Hydrodynamic and isotopic investigations for evaluating the mechanisms and amount of groundwater seepage through a rockslide dam

This study addresses the influence of landslide dams on surface water drainage and groundwater flow. In the study area of Scanno Lake and Sagittario River (Central Italy), a limestone rockslide‐avalanche formed a lake, which has an outlet that is occasionally active, showing infiltration into the rockslide dam. Several springs are present at the lake's base and are partly fed by seepage through the rockslide debris. Piezometric surveys, discharge measurements, pumping tests and chemical analyses are tools used to build a conceptual model of the groundwater flow and to evaluate the flow through the rockslide debris. Seasonal water isotopic signatures validate the assumed model, showing a mixing of infiltration recharge and groundwater seepage throughout the rockslide debris. Various recharge areas have been found for springs, pointing out those directly fed by the rockslide debris aquifer. Hypotheses about seasonal groundwater mixing between the regional carbonate aquifer and the rockslide debris aquifer are supported by isotope results. Seasonal changes in groundwater table level due to recharge and surface losses from seasonal outlet have been correlated with isotopic groundwater composition from the rockslide debris aquifer and the downstream springs; this relationship highlights the role of the rockslide dam body on the hydrodynamics of the studied area. Relationships between surface waters and groundwater in the area have been completely understood on the basis of water isotopic fingerprinting, finally obtaining a complete evaluation of groundwater renewable resources and its regimen. Copyright © 2010 John Wiley & Sons, Ltd.     

Rappresentazioni parziali e totali dell’ellissoide di rotazione sulla sfera

Riassunto L’A., partendo dall’idea di minimizzare l’energia di deformazione della rete geografica ellissoidica, supposta elastica, per adattarla a una sfera, determina una corrispondenza fra l’ellissoide di rotazione e la sfera locale in un intorno del punto di osculazione fino a 250 km di raggio. Ne risultano semplici formule per le correzioni angolari ai limiti dell’intorno e per la trasformazione delle coordinate. Successivamente l’A. sottopone a un esame critico varie funzioni che, estremate, dànno luogo a buone rappresentazioni dell’intero ellissoide sulla sfera ed introduce una nuova latitudine, utile per la costruzione di carte geografiche globulari, che risulta media fra la latitudine geocentrica e quella ridotta.

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Summary The Author, starting from the idea of minimizing the deformation energy of the ellipsoidic geographical network, which he supposes to be perfectly elastic in order to adapt it to a sphere, determines a correspondence between the rotation ellipsoid and the local sphere in the neighbourhood of the osculation point, to the distance of 250 km. He hereby deduces simple formulas for the angular corrections in the border of the neighbourhood and for appropriate transformation of coordinates. In the second part the A. takes into critical examination some functions, which, minimized, afford good representation of the whole ellipsoid on the sphere; he also introduces a new latitude that is revealed useful for the construction of globular geographical maps and numerically can be considered as a mean between the geocentric latitude and the reduced one.

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Dr.Carlo Bernasconi, Istituto Geofisico e Geodetico dell’Università diGenova.     

Sulle formule per le osservazioni di differente precisione sopra una medesima grandezza e sulla compensazione rigorosa di misure miste lineari e angolari

Riassunto L'A., partendo dal principio che un sistema di osservazioni di diversa precisione è riducibile a un sistema di osservazioni di uguale precisione, propone una nuova formula per la valutazione dell'errore medio dell'unità di peso. Tale formula non si annulla nel caso di misure che, pur essendo di peso diverso, sono uguali fra loro. — Nella seconda parte l'A. avanza l'ipotesi che un aspetto geometrico della compensazione di misure miste sia quello di trasformare una figura in un'altra, soddisfacente prefissate condizioni, con un minimo di deformazione; ritiene che tale minimo possa anche non essere dato da una combinazione lineare dei quadrati degli errori lineari e angolari.

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Summary Basing himself on the principle that a system of observations of different precision may be reduced to a system of observations of the same precision, the Author proposes a new formula for a valuation of the standard error of the weight unit. Such formula is not nullified in case of measurements which, though of different weights, are equal. — In the second part the Author puts forward the hypothesis that a geometric aspect of the compensation of different kinds of measures, is of transforming a figure, wich satisfies given conditions, into another by the least deformation. He believes that such least deformation may be obtained without making a linear combination of linear and angular squared errors.

