Joint simulation of multiple variables with a Markov-type coregionalization model

Many applications are multivariate in character and call for stochastic images of the joint spatial variability of multiple variables conditioned by a prior model of covariances and cross- covariances. This paper presents an algorithm to perform cosimulation of such spatially intercorrelated variables. This new algorithm builds on a Markov-type hypothesis whereby collocated information screens further away data of the same type, allowing cosimulation without the burden of a full cokriging. The proposed algorithm is checked against a synthetic multi-Gaussian reference dataset, then against a multi-Gaussian cosimulation approach using full cokriging. The results indicate that the proposed algorithm perform as well as the full cokriging approach in reproducing the univariate and bivariate statistics of the reference set, yet at less cpu cost.     

Evidence of progressive deformation in minor structures in Western Asturias (N. W. Spain)

Examples of progressive deformation provided by minor structures are not frequent in the geological literature. In NW Spain some minor structures in Lower Paleozoic inhomogeneous layered material may be interpreted as the result of progressive deformation during the Hercynian Orogeny. The examples described include structures generated by progressive contraction (folded wedges), contraction followed by elongation (folds disrupted by boudinage) and elongation followed by contraction (folded boudins).     

Sodium-rich dachiardite from Alpe di Siusi,Italy

Dachiardite (a zeolite) occurs as aggregates of thin, parallel fibers in the basalt of Alpe di Siusi, Bolzano, Italy. It is strongly sodic while dachiardite from Elba is mainly calcic. Indexed X-ray diffraction data, unit cell dimensions, chemical formula, density and optical properties are reported.     

Correlation of precipitable water vapour values over the United States with physical and chemical parameters Part II: Seasonal trends with physical variables

Summary Reitan's data on precipitable water vapour over about 45 stations of the U.S.W.B. network are correlated with altitude and average station temperature values. Computations are carried out following a simple proposed model which is found to be obeyed with reasonably good approximation on average monthly and seasonal scales.Contribution of the Centro-Nucleazione Aerosoli of the National Research Council of Italy,Rome, Via Vettore 4.     

Isotope measurements and ground water flow modeling using MODFLOW for understanding environmental changes caused by a well field in semiarid Brazil

Measurements of the environmental isotopes carbon-14 and oxygen-18 and of the electrical conductivity in ground water, together with MODFLOW-88 (DOS) simulations of pumping tests, were used to achieve a detailed understanding of the functioning of an aquifer in the area of a well field. The methodology was applied in the sedimentary basin of the Cariri region, in the south of Ceará State in Brazil. Localized hydraulic connections between adjacent aquifer units could be detected, and mixing ratios for the contributions from the units involved were determined. Cone of depression simulations for a three-year drought period revealed well interference and a drastic lowering of the piezometric level, thereby explaining the hydrogeologic changes and transformations in vegetation that were observed in the area of the well field. The combined use of the modeling tools and the geochemical field observations is shown to provide more detailed insight into the conceptual model of the groundwater flow system.     

Observations of physical effects from tsunamis of December 30, 2002 at Stromboli volcano, southern Italy

On December 30, 2002, following an intense period of activity of Stromboli volcano (south Tyrrhenian Sea, Italy), complex mass failures occurred on the northwest slope of the mountain which also involved the underwater portion of the volcanic edifice for a total volume of about 2–3×10⁷ m³. Two main landslides occurred within a time separation of 7 min, and both set tsunami waves in motion that hit the coasts of Stromboli causing injuries to three people and severe damage to buildings and structures. The tsunamis also caused damage on the island of Panarea, some 20 km to the SSE from the source. They were observed all over the Aeolian archipelago, at the island of Ustica to the west, along the northern Sicily coasts to the south as well as along the Tyrrhenian coasts of Calabria to the east and in Campania to the north. This paper presents field observations that were made in the days and weeks immediately following the events. The results of the quantitative investigations undertaken in the most affected places, namely along the coasts of Stromboli and on the island of Panarea, are reported in order to highlight the dynamics of the attacking waves and their impact on the physical environment, on the coastal structures and on the coastal residential zone. In Stromboli, the tsunami waves were most violent along the northern and northeastern coastal belt between Punta Frontone and the village of Scari, with maximum runup heights of about 11 m measured on the beach of Spiaggia Longa. Measured runups were observed to decay rapidly with distance from the source, typical of tsunami waves generated by limited-area sources such as landslides.     

