Improving the determination of reservoir capacities for drought control   总被引：2，自引：2，他引：0  

Aline de Araújo Nunes  Fernando Falco Pruski 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(1):183-191

Reliable methods of determining reservoir capacities are becoming more and more necessary to improve the planning and management of water resources. Due to its easy use and solid technical and scientific basis, the Reservoir Operation Study has been widely utilized by engineers. However, this method is limited by its strong dependence on the available database. This study was undertaken to propose potential modifications to the Reservoir Operation Study to overcome its problems, namely the strong dependence upon the first year of the time series and inability of associating the reservoir storage capacity with a frequency (return period). To make the reservoir capacity independent from the first year of the time series, we created (N ? 1) synthetic series of streamflows (N = the number of years in the time series) and applied the Reservoir Operation Study method to each one. To associate the reservoir capacity with a frequency factor (return period), we applied a Gumbel distribution to the reservoir capacity estimated from each one of the synthetic series. For β-values (proportion of the average streamflow to be regulated) greater than or equal to 0.75, the proposed method efficiently overcame the aforementioned limitation regarding the method’s dependence on the database. The association of storage capacities with return periods greater than the length of the time series, which is presented in this work, also considerably improves the Reservoir Operation Study method.  相似文献   

Reflection on the first five years of South Africa’s Acoustic Tracking Array Platform (ATAP): status,challenges and opportunities     

PD Cowley  RH Bennett  A-R Childs  TS Murray 《African Journal of Marine Science》2017,39(4):363-372

The Acoustic Tracking Array Platform (ATAP) is a marine science programme that monitors the movements and migrations of inshore marine animals along the South African coastline. Acoustically tagged animals are monitored by an expanded network of approximately 100 automated data-logging acoustic receivers moored at strategic node sites, from Cape Point in the west to the South Africa–Mozambique border in the east. During five years since its inception, in 2011, the ATAP has achieved outstanding progress in terms of the numbers of animals and the variety of species tagged. To date, the ATAP has yielded over 2.6 million detections from more than 700 acoustically tagged animals, representing 27 different species from 20 families, including the African penguin Spheniscus demersus, fishery-at-risk species (e.g. dusky kob Argyrosomus japonicus) and iconic elasmobranchs (e.g. white shark Carcharodon carcharias). Following a period of considerable equipment loss in 2014, refinement of the receiver network was required and the deeper receivers at each site were decommissioned without influencing the integrity of the nationwide array. The platform, managed by the South African Institute for Aquatic Biodiversity, ultimately represents a low-cost method of collecting long-term data that currently benefits approximately 25 researchers from 14 organisations. Case studies are presented to expose the opportunities provided by the ATAP, which will undoubtedly yield new discoveries and provide a greater understanding of the movement patterns and migrations of a wide variety of inshore marine and estuary-associated species.  相似文献   

Characterization of a natural magnetite     

A. C. Doriguetto  N. G. Fernandes  A. I. C. Persiano  E. Nunes Filho  J. M. Grenèche  J. D. Fabris 《Physics and Chemistry of Minerals》2003,30(5):249-255

Single crystals of a rock magnetite were separated from steatite cobbles collected in a geological site near the city of Serro (18° 36′ 47′′ S 43° 22′ 46′′ W), Minas Gerais, Brazil. A typically well-shaped magnetite single crystal was characterized by chemical analysis, ⁵⁷Fe Mössbauer spectrometry at 300, 77 and 4 K and under an applied magnetic field of 6 T at 10 K, magnetization measurements and electronic microprobe. From Mössbauer data, the sample is stoichiometric with a tetrahedral and octahedral site occupancy ratio of 1:2. Elemental chemical analysis and point-to-point electron microscope probing show some inclusions of lamellar ilmenite (≤ 1 mass%) randomly distributed throughout the magnetite matrix, and also that the magnetite matrix is constituted only by Fe²⁺ and Fe³⁺, with no isomorphic substitution. Results are discussed on the basis of the magnetization curve and of the temperature dependence of the AC magnetic susceptibility. The Verwey transition occurs in the temperature range of 100–115 K, observed by a sudden change in the temperature dependence of the magnetization.  相似文献   

Acute toxicity of the water-soluble fraction of Cook Inlet crude oil to the Manila clam     

Pepsi Nunes  Pete E. Benville  Jr. 《Marine pollution bulletin》1978,9(12):324-331

Recognition of the inherent complexities of oil bioassays prompted the development of several apparatuses designed to deliver uniform solutions of the water-soluble components of crude oil and capable of system equilibration for both static and continuous-flow bioassays without the loss of the more volatile compounds and without the formation of emulsions. Clams from a relatively contaminated area exhibited greater resistance to the water-soluble fraction of Cook Inlet crude oil than specimens from a more pristine area. Behaviour was altered below lethal levels suggesting the possibility of using behavioural modifications as a concommitant criterion of toxicity with mortality. An increase in mortality with a longer exposure period and a significant rate of latent mortalities following the end of the 96-h exposure period suggest that future bioassays with bivalves should be determined over a longer exposure period.  相似文献   

Moisture relationships for the Southern Hemisphere     

Nandamudi Jagan Mohana Rao  Y. Viswanadham  G. S. S. Nunes 《Pure and Applied Geophysics》1980,118(2):1076-1089

Values for mean precipitable water are computed for four seasons of the year and for different regions of the Southern Hemisphere. Relationships between surface dew-point temperature and precipitable water were studied for these regions. A harmonic analysis of our data on precipitable water is attempted. Out results are presented and discussed.  相似文献   

The age of the Stillwater complex—a comparison of U-Pb zircon and Sm-Nd isochron systematics     

