Passing volume calculation system (PVCS): computer software for managing data on watersheds that produce mud flows and the case of Quebrada La Cadena,Antofagasta, Chile

Severe storms in desert regions, especially along the coastal area of the Chilean desert, produce very destructive mud flows that last a few hours and constitute the only surface run-off in these events. To date, there is no simple or practical methodology for assessing such mud flows. Given the settlement of mining fields and creation of desert campgrounds, it is increasingly necessary to understand how these water and/or mud flows behave in order to develop structural and non-structural mitigation plans. Thus, herein, we present software known as PVCS, which provides a system for calculating mud volumes after a strong storm. This hydrological and computer tool allows us to calculate the structure and volume of mud passing through the mouth of a hydrographic watershed after a desert rainstorm. To use this software, it is necessary to know the hydrological, meteorological, and morphometric parameters of the watershed under study. These data are entered into a model that estimates the amount of mud that will pass through the mouth with each hour of rain. Simulations can be done with historical data or data designed for future events, thereby allowing the preparation of measures to protect people and property. We use the watershed Quebrada La Cadena to exemplify the use of this software. This drainage basin is located on the western slope of the Chilean Coastal Range in Antofagasta, a city in northern Chile. Here, rain in June 1991 produced a destructive flood that killed nearly one hundred people living at the main mouth of the watershed and caused huge economic losses. Data from this catastrophe have significantly improved the understanding of such flows, and this has been incorporated into the software. The principal value of PVCS lies in its ability to forecast the volume of mud that will result from a storm and hourly outflows that will pass through a specific populated area, mining camp, or industrial plant located in the mouth of a watershed of any size. This information is used to determine the most critical moment, i.e., the time of the largest outflows, which can then be used to organize timely evacuations to safe places for people, animals, and machines. Moreover, the program is methodologically valuable since, in order to implement PVCS, the user must structure information in a hydrological way. In summary, this program simulates different rain scenarios, thereby allowing us to design structural mitigation projects and contingency plans.     

Global sensitivity analysis of hydrologic processes in major snow‐dominated mountainous river basins in Colorado

The performance of watershed models in simulating stream discharge depends on the adequate representation of important watershed processes. In snow‐dominated systems, snow, surface and subsurface hydrologic processes comprise a complex network of nonlinear interactions that influence the magnitude and timing of discharge. This study aims to identify critical processes and interactions that control discharge hydrographs in five major mountainous snow‐dominated river basins in Colorado, USA. A comprehensive watershed model (Soil and Water Assessment Tool) and a variance‐based global sensitivity analysis technique (Fourier Amplitude Sensitivity Test) were used in conjunction to identify critical models parameters and processes that they represent. Average monthly streamflow and streamflow root mean square error over a period of 20 years were used as two separate objective functions in this analysis. Examination of the sensitivity of monthly streamflow revealed the influence of parameters on flow volume, whereas the sensitivity of streamflow root mean square error also exposed the influence of parameters on the timing of the hydrographs. A stability analysis was performed to investigate the computational requirements for a robust sensitivity analysis. Results show that streamflow volume is mostly influenced by shallow subsurface processes, whereas interactions between groundwater and snow processes were the key in the timing of streamflows. A large majority of important parameters were common among all study watersheds, which underlies the prospect for regionalization of process‐based hydrologic modelling in headwater river basins in Colorado. Copyright © 2013 John Wiley & Sons, Ltd.     

A merger tree with microsolar mass resolution: application to γ-ray emission from subhalo population

Observations of the southern Cepheid ℓ Car to yield the mean angular diameter and angular pulsation amplitude have been made with the Sydney University Stellar Interferometer at a wavelength of 696 nm. The resulting mean limb-darkened angular diameter is 2.990 ± 0.017 mas (i.e. ± 0.6 per cent) with a maximum-to-minimum amplitude of 0.560 ± 0.018 mas corresponding to 18.7 ± 0.6 per cent in the mean stellar diameter. Careful attention has been paid to uncertainties, including those in measurements, in the adopted calibrator angular diameters, in the projected values of visibility squared at zero baseline, and to systematic effects. No evidence was found for a circumstellar envelope at 696 nm. The interferometric results have been combined with radial displacements of the stellar atmosphere derived from selected radial velocity data taken from the literature to determine the distance and mean diameter of ℓ Car. The distance is determined to be 525 ± 26 pc and the mean radius  169 ± 8 R_⊙  . Comparison with published values for the distance and mean radius shows excellent agreement, particularly when a common scaling factor from observed radial velocity to pulsation velocity of the stellar atmosphere (the p -factor) is used.     

