Forest fire danger projections in the Mediterranean using ENSEMBLES regional climate change scenarios   总被引：1，自引：1，他引：0  

J. Bedia  S. Herrera  A. Camia  J. M. Moreno  J. M. Gutiérrez 《Climatic change》2014,122(1-2):185-199

We present future fire danger scenarios for the countries bordering the Mediterranean areas of Europe and north Africa building on a multi-model ensemble of state-of-the-art regional climate projections from the EU-funded project ENSEMBLES. Fire danger is estimated using the Canadian Forest Fire Weather Index (FWI) System and a related set of indices. To overcome some of the limitations of ENSEMBLES data for their application on the FWI System—recently highlighted in a previous study by Herrera et al. (Clim Chang 118:827–840, 2013)—we used an optimal proxy variable combination. A robust assessment of future fire danger projections is undertaken by disentangling the climate change signal from the uncertainty derived from the multi-model ensemble, unveiling a positive signal of fire danger potential over large areas of the Mediterranean. The increase in the fire danger signal is accentuated towards the latest part of the transient period, thus pointing to an elevated fire potential in the region with time. The fire-climate links under present and future conditions are further discussed building upon observed climate data and burned area records along a representative climatic gradient within the study region.  相似文献   

Two Tales of a City: detecting socio-economic disadvantage in an ‘advantaged’ Australian urban centre     

Xavier Goldie  Isabel Kakuk  Gemma Wood 《The Australian geographer》2014,45(4):521-540

Understanding the distribution of socio-economic status (SES) within and between communities of varying spatial scales is vital for equitable and effective resource delivery and policy development. In Australia, the Socio-economic Indexes for Areas (SEIFA) have been used extensively for these purposes, in both research and government service delivery. As area-based averages, however, their use in these areas is potentially confounded by the ecological fallacy and the modifiable areal unit problem (MAUP), statistical issues which have widespread implications for the use of spatial data. The Socio-economic Index for Individuals (SEIFI) is an individual-based index developed by the ABS to quantify SES at an individual level for 15–64 year-old Australians. Previous work investigated the potential disparities between these area- and individual-level indices, showing that considerable disparities exist, particularly in the Australian Capital Territory (ACT). Using spatial autocorrelation and pair-wise proportion analyses, we show that there was considerable diversity in individual-level SES at a very fine level of geography in 2006, a unique pattern in Australia. We also show that the SES ranking of areas within the ACT is, in many instances, not indicative of the proportions of individuals living within that area experiencing high levels of relative socio-economic disadvantage. We show that between 65–95 per cent of the ACT's disadvantaged population are masked within areas ranked as advantaged, depending on the index and level of spatial aggregation. Our results suggest that the use of SEIFA as a proxy for individual level disadvantage is highly problematic at both a theoretical and practical level, and necessitates further development of an individual- or household-level index as part of the regular suite of socio-economic indices produced by the ABS.  相似文献   

Estimation of nearshore groundwater discharge and its potential effects on a fringing coral reef     

Blanco AC  Watanabe A  Nadaoka K  Motooka S  Herrera EC  Yamamoto T 《Marine pollution bulletin》2011,62(4):770-785

Radon (²²²Rn) measurements were conducted in Shiraho Reef (Okinawa, Japan) to investigate nearshore submarine groundwater discharge (SGD_nearshore) dynamics. Estimated average groundwater flux was 2-3 cm/h (maximum 7-8 cm/h). End-member radon concentration and gas transfer coefficient were identified as major factors influencing flux estimation accuracy. For the 7-km long reef, SGD_nearshore was 0.39-0.58 m³/s, less than 30% of Todoroki River’s baseflow discharge. SGD_nearshore was spatially and temporally variable, reflecting the strong influence of subsurface geology, tidal pumping, groundwater recharge, and hydraulic gradient. SGD_nearshore elevated nearshore nitrate concentrations (0.8-2.2 mg/l) to half of Todoroki River’s baseflow -N (2-4 mg/L). This increased nearshore Chl-a from 0.5-2 μg/l compared to the typically low Chl-a (<0.1-0.4 μg/l) in the moat. Diatoms and cyanobacteria concentrations exhibited an increasing trend. However, the percentage contributions of diatoms and cyanobacteria significantly decreased and increased, respectively. SGD may significantly induce the proliferation of cyanobacteria in nearshore reef areas.  相似文献   

