Analysis of the 1 November 2015 heavy rainfall episode in Algarve by using weather radar and rain gauge data     

Sérgio Barbosa  Álvaro Silva  Paulo Narciso 《Natural Hazards》2018,93(1):61-76

The trigger for the study presented in this paper was the extreme rain event of 1 November 2015 in Algarve region. The main objective was the analysis and improvement of the precipitation field using a radar–rain gauge merging method. Ordinary kriging with radar-based error correction has been applied to hourly values of precipitation from both sensors. The merging technique allowed keeping the better radar spatial pattern, being the respective estimates corrected by the rain gauges observations. The procedure led to a reduction in the errors of the precipitation estimates, evaluated by cross-validation, when compared to univariate interpolation of rain gauge observation or radar rain product. Finally, some discussion is also added on the problematic of flooding in urban areas, especially those with absent or deficient urban planning.  相似文献   

Standardization of a NaI(Tl) scintillation detector and its use on environments for Geology teaching in a Brazilian university     

Eder Queiroz Barbosa  Daniel Marcos Bonotto  Gabrielle Roveratti 《Environmental Earth Sciences》2018,77(3):113

This paper describes analytical protocols adopted for calibrating a portable gamma rays spectrometer using a 2? × 2? NaI(Tl) scintillation detector for performing exploration and environmental surveys. The steps involved the determination of counting times with good accuracy, calibration in energy and concentration, and data conversion to effective dose (Ed) for monitoring the radioactivity levels in the air, for indoor and outdoor environments. The χ² test was applied to the counting rate data acquired for ten different readings, allowing determine the greater accuracy among them. Some standards yielded values above of the detection limit for calibrating the K, eU, and eTh windows, whereas empirical equations provided satisfactory results. The count rates in these windows were obtained in selected environments related to Geology teaching activities in a Brazilian university. Then, they were converted to Ed, showing the applicability of the adopted procedures for environmental surveys. The radiological monitoring showed two sites exhibiting Ed values above the WHO guideline reference value of 1 mSv/year. The first was in a minerals and rocks museum and the second in a deposit (litoteca) dedicated to the rocks storage. Thus, the members of the public are only occasionally exposed to the natural gamma radiation there. Additionally, the Ed values are much lower than the recommended limit of 20 mSv/year for occupationally exposed individuals.  相似文献   

Recent trends in vegetation dynamics in the South America and their relationship to rainfall   总被引：2，自引：2，他引：0  

H. A. Barbosa  T. V. Lakshmi Kumar  L. R. M. Silva 《Natural Hazards》2015,77(2):883-899

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What is wrong with post-fire soil erosion modelling? A meta-analysis on current approaches,research gaps,and future directions     

A.R. Lopes  A. Girona-García  S. Corticeiro  R. Martins  J.J. Keizer  D.C.S. Vieira 《地球表面变化过程与地形》2021,46(1):205-219

In the near future, a higher occurrence of wildfires is expected due to climate change, carrying social, environmental, and economic implications. Such impacts are often associated with an increase of post-fire hydrological and erosive responses, which are difficult to predict. Soil erosion models have been proven to be a valuable tool in the decision-making process, from emergency response to long-term planning, however, they were not designed for post-fire conditions, so need to be adapted to include fire-induced changes. In recent years, there have been an increasing number of studies testing different models and adaptations for the prediction of post-fire soil erosion. However, many of these adaptations are being applied without field validation or model performance assessment. Therefore, this study aims to describe the scientific advances in the last 20 years in post-fire soil erosion modelling research and evaluate model adaptations to burned areas that aim to include: (i) fire-induced changes in soil and ground cover; (ii) fire-induced changes in infiltration; (iii) burn severity; and (iv) mitigation measures in their predictions. This study also discusses the strengths and weaknesses of these approaches, suggests potential improvements, and identifies directions for future research. Results show that studies are not homogeneously distributed worldwide, according to the model type used or by region most affected by wildfire. During calibration, 73% of cases involved model adaptation to burned conditions, and only 21% attempted to accommodate new processes. Burn severity was addressed in 75% of cases, whilst mitigation measures were simulated in 27%. Additionally, only a minor percentage of model predictions were validated with independent field data (17%) or assessed for uncertainties (13%). Therefore, further efforts are required in the adaptation of erosion models to burned conditions, to be widely used for post-fire management decisions. © 2020 John Wiley & Sons, Ltd.  相似文献   

Daily streamflow forecasting using a wavelet transform and artificial neural network hybrid models     

Celso Augusto Guimarães Santos  Gustavo Barbosa Lima da Silva 《水文科学杂志》2013,58(2):312-324

Abstract

New wavelet and artificial neural network (WA) hybrid models are proposed for daily streamflow forecasting at 1, 3, 5 and 7 days ahead, based on the low-frequency components of the original signal (approximations). The results show that the proposed hybrid models give significantly better results than the classical artificial neural network (ANN) model for all tested situations. For short-term (1-day ahead) forecasts, information on higher-frequency signal components was essential to ensure good model performance. However, for forecasting more days ahead, lower-frequency components are needed as input to the proposed hybrid models. The WA models also proved to be effective for eliminating the lags often seen in daily streamflow forecasts obtained by classical ANN models. 

