Physically based shallow translational landslide susceptibility analysis in Tibo catchment,NW of Portugal     

Manuel Teixeira  Carlos Bateira  Fernando Marques  Bianca Vieira 《Landslides》2015,12(3):455-468

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Exploring the time geography of public transport networks with the gtfs2gps package     

Pereira  Rafael H. M.  Andrade  Pedro R.  Vieira  João Pedro Bazzo 《Journal of Geographical Systems》2023,25(3):453-466

Journal of Geographical Systems - The creation of the General Transit Feed Specification (GTFS) in the mid-2000s provided a new data format for cities to organize and share digital information on...  相似文献   

Evaluation of water resources in a high-mountain basin in <Emphasis Type="Italic">Serra da Estrela</Emphasis>, Central Portugal,using a semi-distributed hydrological model     

J. Espinha Marques  J. Samper  B. Pisani  D. Alvares  J. M. Carvalho  H. I. Chaminé  J. M. Marques  G. T. Vieira  C. Mora  F. Sodré Borges 《Environmental Earth Sciences》2011,62(6):1219-1234

High-mountain basins provide a source of valuable water resources. This paper presents hydrological models for the evaluation of water resources in the high-mountain Zêzere river basin in Serra da Estrela, Central Portugal. Models are solved with VISUAL BALAN v2.0, a code which performs daily water balances in the root zone, the unsaturated zone and the aquifer and requires a small number of parameters. A lumped hydrological model fails to fit measured stream flows. Its limitations are overcome by considering the dependence of the temperature and precipitation data with elevation and the spatial variability in hydrogeomorphological variables with nine sub-basins of uniform parameters. Model parameters are calibrated by fitting stream flow measurements in the Zêzere river. Computed stream flows are highly sensitive to soil thickness, whereas computed groundwater recharge is most sensitive to the interflow and percolation recession coefficients. Interflow is the main component of total runoff, ranging from 41 to 55% of annual precipitation. High interflows are favored by the steep relief of the basin, by the presence of a high permeability soil overlying the fractured low permeability granitic bedrock and by the extensive subhorizontal fracturing at shallow depths. Mean annual groundwater recharge ranges from 11 to 15% of annual precipitation. It has a significant uncertainty due to uncertainties in soil parameters. This methodology proves to be useful to handle the research difficulties regarding a complex mountain basin in a context of data scarcity.  相似文献   

Multi-Scale Analysis of the Geomagnetic Symmetric Index (sym)     

Vieira  L.E.A.  Gonzalez  W.D.  Echer  E.  Guarnieri  F.L.  Prestes  A.  Gonzalez  A.L.C.  Santos  J.C.  Dal Lago  A.  Schuch  N.J. 《Solar physics》2003,217(2):383-394

In this work we present a methodology to estimate the geomagnetic symmetric index (Sym) based on the wavelet analysis of the time series of the H component of the geomagnetic field measured at mid-latitude stations localized at Kakioka (KAK), Honolulu (HON), Hermanus (HER) and San Juan (SJG). A case study of the intense geomagnetic storm of 17–22 February 1999, caused by intense southward magnetic fields just behind an interplanetary shock driven by a magnetic cloud, is shown as an example of the procedure of derivation of the symmetric index and the capabilities of this analysis to improve the study of the coupling of the solar wind and the Earth's magnetosphere. Other examples are shown in order to demonstrate the applicability of the methodology to different magnetospheric conditions. It is shown that the long period variations of the symmetric index are linearly correlated to variations at the same periods of the H component of the geomagnetic field and that the contribution of short period variations to the symmetric index are biased by localized current systems such as the partial ring current and the field aligned currents.  相似文献   

Comparison Between Halo cme Expansion Speeds Observed on the Sun,the Related Shock Transit Speeds to Earth and Corresponding Ejecta Speeds at 1 au   总被引：1，自引：0，他引：1  

Dal Lago  A.  Vieira  L.E.A.  Echer  E.  Gonzalez  W.D.  de Gonzalez  A.L.C.  Guarnieri  F.L.  Schuch  N.J.  Schwenn  R. 《Solar physics》2004,222(2):323-328

We have compared characteristics of 38 halo coronal mass ejections observed on the Sun by the Large Angle and Spectrometric Coronagraph onboard SOHO with their corresponding counterparts observed near Earth by the magnetic field and plasma instruments onboard the ACE, WIND and SOHO satellites, in the period from January 1997 to April 2001. We only have selected events that have some associated interplanetary ejecta structure at 1 AU and we have compared the lateral expansion speeds of these halo CMEs and the corresponding ejecta speeds near Earth. We found that there is a high correlation between these two speeds. The results are very similar to the study done by Lindsay et al. (1999) using observations made by Solwind and SMM coronagraphs, and Helios-1 and PVO plasma and interplanetary field data from the period of 1979 to 1988. Also, we reviewed the relation between the CME-related shock transit speed to Earth and the ejecta speeds near Earth. This kind of relation is very important to estimate ejecta speeds of events for which no interplanetary observations are available.  相似文献   

