Catastrophic,rainfall-induced debris flows in Andean villages of Tarapacá, Atacama Desert,northern Chile   总被引：1，自引：0，他引：1  

Sergio A. Sepúlveda  Sofía Rebolledo  James McPhee  Marisol Lara  Mauricio Cartes  Eduardo Rubio  David Silva  Nicolle Correia  Juan P. Vásquez 《Landslides》2014,11(3):481-491

In March 2012, during the rainy season in the Altiplano plateau, a >100-year return period rainfall event affected the deeply incised valleys of the Precordillera of the Tarapacá Region, northern Chile. This extreme event in a very arid region triggered a number of debris and mud flows that caused severe damage and destruction in several small villages along the Camiña and Tarapacá valleys. The highly vulnerable location of the villages on top of alluvial fans due to socioeconomic and cultural reasons is a key factor to explain the level of destruction in most villages. In this paper, this unusual, remarkable landslide event is described, and the hazard faced by these settlements for future rainfall episodes and possible mitigation measures are discussed.  相似文献   

Human alteration of groundwater–surface water interactions (Sagittario River,Central Italy): implication for flow regime,contaminant fate and invertebrate response     

Mariachiara Caschetto  Maurizio Barbieri  Diana M. P. Galassi  Lucia Mastrorillo  Sergio Rusi  Fabio Stoch  Alessia Di Cioccio  Marco Petitta 《Environmental Earth Sciences》2014,71(4):1791-1807

Many rivers worldwide are undergoing severe man-induced alterations which are reflected also in changes of the degree of connectivity between surface waters and groundwater. Pollution, irrigation withdrawal, alteration of freshwater flows, road construction, surface water diversion, soil erosion in agriculture, deforestation and dam building have led to some irreversible species losses and severe changes in community composition of freshwater ecosystems. Taking into account the impact of damming and flow diversion on natural river discharge, the present study is aimed at (i) evaluating the effects of anthropogenic changes on groundwater/surface water interactions; (ii) analyzing the fate of nitrogenous pollutants at the floodplain scale; and (iii) describing the overall response of invertebrate assemblages to such changes. Hydrogeological, geochemical and isotopic data revealed short- and long-term changes in hydrology, allowing the assessment of the hydrogeological setting and the evaluation of potential contamination by nitrogen compounds. Water isotopes allowed distinguishing a shallow aquifer locally fed by zenithal recharge and river losses, and a deeper aquifer/aquitard system fed by surrounding carbonate aquifers. This system was found to retain ammonium and, through the shallow aquifer, release it in surface running waters via the hyporheic zone of the riverbed. All these factors influence river ecosystem health. As many environmental drivers entered in action offering a multiple-component artificial environment, a clear relationship between river flow alteration and benthic and hyporheic invertebrate diversity was not found, being species response driven by the combination of three main stressors: ammonium pollution, man-induced changes in river morphology and altered discharge regime.  相似文献   

Preliminary Photometric Evidence of Starspot Umbrae and Penumbrae on Late-Type Active Stars     

Sergio Messina  Edward F. Guinan 《Astrophysics and Space Science》2006,304(1-4):191-193

We constrain the properties of the spotted regions on the photosphere of the active late-type star DX Leonis by comparing the observed amplitudes of light and color variations with synthetic amplitudes obtained by means of Dorren's spot model and computed for a grid of values of spot temperatures, areas and latitudes.  相似文献   

Non-equilibrium beta processes in neutron stars: a relationship between the net reaction rate and the total emissivity of neutrinos     

Sergio Flores-Tulián  Andreas Reisenegger 《Monthly notices of the Royal Astronomical Society》2006,372(1):276-278

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Cosmological implications of COBE's results     

Sergio Torres 《Astrophysics and Space Science》1994,214(1-2):115-126

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Diagenetic evolution of Aptian evaporites in the Namibe Basin (south‐west Angola)          下载免费PDF全文

Laurent Gindre‐Chanu  John K. Warren  Cai Puigdefabregas  Ian R. Sharp  David C. P. Peacock  Roger Swart  Ragnar Poulsen  Hercinda Ferreira  Lourenco Henrique 《Sedimentology》2015,62(1):204-233

The widespread and dissected nature of the Angolan gypsiferous salt residuals offers a uniquely detailed view of the lateral and vertical relations inherent to secondary evaporite textures, which typify exhumed salt masses worldwide. Such secondary textures are sometimes misinterpreted as primary evaporite textures. Thin, metre‐scale and patchy, dome‐like gypsum accumulations are well‐exposed within strongly incised present‐day river valleys along the eastern margin of the Namibe and Benguela basins (south‐west Angola). These sections are time equivalent to the main basinward subsurface evaporites (Aptian Loeme Formation) which mostly consist of halite. The gypsum (here called the Bambata Formation) is interpreted to represent the final residual product of fractional dissolution and recrystallization of the halite mass that occurred during Late Cretaceous margin uplift and continues today. This halite underwent multiple episodes of diagenetic alteration between its deposition and its final exhumation, leading to the formation of various secondary gypsum fabrics and solution‐related karst and breccia textures that typify the current evaporite outcrop. Four different diagenetic gypsum fabrics are defined: thinly bedded alabastrine, nodular alabastrine, displacive selenite rosettes and fibrous satin‐spar gypsum. Current arid conditions are responsible for a thin weathered crust developed at the top of the outcropping gypsum, but the fabrics in the main core of the current at‐surface evaporite unit mostly formed during the telogenetic stage of uplift prior to complete subaerial exposure. Alteration occurred as various dissolving and rehydrating saline minerals encountered shallow aquifers in the active phreatic and vadose zones. Geomorphological and petrographic analyses, mostly based on the cross‐cutting relations and crystallographic patterns in the outcrop, are used to propose a sequence of formation of these different fabrics.  相似文献   

The low-luminosity galaxy population in the NGC 5044 Group     

Sergio A. Cellone  Alberto Buzzoni 《Monthly notices of the Royal Astronomical Society》2005,356(1):41-53

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Earthquake Magnitude Transition Probability and Causal Dependence for Mexico City Earthquakes     

Sergio G. Ferraes 《Geophysical Journal International》1974,38(2):315-316

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The COBE-DMR database and how to use it     

Sergio Torres 《Astrophysics and Space Science》1995,228(1-2):309-312

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The multifunction photoelectric photometer of Torino Observatory     

Sergio Furlani  Giorgio Sedmak 《Astrophysics and Space Science》1977,48(1):65-78

The paper describes the design and the realization of a multiple-function photoelectric photometer made by Trieste Observatory for Torino Observatory. The system design shows a two-beam, sequential multiband photon counting and analog photoelectric photometer configuration based on a PDP8/E computer for the control and data acquisition and elaboration. The actual realization of the system and the use of it in the one-beam configuration operating now at torino Observatory shows the advantages of such a solution and the easiness in modifying and determining the system functions by software programs rather than by hardware specials. Work supported by Consiglio Nazionale delle Ricerche, Gruppo Nazionale di Astronomia, Settore Tecnologie Astronomiche. The realization of the machine was fully supported by Torino Observatory. Trieste Observatory-Instruments and Data Processing Group (5/76).  相似文献