Groundwater irrigation and its implications for water policy in semiarid countries: the Spanish experience

Over the last decades, groundwater irrigation has become commonplace in many arid and semiarid regions worldwide, including Spain. This is largely a consequence of the advances in drilling and pumping technologies, and of the development of Hydrogeology. Compared with traditional surface water irrigation systems, groundwater irrigation offers more reliable supplies, lesser vulnerability to droughts, and ready accessibility for individual users. Economic forces influence the groundwater irrigation sector and its development. In Spain's Mediterranean regions, abstraction costs often amount to a very small fraction of the value of crops. In the inner areas, groundwater irrigation supports a more stable flow of farm income than rainfed agriculture. The social (jobs/m³) and economic (€/m³) value of groundwater irrigation generally exceeds that of surface water irrigation systems. However, poor groundwater management and legal controversies are currently at the base of Spain's social disputes over water. A thorough and transparent assessment of the relative socio-economic value of groundwater in relation to surface water irrigation might contribute to mitigate or avoid potential future conflicts. Enforcement of the European Union's Water Framework Directive may deliver better groundwater governance and a more sustainable use.

---

Resumen Durante las últimas décadas, la irrigación con agua subterránea se ha vuelto común en muchas regiones áridas y semiáridas alrededor del mundo, incluyendo a España. Ésta es en gran medida una consecuencia de los adelantos en las tecnologías de perforación y bombeo, y del desarrollo de la Hidrogeología. Comparada con los sistemas tradicionales de irrigación con agua superficial, la irrigación con agua subterránea ofrece suministros más fiables, la vulnerabilidad es menor a las sequías, y posee accesibilidad inmediata para los usuarios individuales. Las fuerzas económicas influyen el sector de irrigación con agua subterránea y su desarrollo. En las regiones mediterráneas de España, los costos de extracción suman a menudo una parte muy pequeña del valor de las cosechas. En las áreas internas, la irrigación con agua subterránea constituye un flujo más estable de ingresos para la granja, que la agricultura dependiente del agua lluvia. El valor social (empleos/m³) y económico (€/m³) de la irrigación con agua subterránea, generalmente excede a aquél con sistemas de irrigación de agua superficial. Sin embargo, la gestión pobre del agua subterránea y las controversias legales están actualmente en la base de las disputas sociales en España acerca del agua. Una evaluación completa y transparente del valor socio-económico relativo de agua subterránea respecto a la irrigación con agua superficial, podría contribuir mitigar o evitar los conflictos potenciales del futuro. La entrada en vigor del Marco Reglamentario de Agua de la Unión Europea, puede conllevar a una administración mejor del agua subterránea y a un uso más sostenible.

---

Résumé Depuis les dernières décennies, l’irrigation avec l’eau souterraine est devenue commune dans plusieurs régions arides et semi-arides, incluant l’Espagne. Ceci est largement une conséquence due à l’avancement aux technologies de forages et des pompages, et au développement de l’Hydrogéologie. Comparé avec des systèmes traditionnels d’irrigation utilisant l’eau de surface, l’irrigation avec l’eau souterraine offre une technique d’alimentation plus fiable, une vulnérabilité à la sécheresse moins grande, et une accessibilité plus aisée pour chaque utilisateur. Les forces économiques influencent le secteur de l’irrigation par l’eau souterraine et son développement. Dans les régions de l’Espagne Méditerranéenne, les coûts d’exploitation représentent toujours une petite fraction de la valeur des cultures. Dans les régions intérieures, l’irrigation par l’eau souterraine supporte une agriculture plus stable et continue qu’une agriculture reposant sur l’eau de pluie. La valeur sociale (emploi/m³) et économique (€/m³) de l’irrigation avec l’eau souterraine, excède généralement celle des systèmes d’irrigation avec l’eau de surface. Néanmoins, des gestions pauvres de l’eau souterraine et des controverses légales sont couramment à la base de disputes sociales sur l’eau. Un bilan transparent et minutieux des valeurs relatives socio-économiques de l’eau souterraine en relation avec l’eau de surface d’irrigation, devrait contribuer à éviter de potentiels et futurs conflits. Un renforcement de la Directive Cadre de l’Union Européenne devrait apporter une meilleure gouvernance et un usage plus durable.

     

Millimetric properties of IRAS galaxies – III. Luminosity functions, sub-mm counts and contributions to the sky background

We exploit observations at 1.25 mm with the ESO–SEST telescope of a southern galaxy sample, selected from the IRAS PSC and complete to S ₆₀=2 Jy, to derive the FIR and mm luminosity functions and the conditional probability distributions of FIR and mm luminosity of galaxies. The reliability of these estimates is ensured by the good observed correlation of the far-infrared and mm emissions. This detailed knowledge of the millimetric properties of galaxies is used to simulate the extragalactic sub-mm sky (background intensity, small-scale anisotropy signals and discrete source statistics), which is the target of a variety of ground-based and space observatories. We find, in particular, that a recent tentative detection of a sub-mm background would require, if confirmed, strong evolution with cosmic time of the galaxy long-wavelength emissivity. We finally discuss ways to test such evolution with present and forthcoming facilities: while emphasizing the difficulty of achieving this with large mm telescopes on the ground (because of the poor atmospheric conditions of current sub-mm sites), we mention an interesting opportunity with the long-wavelength camera on ISO . Preliminary results of deep surveys, both from space and from the ground, seem indeed to require excess emission in the past by dusty galaxies with respect to no-evolution predictions.