Location of buried plastic pipes using multi-agent support based on GPR images     

David Ayala-CabreraManuel Herrera  Joaquín IzquierdoRafael Pérez-García 《Journal of Applied Geophysics》2011,75(4):679-686

This work focuses on the generation of tools to aid inspection and identify buried plastic pipes in water supply systems (WSS). In our study we use ground penetrating system (GPR) images as a non-destructive method of obtaining information without altering the system conditions and the environmental characteristics. A viability study for extracting features, and an approach to the above-mentioned application based on multi-agent systems are addressed in this paper. Firstly, we use intensive matrix manipulation of the GPR output for preprocessing the images. As a result, two matrices are produced that classify initial data based on the original radargram of the wave amplitude parameter. Then the plastic pipe characteristics that offer an enhanced likelihood of location are defined. This procedure is evaluated through two case-studies. One study corresponds to a simple case (one pipe) and the other corresponds to various pipes (made of different materials). Both cases were developed under controlled laboratory conditions. The obtained results are promising, and we show that automatic plastic pipe location has been achieved. The main contributions of the procedures proposed in this work are: firstly, highly skilled GPR prospection operators become unnecessary for plastic pipe location using GPR images; and secondly, we have opened a route to further classification that makes use of other methodologies.  相似文献   

Analysis with C- and X-band satellite SAR data of the Portalet landslide area   总被引：1，自引：0，他引：1  

Gerardo Herrera  Davide Notti  Juan Carlos Garc��a-Davalillo  Oscar Mora  Geraint Cooksley  M��nica S��nchez  Alain Arnaud  Michele Crosetto 《Landslides》2011,8(2):195-206

This paper describes the use of the Stable Point Network technique, a Persistent Scatterer Interferometry SAR technique, for the analysis of the Portalet landslide area (Central Pyrenees, Spain). For this purpose, different SAR datasets acquired by ERS-1, ERS-2, ENVISAT and TerraSAR-X satellites have been analysed. The use of different SAR images acquired by satellite radar sensors operating at different microwave lengths has allowed for a comparative assessment and illustration of the advantages and disadvantages of these satellites for landslide detection and monitoring. In the introduction, differential interferometry and the study area are briefly described. Then the specifics of the SPN processing and the results of the different datasets are described and compared. In Analysis of the results: the Portalet landslide area, the Portalet landslide area is introduced and the radar displacement measurements are analysed with available geo-information data. Additionally, X-band measurements are compared with those gathered by a ground-based SAR for a previous project. Finally, the most relevant conclusions of this work are discussed.  相似文献   

Imaging the recent sediment dynamics of the Galicia Bank region (Atlantic,NW Iberian Peninsula)     

Gemma Ercilla  David Casas  Juan T. Vázquez  Jorge Iglesias  Luís Somoza  Carmen Juan  Teresa Medialdea  Ricardo León  Ferran Estrada  Soledad García-Gil  Marcel.lí Farran  Fernando Bohoyo  Margarita García  Adolfo Maestro  ERGAP Project  Cruise Teams 《Marine Geophysical Researches》2011,32(1-2):99

Multibeam bathymetry, high resolution multi-channel, and very high resolution single-channel (3.5 kHz) seismic records were used to depict the complex geomorphology that defines the Galicia Bank region (Atlantic, NW Iberian Peninsula). This region (≈620–5,000 m water depth) is characterized by a great variety of features: structural features (scarps, highs, valleys, fold bulges), fluid dynamics-related features (structural undulations and collapse craters), mass-movement features (gullies, channels, mass-flow deposits, slope-lobe complexes, and mass-transport deposits), bottom-current features (moats, furrows, abraded surface, sediment waves, and drifts), (hemi)pelagic features, mixed features (abraded surfaces associated to mixed sediments) and bioconstructions. These features represent architectural elements of four sedimentary systems: slope apron, contouritic, current-controlled (hemi)pelagic, and (hemi)pelagic. These systems are a reflection of different sedimentary processes: downslope (mass transport, mass flows, turbidity flows), alongslope (bottom currents of Mediterranean Outflow Water, Labrador Sea Water, North Atlantic Deep Water, and Lower Deep Water), vertical settling, and the interplay between them. The architectural and sediment dynamic complexities, for their part, are conditioned by the morphostructural complexity of the region, whose structures (exposed scarps and highs) favor multiple submarine sediment sources, affect the type and evolution of the mass-movement processes, and interact with different water masses. This region and similar sedimentary environments far from the continental sediment sources, as seamounts, are ideal zones for carrying out submarine source-to-sink studies, and can represent areas subject to hazards, both geologic and oceanographic in origin.  相似文献   