P.D. Nunes 《Geochimica et cosmochimica acta》1981,45(10):1961-1963

A zircon U-Pb age of 2713 ± 3 Myr confirms the less precise age of about 2710 Myr (corrected for new decay constants of Jaffeyet al., 1971) obtained from the same sample of zircon from the Stillwater complex chill zone (Nunes and Tilton, 1971). This age compares with Sm-Nd mineral and whole-rock isochron ages of 2701 ± 8 Myr (Depaolo and Wasserburg, 1979); or 2706 ± 8 Myr if the Lugmairet al. (1975) normalization procedure is used. The agreement of these ages to within about 0.4% indicates that the λ₁₄₇ = 0.00654 × 10^?9yr^?1 value is less than 0.8% too large relative to the U decay constants determined by Jaffeyet al. (1971) and enables more correct geological syntheses to be made when working out detailed absolute age stratigraphies using precise data from both systems.  相似文献   

Biodiversity and its conservation in the Pantanal of Mato Grosso, Brazil   总被引：1，自引：1，他引：1  

Wolfgang J. Junk  Catia Nunes da Cunha  Karl Matthias Wantzen  Peter Petermann  Christine Strüssmann  Marinêz Isaac Marques  Joachim Adis 《Aquatic Sciences - Research Across Boundaries》2006,68(3):278-309

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Gravimetric determination of an intrusive complex under the Island of Faial (Azores): some methodological improvements   总被引：2，自引：0，他引：2  

Antonio G. Camacho  J. Carlos Nunes  Esther Ortiz  Zilda França  Ricardo Vieira 《Geophysical Journal International》2007,171(1):478-494

We present some improvements of a gravity inversion method to determine the geometry of the anomalous bodies for priori density contrasts. The 3-D method is based on an exploratory process applied, not for the global model, but for the steps of a growth approach. The (positive and/or negative) anomalous structure is described by successive aggregation of cells, while its corresponding gravity field remains nearly proportional to the observed one. Moreover, a simple (e.g. linear) regional trend can be simultaneously adjusted. The corresponding program is applied to new gravity data on the volcanic island of Faial (Azores archipelago). The inversion approach shows a subsurface anomalous structure for the island, the main feature being an elongated high-density body. The body is interpreted as a compact sheeted dyke swarm, emplaced along Faial-Pico Fracture Zone, a leaky transform structure that forms the current boundary between Eurasian and African plates in the Azores area. The new results in this paper are (1) a Bouguer gravity anomaly map, (2) several improvements in the inversion process (robust process, optimal balance fitness/model magnitude), (3) a new gravimetric method for estimating the mean terrain density, (4) a 3-D model for subsurface mass anomalies in Faial and (5) some interpretative conclusions about a main intrusive complex detected under the island as a wall-like structure extending from a depth of 0.5 to 6 km b.s.l., with a N100°E trend and corresponding to an early fissural volcanic episode controlled by the regional tectonics.  相似文献   

Bedrock bedding,landsliding and erosional budgets in the Central European Alps   总被引：4，自引：0，他引：4       下载免费PDF全文

Fábio Cruz Nunes  Romain Delunel  Fritz Schlunegger  Naki Akçar  Peter W. Kubik 《地学学报》2015,27(5):370-378

We explore the controls of the litho‐tectonic architecture on the erosional flux in the 370‐km² Glogn basin (European Alps). In this basin, the bedding and schistosity of the bedrock dip parallel to the topographic slope on the NW valley flank, leading to a non‐dip slope situation on the opposite SE valley side. While the dip slope condition has promoted the occurrence of landslides (e.g. the c. 30‐km² deep‐seated Lumnezia landslide), the opposite non‐dip slope side of the valley hosts >100‐m‐deeply incised tributary streams. ¹⁰Be concentrations of stream sediments yield catchment‐averaged denudation rates that vary between 0.27 ± 0.03 and 2.19 ± 0.37 mm a^?1, while the spatially averaged denudation rate of the entire basin is 1.99 ± 0.34 mm a^?1. Our ¹⁰Be‐based approach reveals that the Lumnezia landslide front contributes c. 30–65% of the entire sediment budget, although it covers <5% of the Glogn basin. This suggests a primary control of the bedrock bedding on erosion rates and processes.  相似文献   

Better models are more effectively connected models   总被引：1，自引：0，他引：1       下载免费PDF全文

Connecteur WG Think‐Tank Team  Jo?o Pedro Nunes  John Wainwright  Charles L. Bielders  Frédéric Darboux  Peter Fiener  David Finger  Laura Turnbull 《地球表面变化过程与地形》2018,43(6):1355-1360

Water‐ and sediment‐transfer models are commonly used to explain or predict patterns in the landscape at scales different from those at which observations are available. These patterns are often the result of emergent properties that occur because processes of water and sediment transfer are connected in different ways. Recent advances in geomorphology suggest that it is important to consider, at a specific spatio‐temporal scale, the structural connectivity of system properties that control processes, and the functional connectivity resulting from the way those processes operate and evolve through time. We argue that a more careful consideration of how structural and functional connectivity are represented in models should lead to more robust models that are appropriate for the scale of application and provide results that can be upscaled. This approach is necessary because, notwithstanding the significant advances in computer power in recent years, many geomorphic models are still unable to represent the landscape in sufficient detail to allow all connectivity to emerge. It is important to go beyond the simple representation of structural connectivity elements and allow the dynamics of processes to be represented, for example by using a connectivity function. This commentary aims to show how a better representation of connectivity in models can be achieved, by considering the sorts of landscape features present, and whether these features can be represented explicitly in the model spatial structure, or must be represented implicitly at the subgrid scale. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献