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Hazardous processes and events from glacier and permafrost areas: lessons from the Chilean and Argentinean Andes 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Glacier and permafrost hazards such as glacial‐lake outburst floods and rock–ice avalanches cause significant socio‐economic damages worldwide, and these processes may increase in frequency and magnitude if the atmospheric temperature rises. In the extratropical Andes nearly 200 human deaths were linked to these processes during the twentieth century. We analysed bibliographical sources and satellite images to document the glacier and permafrost dynamics that have caused socio‐economic damages in this region in historic time (including glacial lake outburst floods, ice and rock–ice avalanches and lahars) to unravel their causes and geomorphological impacts. In the extratropical Andes, at least 15 ice‐dammed lakes and 16 moraine‐dammed lakes have failed since the eighteenth century, causing dozens of floods. Some floods rank amongst the largest events ever recorded (5000 × 106 m3 and 229 × 106 m3, respectively). Outburst flood frequency has increased in the last three decades, partially as a consequence of long‐term (decades to centuries) climatic changes, glaciers shrinkage, and lake growth. Short‐term (days to weeks) meteorological conditions (i.e. intense and/or prolonged rainfall and high temperature that increased meltwater production) have also triggered outburst floods and mass movements. Enormous mass failures of glaciers and permafrost (> 10 × 106 m3) have impacted lakes, glaciers, and snow‐covered valleys, initiating chain reactions that have ultimately resulted in lake tsunamis and far‐reaching (> 50 km) flows. The eruption of ice‐covered volcanoes has also caused dozens of damaging lahars with volumes up to 45 × 106 m3. Despite the importance of these events, basic information about their occurrence (e.g. date, causes, and geomorphological impact), which is well established in other mountain ranges, is absent in the extratropical Andes. A better knowledge of the processes involved can help to forecast and mitigate these events. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Diaz Hector Mazzorana Bruno Gems Bernhard Rojas Ivan Santibañez Nicole Iribarren Pablo Pino Mario Iroumé Andrés 《Natural Hazards》2022,111(3):3099-3120
Sudden avulsions, unexpected channel migrations and backfilling phenomena are autogenic phenomena that can considerably change the propagation patterns of sediment-laden flows on alluvial fans. Once the initial and boundary conditions of the hazard scenario with a given return period are determined, the assessment of the associated exposed areas is based on one numerical, essentially deterministic, process simulation which may not adequately capture the underlying process variability. We generated sediment-laden flows on an experimental alluvial fan by following a “similarity-of-process concept”. Specifically, we considered a convexly shaped alluvial fan model layout featuring a curved guiding channel. As loading conditions, we defined a reference, an increased and a reduced level for the released water volume and the predisposed solid fraction, respectively. Further, we imposed two different stream power regimes and accomplished, for each factor combination, eight experimental runs. The associated exposure areas were recorded by video and mapped in a GIS. We then analysed exposure data and determined exposure probability maps superposing the footprints of the eight repetitions associated with each experimental loading condition. The patterns of exposure referred to the specific loading conditions showed a noticeable variability related to the main effects of the total event volume, the solid fraction, the interactions between them, and the imposed stream power in the feeding channel. Our research suggests that adopting a probabilistic notion of exposure in risk assessment and mitigation is advisable. Further, a major challenge consists in adapting numerical codes to better reflect the stochastics of process propagation for more reliable flood hazard assessments.
相似文献3.
