Decades of Drought, Years of Hunger: Archival Investigations of Multiple Year Droughts in Late Colonial Chihuahua     

Georgina H. Endfield  Isabel Fern´ndez Tejedo 《Climatic change》2006,75(4):391-419

Unusually severe or prolonged drought ranks among the most devastating and calamitous of all extreme climate events, contributing to wildfires, crop failure, livestock death, food shortages and famine. The response of human activities and the natural environment to such historical weather perturbations provides a guide to where the most critical sensitivities to future climate changes may lie (McCarthy et al., 2001, ‘Climatic change 2001: Impact adaptation, and vulnerability’, from 3rd Assesment Report of IPCC). The reconstruction of regional climatic histories and investigations of the impacts of – and social response to – extreme droughts in history are thus of crucial significance if we are to understand and anticipate the potential repercussions of future events (Wigley, 1985, Nature 316, 106–107; Grove and Conterio, 1995, Clim. Change 30, 223). Chihuahua, in the arid Northwest of Mexico, is one of the most seriously and frequently drought affected regions of the country (Garcia, 2000, available at www.sequia.edu.mx/proyectos/vulnera.html). Prolonged drought in the 1930s, 1950s and 1990s contributed to water scarcity, harvest failure, illness, livestock disease, abandonment and water conflict and served to highlight the particular vulnerability of agrarian society in this region to climatic variability (Sandoval, 2003, Ingeneria Hidraulica en Mexico 18(2), 133–155). Recent investigations using tree ring analysis have identified several phases of such prolonged drought over the last seven centuries. In this paper we use archival documents to investigate the impacts of such periods in late colonial Chihuahua and to explore how society in the region responded to and coped with them.  相似文献   

Long-term neutralisation potential of red mud bauxite with brine amendment for the neutralisation of acidic mine tailings     

M. Paradis  J. Duchesne  A. Lamontagne  D. Isabel 《Applied Geochemistry》2007

Acid mine drainage is an environmental problem produced when sulphide in mine tailings dams comes in contact with O₂, bacteria and water. Oxidation occurs and a succession of reactions is responsible for producing acid and metals in the environment. One solution proposed is to use red mud bauxite (RMB) that is very alkaline to neutralise acidic tailings. Previous experiments showed that RMB has a good neutralisation capacity for a short time, but the long-term neutralisation potential is uncertain. So brine was added to RMB to verify if it can improve long-term alkalinity retention of RMB. Some authors have presented results where seawater or other natural or artificial Ca- and Mg-rich brines were used with RMB to convert the basicity (mainly NaOH) and other soluble alkalinity into low solubility hydroxide, carbonate and hydroxycarbonate minerals. Results showed that neutral pH conditions were maintained over the entire test for RMB and a mixture of RMB with brine. Addition of brine to RMB slightly lowered the pH compared to RMB alone. RMB alone lost a lot of dissolved alkalinity at the beginning of the test. Most of the alkalinity was lost in water after a few flushes for RMB samples. The addition of brine helped to keep neutralisation potential over more cycles of leaching.  相似文献   

ISPRS Commission Iii Symposium: Photogrammetric Computer Vision 2006     

Isabel  Sargent Sarah  Smith-Voysey 《The Photogrammetric Record》2007,22(117):88-90

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Morphometrical analysis of torrential flows-prone catchments in tropical and mountainous terrain of the Colombian Andes by machine learning techniques     

Arango  María Isabel  Aristizábal  Edier  Gómez  Federico 《Natural Hazards》2021,105(1):983-1012

Natural Hazards - Assessment of susceptibility to torrential flows at the catchment scale is a necessary step for prioritising zones that can be identified by hazard and risk maps. In the Andean...  相似文献   

Prediction of California Bearing Ratio from Index Properties of Soils Using Parametric and Non-parametric Models     

Isabel González Farias  William Araujo  Gaby Ruiz 《Geotechnical and Geological Engineering》2018,36(6):3485-3498