Performance-based design optimization of embankments resting on soft soil improved with T-shaped and conventional DCM columns     

Phutthananon  Chana  Jongpradist  Pornkasem  Jongpradist  Pattaramon  Dias  Daniel  Jamsawang  Pitthaya  Bergado  Dennes T. 《Acta Geotechnica》2021,16(10):3301-3326

Acta Geotechnica - This paper presents a parametric study of the optimization design for T-shaped deep cement mixing (TDM) and conventional deep cement mixing (DCM) columns improved soft soil for...  相似文献   

From the plutonic root to the volcanic roof of a continental magmatic arc: a review of the Neoproterozoic Araçuaí orogen,southeastern Brazil     

Gonçalves  Leonardo  Alkmim  Fernando F.  Pedrosa-Soares  Antônio  Gonçalves  Cristiane C.  Vieira  Valter 《International Journal of Earth Sciences》2018,107(1):337-358

International Journal of Earth Sciences - The Araçuaí-West Congo orogen (AWCO) is one of the various components of the Brasiliano/Pan-African orogenic network generated during the...  相似文献   

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   

Distribution of heavy metals and pollution pathways in a shallow marine shelf: assessment for a future management     

F. Ruiz  M. L. González-Regalado  J. M. Muñoz  M. Abad  A. Toscano  M. I. Prudencio  M. I. Dias 《International Journal of Environmental Science and Technology》2014,11(5):1249-1258

The spatial distribution and geoaccumulation indices of four heavy metals were investigated in very shallow marine sediments of southwestern Spain. Surface sediments were collected from 43 sites with water depth ranging from 3 to 20 m. High to very high pollution levels (I _geo > 4 for zinc, lead and copper) were detected near the end of the Huelva bank, whereas chromium shows a more hazardous distribution in the southwestern Spanish littoral. Low to moderate heavy metal contents (mainly zinc and lead) were also observed in other two areas at different water depths (Isla Cristina-Piedras River: 10–18 m water depth; Mazagón–Matalascañas: <10 m water depth), whereas unpolluted to moderately polluted sediments were detected in the very shallow zones (<8 m water depth) located between the mouths of the Guadiana and the Piedras Rivers. A regional scenario indicates a strong pollution of the adjacent marine areas by polluted inputs derived from the Tinto–Odiel rivers, with a partial transport of heavy metals by W–E littoral currents even 40 km eastward. The Guadiana River is an additional source of zinc–lead contamination near the Spanish–Portuguese border, mainly at water depths up to 10 m. All these rivers are affected by acid mine drainage processes, derived from millennial mining activities. This pollution affects the sediment quality even 40 km eastward.  相似文献   

What causes the spread of model projections of ocean dynamic sea-level change in response to greenhouse gas forcing?     

Couldrey  Matthew P.  Gregory  Jonathan M.  Boeira Dias  Fabio  Dobrohotoff  Peter  Domingues  Catia M.  Garuba  Oluwayemi  Griffies  Stephen M.  Haak  Helmuth  Hu  Aixue  Ishii  Masayoshi  Jungclaus  Johann  Köhl  Armin  Marsland  Simon J.  Ojha  Sayantani  Saenko  Oleg A.  Savita  Abhishek  Shao  Andrew  Stammer  Detlef  Suzuki  Tatsuo  Todd  Alexander  Zanna  Laure 《Climate Dynamics》2021,56(1-2):155-187

Sea levels of different atmosphere–ocean general circulation models (AOGCMs) respond to climate change forcing in different ways, representing a crucial uncertainty in climate change research. We isolate the role of the ocean dynamics in setting the spatial pattern of dynamic sea-level (ζ) change by forcing several AOGCMs with prescribed identical heat, momentum (wind) and freshwater flux perturbations. This method produces a ζ projection spread comparable in magnitude to the spread that results from greenhouse gas forcing, indicating that the differences in ocean model formulation are the cause, rather than diversity in surface flux change. The heat flux change drives most of the global pattern of ζ change, while the momentum and water flux changes cause locally confined features. North Atlantic heat uptake causes large temperature and salinity driven density changes, altering local ocean transport and ζ. The spread between AOGCMs here is caused largely by differences in their regional transport adjustment, which redistributes heat that was already in the ocean prior to perturbation. The geographic details of the ζ change in the North Atlantic are diverse across models, but the underlying dynamic change is similar. In contrast, the heat absorbed by the Southern Ocean does not strongly alter the vertically coherent circulation. The Arctic ζ change is dissimilar across models, owing to differences in passive heat uptake and circulation change. Only the Arctic is strongly affected by nonlinear interactions between the three air-sea flux changes, and these are model specific.

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