Predicting small business demise after a natural disaster: an analysis of pre-existing conditions     

Maria I. Marshall  Linda S. Niehm  Sandra B. Sydnor  Holly L. Schrank 《Natural Hazards》2015,79(1):331-354

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Response of suspended sediment particle size distributions to changes in water chemistry at an Andean mountain stream confluence receiving arsenic rich acid drainage          下载免费PDF全文

Maria Abarca  Paula Guerra  Guillermo Arce  Mauricio Montecinos  Cristian Escauriaza  Marina Coquery  Pablo Pastén 《水文研究》2017,31(2):296-307

Acid drainage is an important water quality issue in Andean watersheds, affecting the sustainability of urban, agricultural, and industrial activities. Mixing zones receiving acid drainage are critical sites where changes in pH and chemical environment promote the formation and dissolution of iron and aluminum oxy/hydroxides. These particles can significantly change the speciation of toxic metals and metalloids throughout drainage networks via sorption, desorption, and settling processes. However, little is known about the behavior of particle size distributions (PSDs) in streams affected by acid drainage and their relationship to metal speciation. This work studied: (a) the PSDs for a wide range of mixing ratios found at a fluvial confluence affected by acid drainage, and (b) the response of PSDs and arsenic speciation to environmental changes found when the particles approach complete mixing conditions. The confluence between the Azufre River (pH ~ 2, high concentration of dissolved metals) and Caracarani River (pH = 8.6, low concentration of dissolved metals) was used as a representative model for study. Field measurements show a bimodal PSD with modal diameters of ~50 and 300 μm. At shorter distances from the junction, the smaller modes with smaller particle volumes were dominant across the stream cross‐sections. A systematic shift towards larger particle sizes and larger particle volumes occurred downstream. The analysis of laboratory PSDs for Azufre/Caracarani mixing ratios between 0.01 and 0.5 (pH from 6.2 to 2.3) showed a bimodal trend with ~15 and 50 μm characteristic diameters; larger particles formed at pH>4. When particle suspensions were transferred in laboratory experiments from very low pH to full mixing conditions (pH ~ 2.8 and mixing ratio ~ 0.25) particle sizes varied, and the dissolved arsenic concentration decreased. The observed reaction kinetics were slow compared to the time scale of advective transport, creating opportunities for engineered controls for arsenic. This work contributes to a better understanding of the chemical‐hydrodynamic interactions in watersheds affected by mining, and identifying opportunities to improve water quality at points of use.  相似文献   

Understory and small trees contribute importantly to stemflow of a lower montane cloud forest          下载免费PDF全文

Teresa Margarita González‐Martínez  Guadalupe Williams‐Linera  Friso Holwerda 《水文研究》2017,31(5):1174-1183

Stemflow (Sf) measurements in tropical rain and montane forests dominated by large trees rarely include the understory and small trees. In this study, contributions of lower (1‐ to 2‐m height) and upper (>2‐m height and <5‐cm diameter at breast height [DBH]) woody understory, small trees (5 < DBH < 10 cm), and canopy trees (>10‐cm DBH) to Sf per unit ground area (Sf_a) of a Mexican lower montane cloud forest were quantified for 32 days with rainfall (P) during the 2014 wet season. Rainfall, stemflow yield (Sf_y), vegetation height, density, and basal area were measured. Subsequently, stemflow funneling ratios (SFRs) were calculated, and three common methods to scale up Sf_y from individual trees to the stand level (tree‐Sf_y correlation, P‐Sf_y correlation, and mean‐Sf_y extrapolation) were used to calculate Sf_a. Understory woody plants, small trees, and upper canopy trees represented 96%, 2%, and 2%, respectively, of the total density. Upper canopy trees had the lowest SFRs (1.6 ± 0.5 Standard Error (SE) on average), although the lower understory had the highest (36.1 ± 6.4). Small trees and upper understory presented similar SFRs (22.9 ± 5.4 and 20.2 ± 3.9, respectively). Different Sf scaling methods generally yielded similar results. Overall Sf_a during the study period was 22.7 mm (4.5% of rainfall), to which the understory contributed 70.1% (15.9 mm), small trees 10.6% (2.4 mm), and upper canopy trees 19.3% (4.4 mm). Our results strongly suggest that for humid tropical forests with dense understory of woody plants and small trees, Sf of these groups should be measured to avoid an underestimation of overall Sf at the stand level.  相似文献   

A GLUE‐based uncertainty assessment framework for tritium‐inferred transit time estimations under baseflow conditions          下载免费PDF全文

Francesc Gallart  Maria Roig‐Planasdemunt  Michael K. Stewart  Pilar Llorens  Uwe Morgenstern  Willibald Stichler  Laurent Pfister  Jérôme Latron 《水文研究》2016,30(25):4741-4760