Environmental impacts and simultaneity of positive and negative storm surges on the coast of the Province of Buenos Aires, Argentina

The Argentine shore of the Rio de la Plata estuary and its southwards adjacent maritime front are normally affected by extratropical positive and negative storm surges that affect human activities seriously. Positive surges can raise the water level in the estuary by more than 3 m over the predicted tide; thus, flooding the coastal plain where over 13 million people live and causing extensive property damage. Sometimes, there has been loss of life too. Although less populated than the coastal plain, the maritime front has many important tourist resorts and also undergoes severe beach erosion processes and loss of property owing to positive surges. Negative surges are particularly troublesome in the Rio de la Plata because they critically affect navigation safety and drinking water supply by lowering the predicted water level in an amount that sometimes reached more than 4 m. A remarkable point is that the same storm event can simultaneously give rise to a positive surge on the maritime front and a negative one in the Rio de la Plata. The environmental impacts of positive storm surges are strongly aggravated by human intervention. At the same time, sea level rise due to global climatic change has also its influence.     

First definitive observations of meteor shower particles using a high-power large-aperture radar

We present the first clear observations of meteor shower activity from meteor-head echoes detected by a high-power large-aperture radar (HPLAR). Such observations have been performed at the Jicamarca VHF radar using its interferometric capabilities allowing the discrimination of meteor shower echoes from the much more frequent sporadic meteors. Until now, HPLARs were unable to distinguish meteor shower from the much more common sporadic meteor ones. In this work we have been able to detect and characterize the η-Aquariids (ETA) as well as the Perseids (PER) showers. The shower activity is more conspicuous for the ETA than for the PER shower due to the more favorable geometry. Namely, PER meteors come from low elevation angles, experiencing more filtering due to the combined Earth-atmosphere-radar instrument. In both cases, there is an excellent agreement between the measured mean velocity of the shower echoes and their expected velocity, within a fraction of 1 km s⁻¹. Besides the good agreement with expected visual results, HPLARs observe meteors with a variety of particles sizes and masses, not observed by any other technique. Taking into account the different viewing volumes, compare to optical observations Jicamarca observes more than 1000 times more ETA meteors. Our results indicate that Jicamarca and other HPLARs are able to detect the echoes from meteor showers, but without interferometric capabilities such populations are difficult to identify just from their velocity distributions, particularly if their velocity distributions are expected to be similar to the more dominant distributions of sporadic meteors.     

Remarks on the one-photon-pair annihilation in strong magnetic fields

We report specifically on a quantum electrodynamic feature of the one-photon-pair annihilation. Most of the calculation related with this process (not excluding other ones) have been carried out usually utilizing the wave functions obtained from the Dirac equation in the Landau gauge A = (0,Bx, 0), where B is oriented along the z-axis (Johnson and Lippman, 1949). Although, the eigenstates of the Dirac Hamiltonian as it was introduced by Johnson and Lippman, do not consider the coupling to the radiation field and consequently they reflect only forp _z = 0 the same linear combination of the two degenerate polarization states.We report the transition rate function for the one-photon-pair annihilation in a strong magnetic field by using the Sokolov and Ternov eigenstate |± as far asp _z = 0 andN > 0 is concerned. The difference between the expression for the transition rate by using the Sokolov and Ternov eigenstates and the one calculated by (Wunneret al., 1986), is just the functionI _s,s which corresponds to the degeneracy of the orbit center of the electrons characterized by the quantum numberss ands. Presented at the 2nd UN/ESA Workshop, held in Bogotá, Colombia, 9-13 November, 1992.     

Le Batholite de San Ramon,Cordillère Orientale du Pérou Central

Résumè Le batholite de San Ramon est constitue par un granite à gros grains ou porphyroïde, à biotite et parfois hornblende, de teinte rouge à grise. Il s'étend sur 90 km du Nord au Sud à la bordure est de la Cordillère Orientale du Pérou Central. Il recoupe des terrains carbonifères et on le retrouve en galets dans des conglomérats rouges sous-jacents aux calcaires triasico-liasiques. Son âge est précisé par une isochrone Rb/Sr en roches totales qui le fixe à 238±10 MA. Il s'agit donc d'un granite d'âge permien supérieur à trias inférieur en partie contemporain du volcanisme rhyolitique à andésitique qui accompagne le dépôt des molasses rouges Mitu post-léonardiennes et pré-ladiniennes. Avec d'autre granitoïdes tardi-hercyniens de la Cordillère Orientale, il témoigne de l'importance insuffisamment reconnue jusqu'alors du plutonisme associé à ce volcanisme »permo-triasique«.

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The batholith of San Ramon is made of a coarse-grained to porphyritic granite that bears biotite and also hornblende at some places. It extends over 90 km from north to south along the eastern boundary of the Eastern Cordillera of Central Peru. It intrudes Carboniferous and Lower Permian strata and is included as cobbles into the red conglomerates that underlie Triassic to Liassic carbonates. A Rb/Sr whole-rock isochron gives a Late Permian to Early Triassic age of 238±10 m. y. Thus the San Ramon granite appears to be in part coeval with the andesite to rhyolitic volcanism associated to the red Mitu molasses, that as a whole were deposited after the Late Leonardian and before the Lower Ladinian. Some other radiometric ages from the Eastern Cordillera granitoïds stress the extension of this Late Variscan plutonism.