Impact of pulsed Atlantic water inflow into the Alboran Basin at the time of the Zanclean flooding     

Ferran Estrada  Gemma Ercilla  Christian Gorini  Bel��n Alonso  Juan Tom��s V��zquez  Daniel Garc��a-Castellanos  Carmen Juan  Andr��s Maldonado  Abdellah Ammar  Mohammed Elabbassi 《Geo-Marine Letters》2011,31(5-6):361-376

The study of more than 500 single- and multichannel seismic records enabled the generation of a detailed palaeo-bathymetric map of the Messinian surface over most of the Alboran Basin, Western Mediterranean. This regional surface is characterized by several erosional features (channels, terraces and canyons) and topographic highs (structural, volcanic and diapiric in origin). The most prominent feature is the incised Zanclean Channel crossing the entire basin, its entrenchment having been associated with the opening of the Strait of Gibraltar and subsequent inflow of Atlantic waters. The incision depth of the channel is variable, suggesting local variations in the erosive capacity of the Atlantic inflow, conditioned mainly by the regional basin topography and the local presence of topographic highs. Adjacent to this channel along the Spanish and Moroccan margins, and near the Strait of Gibraltar, several submarine terraces developed at different depths suggest a pulsed flooding of the Alboran Basin. There could have been two major inflow phases of Atlantic water, one shortly before and another during the Zanclean flooding, the latter accompanied by periods of relative sea-level stillstands that enabled terrace development. Alternatively, these features were all generated during the main flooding evident and subsequent pulsed infilling of the basin.  相似文献   

A late Holocene record of arid events from the Cuzco region,Peru     

Alex Chepstow‐Lusty  Michael R. Frogley  Brian S. Bauer  Mark. B. Bush  Alfredo Tupayachi Herrera 《第四纪科学杂志》2003,18(6):491-502

The small recently infilled lake basin of Marcacocha (13°13′S, 72°12′W, 3355 m) in the Cuzco region of Peru has a morphology and location that renders it extremely sensitive to environmental change. A record of vegetation, human impact and climatic change during the past 4200 yr has been obtained from a highly organic core taken from the centre of the basin. Sustained arid episodes that affected the Peruvian Andes may be detectable using the proxy indicator of sedge (Cyperaceae) pollen abundances. As the lake‐level was lowered during sustained drier conditions, the local catchment was colonised by Cyperaceae, whereas during lake floods, they retreated or were submerged and pollen production was correspondingly reduced. Drier episodes during prehistoric times occurred around 900 bc , 500 bc , ad 100 and ad 550, with a longer dry episode occurring from ad 900 to 1800. Evidence from the independently derived Quelccaya ice‐core record and the archaeological chronology for the Cuzco region appears to support the climatic inferences derived from the sedge data. Many of these aridity episodes appear to correspond with important cultural changes in the Cuzco region and elsewhere in the Central Andes. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Non-Spherical Sources of Strong Gravitational Fields Out of Hydrostatic Equilibrium     

L. Herrera  A. Di Prisco  J. Martínez 《Astrophysics and Space Science》2001,277(3):447-459

We describe the departure from equilibrium of matter distributions representing sources for a class of Weyl metric. It is shown that, for extremely high gravitational fields, slight deviations from spherical symmetry may weaken its tendency to a catastrophic collapse. For critical values of surface gravitational potential, in contrast with the exactly spherically symmetric case, the speed of entering the collapse regime decreases substantially, at least for specific cases. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Shear-free and homology conditions for self-gravitating dissipative fluids     

L. Herrera  N. O. Santos 《Monthly notices of the Royal Astronomical Society》2003,343(4):1207-1212

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