This work proposes a methodology to obtain from the soils properties the best prediction model for the California bearing ratio index. The methodology proposes three different prediction techniques: (1) the multiple linear regression, a classical parametric technique; and two non-parametric techniques: (2) the local polynomial regression (LPR) and (3) the radial basis network. The LPR is a known statistical method, but in the geotechnical engineering field is not in common use. Besides, although several research works have been published in this field, they do not include a robust procedure for making good comparison between different models. Here, a cross validation method is proposed with this aim. A data set of 96 samples from Peruvian soils is used to illustrate the methodology. To validate the proposed methodology, a data set from the literature is also analyzed.  相似文献   

Plant–water relations of intertidal and subtidal seagrasses          下载免费PDF全文

Jose M. Sandoval‐Gil  Isabel Barrote  João Silva  Irene Olivé  Monya M. Costa  Juan M. Ruiz  Lázaro Marín‐Guirao  Jose L. Sánchez‐Lizaso  Rui Santos 《Marine Ecology》2015,36(4):1294-1310

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New Hamiltonian expansions adapted to the Trojan problem     

Rocío?Isabel?PáezEmail author  Ugo?Locatelli  Christos?Efthymiopoulos 《Celestial Mechanics and Dynamical Astronomy》2016,126(4):519-541

A number of studies, referring to the observed Trojan asteroids of various planets in our Solar System, or to hypothetical Trojan bodies in extrasolar planetary systems, have emphasized the importance of so-called secondary resonances in the problem of the long term stability of Trojan motions. Such resonances describe commensurabilities between the fast, synodic, and secular frequency of the Trojan body, and, possibly, additional slow frequencies produced by more than one perturbing bodies. The presence of secondary resonances sculpts the dynamical structure of the phase space. Hence, identifying their location is a relevant task for theoretical studies. In the present paper we combine the methods introduced in two recent papers (Páez and Efthymiopoulos in Celest Mech Dyn Astron 121(2):139, 2015; Páez and Locatelli in MNRAS 453(2):2177, 2015) in order to analytically predict the location of secondary resonances in the Trojan problem. In Páez and Efthymiopoulos (2015), the motion of a Trojan body was studied in the context of the planar Elliptic Restricted Three Body or the planar Restricted Multi-Planet Problem. It was shown that the Hamiltonian admits a generic decomposition \(H=H_b+H_{sec}\). The term \(H_b\), called the basic Hamiltonian, is a model of two degrees of freedom characterizing the short-period and synodic motions of a Trojan body. Also, it yields a constant ‘proper eccentricity’ allowing to define a third secular frequency connected to the body’s perihelion precession. \(H_{sec}\) contains all remaining secular perturbations due to the primary or to additional perturbing bodies. Here, we first investigate up to what extent the decomposition \(H=H_b+H_{sec}\) provides a meaningful model. To this end, we produce numerical examples of surfaces of section under \(H_b\) and compare with those of the full model. We also discuss how secular perturbations alter the dynamics under \(H_b\). Secondly, we explore the normal form approach introduced in Páez and Locatelli (2015) in order to find an ‘averaged over the fast angle’ model derived from \(H_b\), circumventing the problem of the series’ limited convergence due to the collision singularity at the 1:1 MMR. Finally, using this averaged model, we compute semi-analytically the position of the most important secondary resonances and compare the results with those found by numerical stability maps in specific examples. We find a very good agreement between semi-analytical and numerical results in a domain whose border coincides with the transition to large-scale chaotic Trojan motions.  相似文献   

Finding meaningful participation in volunteer geographic information and citizen science: a case comparison in environmental application     

Mu-Ning W. Brandeis  Maria Isabel Carrera Zamanillo 《制图学和地理信息科学》2017,44(6):539-550

