Avalanche zoning in alaska, U.S.A.

AbstractOver 30% of Alaska’s 586 400 squares miles (1 518900 km2) is subject to snow-avalanche activity. For a state-wide avalanche hazard evaluation, Alaska has been divided into six major snow— avalanche regions on the basis of topography, climatological data, dominant snow—pack conditions, and typical avalanche activity. They are: Arctic Slope, Brooks Range, Western, Interior, South—central, and South—east.Mountainous terrain was studied at scales of 1 : 250 000 and 1 : 1 584000; final compilation was at a scale of 1 : 2 500 000. Regional snow—pack and climatic conditions were cross—correlated with relief zonation of each avalanche region to produce a map of Alaska's provisional snow—avalanche potential.Most of the mountainous areas in the South—central and South—east regions, because of their northern latitude, closeness to large masses of water, and large orographic and cylonic weather processes, are susceptible to major avalanche activity. For areas near population centers, the potential avalanche terrain has been identified from data on known and suspected avalanche activity through air photographs, terrain analysis, and documented snow—avalanche occurrences compiled at scales of 1 : 250 000 and 1 : 63 360.The state—wide regional data compilation and study are initial steps toward avalanche zoning in Alaska. Local land—use planning and detailed investigations are needed to establish effective natural—hazard zoning in municipal areas as related to snow avalanche activity.

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A bioclimatic index of human survival times in the Antarctic

Polar Record ◽

10.1017/s0032247400008354 ◽

1987 ◽

Vol 23 (147) ◽

pp. 651-659 ◽

Cited By ~ 14

Author(s):

C. R. de Freitas ◽

L. V. Symon

Keyword(s):

Core Temperature ◽

Climatic Conditions ◽

Survival Times ◽

Climatological Data ◽

Human Survival ◽

Winter Conditions ◽

Normal Core ◽

Bioclimatic Index ◽

Extreme Cold ◽

The Antarctic

AbstractAn index of human ‘survival time outdoors in extreme cold’ (STOEC) has been developed, using body-atmosphere energy budget modelling procedures. The index, which is applicable in places like Antarctica where only limited climatological data are available, is based on the calculated rate of fall of core temperature from 37°C to 27°C of a standard inactive healthy subject in full polar clothing.Applied to data from 12 Antarctic stations it indicates relative severity of their mean and extreme climatic conditions. The severest winter conditions become lifethreatening after only about 20 minutes. At most stations in winter, exposure outdoors for more than two hours would be dangerous. Conditions at all coastal stations in summer are mildenough to allow a normal core temperature to be maintained. The index has many applications, for example estimating likely survival times of immobilized accident victims and guidelines for duration of work periods outside.

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A new multi-proxy record of environmental change over the last 1000 years on Chiloé Island: Lake Pastahué, south-central Chile (42°S)

The Holocene ◽

10.1177/0959683618816492 ◽

2018 ◽

Vol 29 (3) ◽

pp. 421-431

Author(s):

J Max Troncoso Castro ◽

Carolina Vergara ◽

Denisse Alvarez ◽

Gustavo Díaz ◽

Pablo Fierro ◽

...

Keyword(s):

Anthropogenic Activities ◽

Biological Indicator ◽

Climatic Conditions ◽

Ice Age ◽

Forest Composition ◽

Central Chile ◽

Lake Ecosystems ◽

South Central ◽

Recent Part ◽

Patagonian Forest

Knowledge of past environmental and climatic conditions of lake ecosystems on Chiloé Island on a millennial scale is limited. Hence, this study fills a gap in our understanding of this part of southern Chile. The aim of this study was to reconstruct the environmental and climatic history of the last 1000 years of Lake Pastahué through a multi-proxy sediment core analysis. The 1-m-long core was subsampled every centimeter for the organic matter, magnetic susceptibility, grain-size distribution, and biological indicator (pollen, chironomids) analyses. The age model was constructed from 210Pb, 137Cs, and 14C activity. Pollen results revealed a North Patagonian forest composition represented by Nothofagus, Weinmannia, Drimys, Tepualia, Myrtaceae, Poaceae, and Pteridophyta. The abundance of Rumex and Pinus in the most recent part of the pollen assemblage reflects a clear anthropogenic impact. The sedimentological parameters and chironomid assemblage show similar variations, which highlight changes in the trophic state of the lake. The changes observed in all proxies suggest the influence of climate events such as the ‘Medieval Climate Anomaly’ (MCA) and ‘Little Ice Age’ (LIA). The variations observed since the beginning of the 20th century could be the result of the combined effect of anthropogenic activities and the increase in temperature recorded in south-central Chile and Patagonia.