Pablo Iribarren Anacona Kevin Norton Andrew Mackintosh Fernando Escobar Simon Allen Bruno Mazzorana Marius Schaefer 《Natural Hazards》2018,92(1):93-112
The rise of total water levels at the coast is caused primarily by three factors that encompass storm surges, tides and wind waves. The accuracy of total water elevation (TWE) forecast depends not only on the cyclonic track and its intensity, but also on the spatial distribution of winds which include its speed and direction. In the present study, the cyclonic winds are validated using buoy winds for the recent cyclones formed in the Bay of Bengal since 2010 using Jelesnianski wind scheme. It is found that the cyclonic winds computed from the scheme show an underestimate in the magnitude and also a mismatch in its direction. Hence, the wind scheme is suitably modified based on the buoy observations available at different locations using a power law which reduces the exponential decay of winds by about 30%. Moreover, the cyclonic wind direction is also corrected by suitably modifying its inflow angle. The significance of modified exponential factor and inflow angle in the computation cyclonic winds is highlighted using statistical analysis. A hydrodynamic finite element-based Advanced Circulation 2D depth integrated (ADCIRC-2DDI) model is used here to compute TWE as a response to combined effect of cyclonic winds and astronomical tides. As contribution of wave setup plays an important role near the coast, a coupled ADCIRC + SWAN is used to perceive the contribution of wind waves on the TWE. The experiments are performed to validate computed surge residuals with available tide gauge data. On comparison of observed surge residuals with the simulations using modified winds from the uncoupled and coupled models, it is found that the simulated surge residuals are better compared, especially with the inclusion of wave effect through the coupled model. 相似文献
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Geochemistry and mineralogy of surface pyritic tailings impoundments at two mining sites of the Iberian Pyrite Belt (SW Spain) 总被引：2，自引：2，他引：0
J. C. Arranz González V. Cala Rivero I. Iribarren Campaña 《Environmental Earth Sciences》2012,65(3):669-680
Two pyritic tailings impoundments located in two mining areas of the Iberian Pyrite Belt (Cueva de la Mora and Minas de Ríotinto-Zarandas)
were selected to asses their potential environmental impact. Mineralogical (XRD diffraction study), physico-chemical characterization
(colour, particle size, pH, acid–base account, total Fe, As, Cu, Pb and Zn) as well as a speciation study (by means of a seven-step
sequential extraction procedure) were performed in superficial (0–20 cm) tailings samples. Arsenic and metal contents in soils
around the tailings impoundments were also studied. Zarandas dam, a reclaimed impoundment, which has been limed, partially
topsoiled and planted, has supported and allowed the growth of pine trees and other plants for many years. The surface of
this impoundment can be considered very acid but nonacid forming. Although total As and metal concentrations were relatively
high, it is not possible to conclude that the Zarandas tailings have polluted the surrounding soils. Tailings in Cueva de
la Mora showed high total and easily mobilizable concentration of toxic elements. The net neutralization potential was strongly
negative as a consequence of the acid generation caused by the sulphide oxidation, the presence of secondary acid-generating
minerals and the absence of neutralizing materials. Coquimbite and rhomboclase efflorescences formed during the Mediterranean
dry summers on the surface of this impoundment contained very high levels of soluble As, Cu and Zn that were easily dissolved
and released to the running water in the first rains of autumn. 相似文献
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We present a quantification of total and partial (divided by time slices) sedimentary volumes in the Neogene basins of the Betic-Rif orogen. These basins include the Alboran Sea, the intramontane basins, the Guadalquivir and Rharb foreland basins and the Atlantic Margin of the Gibraltar Arc. The total volume of Neogene sediments deposited in these basins is ~ 209,000 km3 and is equally distributed between the internal (Alboran Basin and intramontane basins) and the external basins (foreland basins and Atlantic Margin). The largest volumes are recorded by the Alboran Basin (89,600 km3) and the Atlantic Margin (81,600 km3). The Guadalquivir and Rharb basins amount 14,000 km3 and 14,550 km3, respectively whereas the intramontane basins record 9235 km3. Calculated mean sediment accumulation rates for the early-middle Miocene show an outstanding asymmetry between the Alboran basin (0.24 mm/yr) and the foreland basins (0.06-0.07 mm/yr) and the Atlantic Margin (0.03 mm/yr). During the late Miocene, sedimentation rates range between 0.17 and 0.18 mm/yr recorded in the Alboran Basin and 0.04 mm/yr in the intramontane basins. In the Pliocene-Quaternary, the highest sedimentation rates are recorded in the Atlantic Margin reaching 0.22 mm/yr. Sedimentary contribution shows similar values for the inner and outer basins with a generalized increase from late Miocene to present (from 3500 to 6500 km3/My). Interestingly, the Alboran Basin records the maximum sedimentary contribution during the late Miocene (5500 km3/My), whereas the Atlantic Margin does during the Pliocene-Quaternary (6600 km3/My). The spatial and time variability of the sediment supply from the Betic-Rif orogen to basins is closely related to the morphotectonic evolution of the region. The high sedimentation rates obtained in the Alboran Basin during the early-middle Miocene are related to active extensional tectonics, which produced narrow and deep basins in its western domain. The highest sedimentary contribution in this basin, as well as in the foreland and intramontane basins, is recorded during the late Miocene due to the uplift of wide areas of the Betics and Rif chains. The analysis of the sedimentary supply also evidences strong relationships with the post-Tortonian crustal thickening and coeval topographic amplification that occurred in the central Betics and Rif with the concomitant evolution of the drainage network showing the fluvial capture of some internal basins by rivers draining to the Atlantic Ocean (the ancestral Guadalquivir). 相似文献
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