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Zusammenfassung Der Batholit von San Ramon besteht aus einem grobkörnigen bis porphyrartigen Granit mit Biotiten und bisweilen Hornblenden von rötlicher bis grauer Farbe. Er erstreckt sich über 90 km in N—S-Richtung längs dem Ostrand der östlichen Cordillere von Zentralperu. Er durchschneidet Karbon- und Permablagerungen und findet sich in Gerollen des triadisch-liassische Kalke unterlagernden Konglomerats. Aus der Rb/Sr-Gesamtisochrone ergibt sich ein Alter von 238±10 M. J. Es handelt sich also um einen Granit aus dem Grenzbereich Perm—Trias, der zum Teil gleichaltrig mit dem rhyolitischen bis andesitischen Vulkanismus ist, der die Ablagerung der postleonardischen und praeladinischen roten Molasse Mitubegleitet. Im Verein mit anderen spätvariszischen Granitoïden weist er auf die bisher ungenügend erkannte Bedeutung des diesen permo-triadischen Vulkanismus begleitenden Plutonismus hin.

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Resumen El batolito de San Ramón esta localizado a lo largo del limite este de la Cordillera Oriental en el Perú Central. Esta compuesto por un granito de grano grueso que puede tambien ser porfiroide, contiene biotita y tambien hornablenda y su color varia de rojo a gris. Dicho granito intruye terrenos carboniferos y eo-pérmicos y se le encuentra formando parte de los cantos en los conglomerados rojos infrayacentes a la serie carbonatada triásico-liásica. Una isocrona Rb/Sr en rocas totales le da una edad de 238±10 m. y. es decir del Permico terminal o de la base del Triásico. Por lo tanto, el granito de San Ramón es contemporáneo con parte del volcanismo riolitico a andesítico asociado a la sedimentacion de las molasas rojas del grupo Mitu, la cual ocure entre el Leonardiano superior y el Ladiniano inferior. Junto con otros granitoïdes de la Cordillera oriental, el batolito de San Ramón demuestra la importancia del plutonismo asociado a este volcanismo »permo-triásico«.

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The structure and function of dry weather mangroves on the Pacific Coast of Central America,with emphasis onAvicennia bicolor forests

Mangrove forests along the Pacific Coast of Central America cover around 4,000 km². Most of this coast is occupied with tropical dry forest mangroves where basal areas range between 6 and 20 m² ha^?1 and canopy heights rarely exceed 20 m. Rainfall and runoff alter structure and floristic composition from site to site. Reproductive phenology and mortality appear to be related to soil water availability.Avicennia bicolor forests reach a density of 4,350 plants that are taller than 0.50 m ha^?1, with 769 trees above 5 cm diameter at breast height A total basal area of 41 m² ha^?1 together with a canopy height of about 23 m place these forests among the most developed in the western hemisphere. Growth rate (0.38 m² ha^?1 yr^?1) is surprisingly high for mangrove forests under a seasonal dry climate.     

Treatment of Acid Mine Drainage (AMD) in South Brazil: Comparative active processes and water reuse

This work describes AMD techniques of neutralization, with lime, flocculation of the precipitates and comparative flocs/liquid separation by flotation with microbubbles or by lamellar settling (LS). The AMD treated water was characterized by its quality for recycling in terms of inorganic or organic elements, suspended or dissolved solids, among others. Two types of flocs were formed, “aerated” or not, in a special flocculation reactor, patented by this research group (RGF^®). Aerated flocs formed (within seconds) entered into contact with microbubbles under high shearing and raised-up at rates > 120 mh^− 1 allowing a rapid solid–liquid separation by flotation (HR-high rate), at about 13–15 m³m^− 2 h^− 1 loading capacity. Conversely, the non-aerated flocs settled at about 5–6 m h^− 1 in a lamella settler. Both AMD treatment techniques showed similar efficiencies (removal of ions > 90%) but the separation by lamella settling presented advantages, namely less reagents (no flotation collector required), lower power requirements and easier to operate. The operating costs (approximate values) of the AMD treatment by LS at pH 9 reaches about 0.3 US$ m^− 3 against 0.6 US$ m^− 3 for the HR-flotation process. Results found were proved to be similar to those found in recent ADM treatment installations in South Brazil. The quality of the treated water is fairly good, nearly free of heavy metals ion, low BOD (biological oxygen demand) and TOC (total organic content), low solids content and may be readily reused for irrigation, industrial processes and as wash water (among others, streets, vehicles, dust control). However, there is a need to extend the use of this treated water resource, but this, at least in Brazil, has not been legislated properly. It is concluded that this research will contribute in the discussion of this old and complex problem in acid mining effluents worldwide.