     

Inconstancy in predator/prey ratios in Quaternary large mammal communities of Italy, with an appraisal of mechanisms

Constancy in predator/prey ratio (PPR) is a controversial issue in ecological research. Published reports support both constancy and inconstancy of the ratio in animal communities. Only a few studies, however, specifically address its course through time. Here we study the course of predator/prey ratio in communities of large Plio-Pleistocene mammals in Italy. After controlling for taphonomic biases, we find strong support for PPR inconstancy through time. Extinction, dispersal events, and differences in body size trends between predators and their prey were found to affect the ratio, which was distributed almost bimodally. We suggest that this stepwise dynamic in PPR indicates changes in ecosystem functioning. Prey richness was controlled by predation when PPR was high and by resources when PPR was low.     

Geochemistry of silicic magmas in the Macolod Corridor, SW Luzon, Philippines: evidence of distinct, mantle-derived, crustal sources for silicic magmas

Silicic volcanic deposits (>65 wt% SiO₂), which occur as domes, lavas and pyroclastic deposits, are relatively abundant in the Macolod Corridor, SW Luzon, Philippines. At Makiling stratovolcano, silicic domes occur along the margins of the volcano and are chemically similar to the silicic lavas that comprise part of the volcano. Pyroclastic flows are associated with the Laguna de Bay Caldera and these are chemically distinct from the domes and lavas at Makiling stratovolcano. As a whole, samples from the Laguna de Bay Caldera contain lower concentrations of MgO and higher concentrations of Fe₂O_3(t) than the samples from domes and lavas. The Laguna de Bay samples are more enriched in incompatible trace elements. The silicic rocks from the domes, Makiling Volcano and Laguna de Bay Caldera all contain high alkalis and high K₂O/Na₂O ratios. Melting experiments of primitive basalts and andesites demonstrate that it is difficult to produce high K₂O/Na₂O silicic magmas by fractional crystallization or partial melting of a low K₂O/Na₂O source. However, recent melting experiments (Sisson et al., Contrib Mineral Petrol 148:635–661, 2005) demonstrate that extreme fractional crystallization or partial melting of K-rich basalts can produce these silicic magmas. Our model for the generation of the silicic magmas in the Macolod Corridor requires partial melting of mantle-derived, evolved, moderate to K-rich, crystallized calc-alkaline magmas that ponded and crystallized in the mid-crust. Major and trace element variations, along with oxygen isotopes and ages of the deposits, are consistent with this model. Electronic Supplementary Material Supplementary material is available for this article at     

A new insight into land use classification based on aggregated mobile phone data

Land-use classification is essential for urban planning. Urban land-use types can be differentiated either by their physical characteristics (such as reflectivity and texture) or social functions. Remote sensing techniques have been recognized as a vital method for urban land-use classification because of their ability to capture the physical characteristics of land use. Although significant progress has been achieved in remote sensing methods designed for urban land-use classification, most techniques focus on physical characteristics, whereas knowledge of social functions is not adequately used. Owing to the wide usage of mobile phones, the activities of residents, which can be retrieved from the mobile phone data, can be determined in order to indicate the social function of land use. This could bring about the opportunity to derive land-use information from mobile phone data. To verify the application of this new data source to urban land-use classification, we first construct a vector of aggregated mobile phone data to characterize land-use types. This vector is composed of two aspects: the normalized hourly call volume and the total call volume. A semi-supervised fuzzy c-means clustering approach is then applied to infer the land-use types. The method is validated using mobile phone data collected in Singapore. Land use is determined with a detection rate of 58.03%. An analysis of the land-use classification results shows that the detection rate decreases as the heterogeneity of land use increases, and increases as the density of cell phone towers increases.     

Rappresentazione di curve spaziali materializzate

Riassunto Per rappresentare una curva spaziale su un piano si può piegare un filo metallico secondo la curva e fotografarlo, operazione che però richiede molto tempo. Nel presente articolo l'A. illustra un dispositivo ottico che, sostituito alla matita della tavola di egresso della macchina diBush, è atto a descrivere su pellicola una curva simile all'immagine fotografica del filo. In questo studio si sono considerati soltanto i casi in cui la sorgente di luce che illumina la è all'infinito o nella origine delle coordinate, mentre il punto di vista à sempre all'infinito.

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Summary One may represent a spatial curve on a plane by bending a metal thread along the curve and then photographing it, but in this way much time is wasted. In the present paper the A. suggests an optical device which, replaced to the pencil of the out-put table ofBush's machine, traces on film a curve that should look like the photographic image of the thread. In this study were taken into account only the cases in which the light source lighting , is at the infinite or in the coordinate origin, while the point of view is always at the infinite.