The last decade has seen major technical and scientific improvements in the study of water transfer time through catchments. Nevertheless, it has been argued that most of these developments used conservative tracers that may disregard the oldest component of water transfer, which often has transit times greater than 5 years. Indeed, although the analytical reproducibility of tracers limits the detection of the older flow components associated with the most dampened seasonal fluctuations, this is very rarely taken into account in modelling applications. Tritium is the only environmental tracer at hand to investigate transfer times in the 5‐ to 50‐year range in surface waters, as dissolved gases are not suitable due to the degassing process. Water dating with tritium has often been difficult because of the complex history of its atmospheric concentration, but its current stabilization together with recent analytical improvements open promising perspectives. In this context, the innovative contribution of this study lies in the development of a generalized likelihood uncertainty estimation‐based approach for analysing the uncertainties associated with the modelling of transit time due to both parameter identification and tracer analytical precision issues. A coupled resampling procedure allows assessment of the statistical significance of the transfer time differences found in diverse waters. This approach was developed for tritium and the exponential‐piston model but can be implemented for virtually any tracer and model. Stream baseflow, spring and shallow aquifer waters from the Vallcebre research catchments, analysed for tritium in different years with different analytical precisions, were investigated by using this approach and taking into account other sources of uncertainty. The results showed three groups of waters of different mean transit times, with all the stream baseflow and spring waters older than the 5‐year threshold needing tritium. Low sensitivity of the results to the model structure was also demonstrated. Dual solutions were found for the waters sampled in 2013, but these results may be disambiguated when additional analyses will be made in a few years. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Improving Properties of Sealing Layers Made of Till by Adding Green Liquor Dregs to Reduce Oxidation of Sulfidic Mine Waste     

Maria Mäkitalo  Josef Mácsik  Christian Maurice  Björn Öhlander 《Geotechnical and Geological Engineering》2015,33(4):1047-1054

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Reconstruction of long-term earth-flow activity using a hydroclimatological model     

Luigi Guerriero  Nazzareno Diodato  Francesco Fiorillo  Paola Revellino  Gerardo Grelle  Francesco Maria Guadagno 《Natural Hazards》2015,77(1):1-15

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Exploring lava‐flow hazards at Pico Island,Azores Archipelago (Portugal)          下载免费PDF全文

Annalisa Cappello  Vittorio Zanon  Ciro Del Negro  Teresa J. L. Ferreira  Maria G. P. S. Queiroz 《地学学报》2015,27(2):156-161

Pico, the youngest island of the Azores Archipelago (Portugal), is characterized by a central volcano and a 30‐km‐long fissure zone. Its eruption rate is the highest of the Azores islands, with more than 35 eruptions in the last 2000 years. Here, we estimate the lava‐flow hazard for Pico Island by combining the vent opening probability derived from the spatial distribution of eruptive fissures, the classes of expected eruptions inferred from the physical and chemical characteristics of historical eruptions, and the lava‐flow paths simulated by the MAGFLOW model. The most likely area to host new eruptions is along a WNW–ESE trend centred on the central volcano, with the highest hazard affecting the two main residential zones of Lajes do Pico and Madalena. Our analysis is the first attempt to assess the lava‐flow hazard for Pico Island, and may have important implications for decision‐making in territorial management and future land‐use planning.  相似文献   

Detecting the stepwise propagation of the Eastern Sicily thrust belt (Italy): insight from thermal and thermochronological constraints     

Lea Di Paolo  Valerio Olivetti  Sveva Corrado  Luca Aldega  Maria Laura Balestrieri  Rosanna Maniscalco 《地学学报》2014,26(5):363-371

An extensive dataset of vitrinite reflectance, FTIR parameters on organic matter, illite content in mixed layers illite‐smectite, apatite fission tracks and U‐Th/He dating has been used to reconstruct the stepwise propagation of the Eastern Sicily fold‐and‐thrust belt during Late Palaeogene and Neogene times. The results indicate that the fold‐and‐thrust belt is divisible into two levels of thermal maturity. These levels consist of a less evolved level of thermal maturity that records limited sedimentary burial and minor heating, and a more evolved level of thermal maturity that indicates tectonic burial and exhumation at different times. Deformation and exhumation of shallowly buried units are linked to wedge forward propagation by low‐angle thrusts, whereas the evolution of deeply buried units is associated with tectonic imbrications by duplex formation and steep thrusts. The two tectonic styles alternate during evolution of the fold‐and‐thrust belt under low erosion rates.  相似文献   

Evaluating the impact and uncertainty of reservoir operation for malaria control as the climate changes in Ethiopia     

Julia Reis  Teresa B. Culver  Paul J. Block  Matthew P. McCartney 《Climatic change》2016,136(3-4):601-614

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Multispecies dendroclimatic reconstructions of summer temperature in the European Alps enhanced by trees highly sensitive to temperature     

Giovanni Leonelli  Anna Coppola  Carlo Baroni  Maria Cristina Salvatore  Maurizio Maugeri  Michele Brunetti  Manuela Pelfini 《Climatic change》2016,137(1-2):275-291

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