Editor D. Koutsoyiannis; Associate editor L. See

Citation Santos, C.A.G. and Silva, G.B.L., 2013. Daily streamflow forecasting using a wavelet transform and artificial neural network hybrid models. Hydrological Sciences Journal, 59 (2), 312–324.  相似文献   

Geochemical tracers of northern Portuguese estuarine sediments on the shelf     

M. F. Araújo  J. -M. Jouanneau  P. Valrio  T. Barbosa  A. Gouveia  O. Weber  A. Oliveira  A. Rodrigues  J. M. A. Dias 《Progress in Oceanography》2002,52(2-4)

The northern Portuguese coastal zone is drained by large Iberian rivers, along which there is intensive industrial, agricultural and urban activity. Offshore of the two main river basins of the Douro and Minho, two fine-grained sedimentary formations can be characterised. A geochemical study of this sediment cover has been performed focussing in particular on the fine deposits and the adjacent estuaries. The chemical composition of superficial sediments collected from the northern Portuguese shelf and from the river basins of the Minho and Douro rivers was determined for major, minor and trace elements; the rare earth elements (REE) composition was also determined in selected samples. Statistical analyses of these data for the shelf sediments allow us to identify elements with similar behaviours and the different sediment types along the shelf, and to evaluate of their origins. Downcore profiles of the chemical composition of the fine sediments reveal no evidence for changes induced by recent human activities. To assess the influence of the rivers on the fine sedimentary formations, the elemental distribution patterns of selected sediments have been compared with the estuarine sediments. Lithogenic elements composition normalised to Al and the shale normalised REE distributions showed there are similarities between the Douro River sediments and the sediment composition of the Douro and Galicia mud patches. However, the Galicia mud field showed no relationship in its chemical composition to sediments derived from the Minho River. Nor was any evidence for heavy metal contamination originating from the Douro estuary detected in anthropogenic element/Al ratios in the shelf sediments. This may be because of processes associated with resuspension, complexation and bioturbation that occur during sediment transport and deposition. Nevertheless, the Douro River seems to be the main continental source of fine sediments being deposited on the northern Portuguese shelf.  相似文献   

Digital complex correlator for a C-band polarimetry survey     

Miguel Bergano  Francisco Fernandes  Luís Cupido  Domingos Barbosa  Rui Fonseca  Ivan Ferreira  Bruce Grossan  George Smoot 《Experimental Astronomy》2011,30(1):23-37

The international Galactic Emission Mapping project aims to map and characterize the polarization field of the Milky Way. In Portugal it will map the sky polarized emission of the Northern Hemisphere in C-band and provide templates for map calibration and foreground control of microwave space data to be provided by ESA Planck Surveyor mission and later missions. The receiver system is equipped with a novel receiver with a full digital back-end using a low-cost Field Programmable Gate Array without compromising its performance relation. This new digital backend comprises a base-band complex cross-correlator outputting the four Stokes parameters of the incoming polarized radiation. In this document we describe the design and implementation of the complex correlator using the FPGA and the dedicated digitizers at each receiver arm, detailing the method applied at the several algorithm stages. This correlator is suitable for large sky area polarization continuum surveys.  相似文献   

Material screening and selection for XENON100     

E. Aprile  K. Arisaka  F. Arneodo  A. Askin  L. Baudis  A. Behrens  K. Bokeloh  E. Brown  J.M.R. Cardoso  B. Choi  D. Cline  S. Fattori  A.D. Ferella  K.L. Giboni  A. Kish  C.W. Lam  J. Lamblin  R.F. Lang  K.E. Lim  J.A.M. Lopes  T. Marrodán Undagoitia  Y. Mei  A.J. Melgarejo Fernandez  K. Ni  U. Oberlack  S.E.A. Orrigo  E. Pantic  G. Plante  A.C.C. Ribeiro  R. Santorelli  J.M.F. dos Santos  M. Schumann  P. Shagin  A. Teymourian  D. Thers  E. Tziaferi  H. Wang  C. Weinheimer  M. LaubensteinS. Nisi 《Astroparticle Physics》2011,35(2):43-49

Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This dark matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples. Detailed tables with the radioactive contaminations of all screened samples are presented, together with the implications for XENON100.  相似文献   

Limit Equilibrium Analyses for Internal Design of Geosynthetic Reinforced Slopes: Influence of Potential Failure Surface and Strength Distribution     

Castorina Silva Vieira  Maria de Lurdes Lopes  Laura M. Caldeira 《Geotechnical and Geological Engineering》2013,31(4):1123-1135

The paper presents results from a computer code, based on limit equilibrium analyses, able to quantify earth pressure coefficients for the internal design of geosynthetic reinforced soil structures and identify the potential failure surfaces. Failure mechanisms assuming bilinear or logarithmic spiral failure surfaces are considered. The influence of the potential failure surface and geosynthetic strength distribution on the earth pressure coefficient is analysed. Required reinforcement tensile strengths calculated by the developed program are compared with values published in the literature. To further evaluate the capabilities of limit equilibrium analyses, the numerical modelling of a geosynthetic reinforced steep slope, designed at ultimate limit state conditions (FS = 1), is also presented. Good agreement was achieved between the potential failure surfaces predicted by limit equilibrium analyses and those obtained with numerical modelling.  相似文献   

Electrochemical Treatment of Olive Processing Wastewater Using a Boron‐Doped Diamond Anode          下载免费PDF全文

José Barbosa  Annabel Fernandes  Lurdes Ciríaco  Ana Lopes  Maria José Pacheco 《洁净——土壤、空气、水》2016,44(9):1242-1249

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