromium in water and plants. The chemical analysis results were studied by means of conventional and statistical techniques. The local and regional geological characteristics allow us to interpret that Chromium in water is derived from source minerals, being possible to stand out that high values probably are related to nearby serpentinite bodies.The values of total chrome in surface and groundwater are included in the natural quality baseline range calculated for this basin (0,25-5ug/L), exempting those samples with higher values linked to sites with farming activities and to the wetland environment where the Chromium effluent is discharged. In the last place, Chromium was retained in soil and plants whereas the aquifer was affected by a contaminant plume of total dissolved solids because of advective-dispersive transport. In the 2009 monitoring survey, a small increase of Chromium in groundwater was detected in relation to that of 2005, being assumed that partial desorption of Chromium is taking place from the solid phase. (Author) 19 refs.
[en] The aim of this paper is to describe the application of an ontology, or up-to-date computerized tool, developed in the field of artificial intelligence and in particular of knowledge engineering, to inert elements, in this case the silicate class, which are minerals of scientific, technical and economic interest. The importance of applying ontology to minerals lies in the fact that these substances are capable of causing negative environmental impacts upon other variables in the natural environment, such as the atmosphere and the hydrosphere, and possible subsequent effects on human health. (Author) 37 refs.
[en] The terms used to identify minerals in public exhibitions usually depends primarily upon the textural, chemical and/or structural problems related to their classification. Furthermore, the label attached to any specimen can only contain a limited amount of information, thus limiting still more the specimen's complete identification. We have examined this problem with the intention of achieving greater rigour in mineral classification whilst at the same time providing the public with the most complete information possible. Five recurring problems encountered in the permanent collections of the Spanish Museum of Geomining in Madrid have been dealt with (allowing the reader to become a virtual visitor): a) specimens made up of several species; b) specimens composed of minerals that form solid-solutions; c) mixed materials of low crystallinity; d) specimens with chemical or structural zones; and e) specimens showing evidence of pseudomorphosis. The minerals involved are common and come from sites in Spain of interest to museums, collectors or commercial ventures. We have only undertaken analyses, using X-ray diffraction, when the information available is non-existent or insufficient. The suggestions made and decisions adopted may help in the labelling of other collections both public and private. (Author) 60 refs.
[en] This paper focuses on the hydrogeological and hydrochemical knowledge of the Nador Plio-Quaternary aquifer in Tipaza, situated along the Algerian coastline. It includes the identification of the hydrodynamic aquifer, hydrogeological and piezometric characteristics and, finally, an overview of the hydro-geochemistry of the area. We carried out this study between 2008 and 2013, with piezometric and hydrochemical monitoring of 24 wells in the study area. The physicochemical analysis of water shows that 25 % of the wells in the coastal zone have values of electrical conductivity greater than 3000 μS/cm The Mg2+/Ca2+ ratio is also higher than one and there are sodium chloride facies due to the mix of freshwater with seawater exceeding 10 % in some places. However, the comparison of the salinity of the groundwater during the period 2008-2013 with 1988-2004 indicates that there is a low dilution due to the reduction of pumping in the aquifer after the construction of the Boukourdane dam. There has also been a more rainy period and a possible return flow from irrigation in the area. (Author)
[en] Managed aquifer recharge (MAR) has been practiced in California for over a century, using a range of artificial recharge methods, including surface spreading basins, injection wells and aquifer storage and recovery (ASR) wells. Intense municipal and industrial development of coastal regions, particularly in southern California, during and following World War II, led to overdraft of coastal groundwater basins, where groundwater levels were drawn down below sea level, resulting in seawater intrusion into freshwater aquifers. Surface water is imported from the Colorado River and later northern California to satisfy water demands of a growing population. This imported water is also a water supply used for injection into to injection wells constructed in the 1960s along the coastline to repel seawater from intruding into coastal aquifers. Since the 1960s, these seawater intrusion barriers have evolved in terms of water supplied for injection and in their construction and operation details. Imported water supplies are being completely replaced with highly treated wastewater and the injection wells are being constructed so that they are more automated to reduce operational costs. The West Coast Basin of southern California is provided as a case study of the evolution of hydraulic barriers used for protection against seawater intrusion into coastal aquifers. (Author)