ABSTRACT

Volunteer geographic information (VGI) and citizen science (CS) have been used as a way to promote a form of democratization of knowledge. Crowdsourcing facilitates the massive collection of data through nonexpert volunteers. This study compares 57 VGI and CS projects through a cross-case comparison method to explore the level of involvement of participants, based on three main analytic dimensions (project rationale, actor interaction, and data flow) and 12 sub-variables. The primary goal of this research is to analyze the purpose and the role of technology in VGI and CS projects, using three matrices to explore emerging trade-offs. Finally, we synthesized the workflow of VGI and CS project and compared based on project purposes. At the end of this study, five main purposes were found among the selected projects, uncovering that data collection is the most common purpose. A general workflow can be conceptualized, but detail implementation will involve various trade-offs, especially between local involvement and large-area expert-oriented protocol implementations. By exploring diverse relationships among selected variables of analysis in VGI and CS projects, this study pretends to build a foundation for larger, global meta-analysis that can bring some transparency in the epistemic interactions between experts and nonexperts.  相似文献   

Inorganic ions and trace metals bulk deposition at an Atlantic Coastal European region     

Jorge Moreda-Piñeiro  Elia Alonso-Rodríguez  Isabel Turnes-Carou  Carmen Moscoso-Pérez  Gustavo Blanco-Heras  Loreto Gómez Tellado  Purificación López-Mahía  Soledad Muniategui-Lorenzo  Darío Prada-Rodríguez 《Journal of Atmospheric Chemistry》2017,74(1):1-21

The inorganic chemical composition (major ions and trace metals) of bulk deposition samples collected monthly with bulk collectors at seven Atlantic Coastal European cities (Galicia, Northwest of Spain) during wet season (September 2011 to March 2012) has been assessed and compared. Trace metals (Al, As, Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn) were analysed in soluble fraction and non-soluble fraction (after acid extraction) of the bulk deposition by inductively coupled plasma-mass spectrometry. Major inorganic ions (Cl^?, NO₃ ^?, SO₄ ^2?, Na⁺, K⁺, Ca²⁺, Mg²⁺ and NH₄ ⁺) were analysed in the soluble fraction of the bulk deposition by capillary zone electrophoresis. Univariate analysis (ANOVA and Multiple Range Test) according to the location of each sampling site was performed. Results also suggest a great influence of cleaner Atlantic air masses. After partition coefficients and enrichment factor estimation, similar sources could be assigned for the ionic and metal composition of bulk deposition at seven urban sites.  相似文献   

How effective are plant macrofossils as a proxy for macrophyte presence? The case of <Emphasis Type="Italic">Najas flexilis</Emphasis> in Scotland     

Isabel J. Bishop  Helen Bennion  Ian R. Patmore  Carl D. Sayer 《Journal of Paleolimnology》2018,60(2):153-165

Preventing biodiversity loss is a key aim of modern conservation, and paleolimnology can inform conservation strategies for target species and habitats where other data are unavailable. Care must be taken to fully understand the possibilities and limits of such techniques, particularly where they concern single species. This study uses plant and seed distribution data to inform macrofossil reconstructions of the rare macrophyte Najas flexilis (Slender Naiad) in Scotland, UK. It answers three questions: (a) How does the location of N. flexilis seeds in the surface sediments relate to the distribution of N. flexilis plants? (b) How do the numbers of seeds in surface sediments correlate with % cover of N. flexilis plants across lakes with differing N. flexilis abundances? (c) What are the implications of these findings for paleolimnology? Percentage N. flexilis cover and number of N. flexilis seeds in surface sediments were recorded at ~100 sample points at each of three sites; one where the species was abundant, one where it was occasional and one where it was extinct. At all sites, N. flexilis seeds were present in surface sediments across the entire lake. No correlation between % cover N. flexilis and the number of seeds in surface sediments was found within individual sites. The distribution of seeds in these lakes appeared to be related to multiple environmental and ecological variables including latitude and longitude (proxies for water currents). This is attributed to the ability of seed-bearing N. flexilis plants to fragment and float large distances on water. Between sites, there was a significant difference in the mean seed counts, with higher mean seed counts corresponding to higher abundances of N. flexilis plants. It is concluded that N. flexilis is likely to be well represented in sediment cores taken from any location within a basin, but that care should be taken when inferring changes in N. flexilis abundance from changes in the numbers of seeds in sediment samples. This work demonstrates that the reproductive ecology (number of seeds produced and dispersal mechanisms) is an important factor to consider when attempting reconstructions of single aquatic plant populations from macrofossil records.  相似文献