[en] This paper shows a study on the viability of an artificial recharge in the flood-plain aquifer of the Guadalquivir River (Andalucia, Spain). The method used to the evaluation of the artificial recharge project is as follows: A simple model (one cell). The code has been made on the use of an EXCEL spreadsheet. A distributed parameters-flow model using a standard code (Modflow). A pilot recharge plant. The simple model has been applied in different zones. The model has only 5 parameters. It evaluates the artificial recharge by means of the depletion coefficient. The model was calibrated for a monthly time-step, although the water balances in the soil and in the aquifer were calculated daily. The calibration the distributed parameter-flow model shows a high transmissivity, storage coefficient and porosity. The pilot recharge plant is a trench with recharge wells within it. The water available for recharge is obtained from an irrigation canal. A network of control points has been established to monitor the piezometric levels. The results obtained show a high storage coefficient and porosity. These parameters show a rapid groundwater velocity. Finally, the paper compares and contrasts the results obtained with the simple model, distributed parameter- flow model and the pilot recharge plant. The results are quite similar. The groundwater velocity is rapid. Water remains in the aquifer for a few days before returning to the river. (Author)
[en] We propose a way of defining safeguard zones for groundwater protection according to the requirements of the Water Framework Directive (WFD). Taking into account the peculiarities of the groundwater bodies in the region of the Mediterranean arch, we chose to conduct our study in the Guadalquivir basin in southern Spain, an area of special interest because it combines the influence of rain fronts and the mixed characteristics of both Mediterranean and Atlantic climates, together with the fact that a large percentage of water for human consumption is provided by groundwater, especially at the head of the basin, where this percentage may account for up to 80%. Safeguard zones are defined by an initial delimitation of quality-protection perimeters using the Reduced DRASTIC and COP methods, designed specifically for detrital and karstic aquifers respectively, to assess the potential impact of the existing pressures upon them and study their intrinsic vulnerability. An analysis of all this spatial information using a geographical information system allowed us to test and validate the method used and to obtain an initial definition of safeguard zones in the basin in question. (Author) 37 refs.
[en] The Las Termas uranium-ore deposit, located in the geological province of Sierras Pampeanas, Argentina, is contained within the Precambrian metamorphic basement close to the contact with the Los Ratones Carboniferous granite. This deposit was originally linked to greisenization associated with Carboniferous magmatic activity. Nevertheless, recent data concerning pitchblende-type uraninite (113.6 Ma and 51.4 Ma) and the spatial relationship between the mineralization and Cretaceous rifting volcanism lead us to suggest a new genetic model, developed in two stages. During the first stage Carboniferous greisenization included the leaching of uranium from granite, whilst during the second stage Cretaceous rift-magmatism led to a hydrothermal system, which would have been responsible for uranium mineralization. (Author)
[en] It is performed the first geotechnical synthesis for La Arganosa Formation, the Cretaceous lithostratigraphic unit with very low geomechanical quality under the urban core of Oviedo; it also configures a major regional aquifer. In this study, geotechnical parameters of identification and condition, as well as physical and hydraulic ones, are compiled, statistically treated and interpreted. They were obtained from about 400 laboratory tests and more than 250 field tests around the city. The unit, of detrital origin, is bounded at the bottom and top by limestone lithologies, and is made up of soils and very soft rocks in alternating granular and cohesive layers. It discusses the main properties that define its geotechnical behavior: particle size distribution, plasticity, strength, compactness, consistency, compressibility, expansivity, collapsibility, permeability, and chemical aggressiveness of the materials and water. Furthermore, same numerical values are provided for reference forward guidance for future research to develop on this formation. (Author) 31 refs.