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Testing the simple and complex versions of Gloger’s rule in the Variable Antshrike (Thamnophilus caerulescens, Thamnophilidae)

The Auk ◽

10.1093/auk/ukaa026 ◽

2020 ◽

Vol 137 (3) ◽

Cited By ~ 2

Author(s):

Rafael S Marcondes ◽

Katherine Faust Stryjewski ◽

Robb T Brumfield

Keyword(s):

Species Distribution ◽

Negative Correlation ◽

Climatic Conditions ◽

Color Variation ◽

South American ◽

Plumage Color ◽

Simple Version ◽

South Central ◽

Color Data ◽

Gloger’S Rule

Abstract Gloger’s rule is a classic ecogeographical principle that, in its simplest version, predicts animals should be darker in warmer and wetter climates. In a rarely tested more complex version, it also predicts animals should be more rufous in warmer and drier climates. The Variable Antshrike (Thamnophilus caerulescens) is a widely distributed South American passerine that presents an impressive amount of plumage color variation and occupies a wide variety of climatic conditions. Moreover, genetic and vocal evidence indicate ongoing hybridization in south-central Bolivia among 3 populations with very distinct plumages. We collected color data from 232 specimens from throughout this species’ distribution to test the predictions of Gloger’s rule. We found a negative correlation between brightness and precipitation, consistent with the simple version of Gloger’s rule. In contrast, we found that birds were darker in cooler climates, contrary to the simple version of Gloger’s rule, but consistent with recent findings in other taxa. We found support for both predictions of the complex Gloger’s rule and suggest it might be driven by background matching. We conclude by concurring with a recent suggestion that the simple version of Gloger’s rule should be reformulated exclusively in terms of humidity.

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Dropstones in Lacustrine Sediments as a Record of Snow Avalanches—A Validation of the Proxy by Combining Satellite Imagery and Varve Chronology at Kenai Lake (South-Central Alaska)

Quaternary ◽

10.3390/quat2010011 ◽

2019 ◽

Vol 2 (1) ◽

pp. 11 ◽

Cited By ~ 2

Author(s):

Sien Thys ◽

Maarten Van Daele ◽

Nore Praet ◽

Britta Jensen ◽

Thomas Van Dyck ◽

...

Keyword(s):

Climate Change ◽

Lake Sediments ◽

Satellite Imagery ◽

Variable Temperature ◽

Sediment Cores ◽

Snow Avalanche ◽

Snow Avalanches ◽

Climate Data ◽

Varve Chronology ◽

South Central

Snow avalanches cause many fatalities every year and damage local economies worldwide. The present-day climate change affects the snowpack and, thus, the properties and frequency of snow avalanches. Reconstructing snow avalanche records can help us understand past variations in avalanche frequency and their relationship to climate change. Previous avalanche records have primarily been reconstructed using dendrochronology. Here, we investigate the potential of lake sediments to record snow avalanches by studying 27 < 30-cm-long sediment cores from Kenai Lake, south-central Alaska. We use X-ray computed tomography (CT) to image post-1964 varves and to identify dropstones. We use two newly identified cryptotephras to update the existing varve chronology. Satellite imagery is used to understand the redistribution of sediments by ice floes over the lake, which helps to explain why some avalanches are not recorded. Finally, we compare the dropstone record with climate data to show that snow avalanche activity is related to high amounts of snowfall in periods of relatively warm or variable temperature conditions. We show, for the first time, a direct link between historical snow avalanches and dropstones preserved in lake sediments. Although the lacustrine varve record does not allow for the development of a complete annual reconstruction of the snow avalanche history in the Kenai Lake valley, our results suggest that it can be used for long-term decadal reconstructions of the snow-avalanche history, ideally in combination with similar records from lakes elsewhere in the region.

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Effects of Different Land Uses (Abandoned Farmland, Intensive Agriculture and Forest) on Soil Hydrological Properties in Southern Spain

Water ◽

10.3390/w11030503 ◽

2019 ◽

Vol 11 (3) ◽

pp. 503 ◽

Cited By ~ 13

Author(s):

Manuel Lucas-Borja ◽

Demetrio Zema ◽

Pedro Plaza-Álvarez ◽

Vesna Zupanc ◽

Jantiene Baartman ◽

...

Keyword(s):

Land Use Planning ◽

Climatic Conditions ◽

Water Infiltration ◽

Southern Spain ◽

Intensive Agriculture ◽

Detailed Knowledge ◽

Land Uses ◽

Infiltration Capacity ◽

Abandoned Farmland ◽

Mediterranean Areas

A detailed knowledge of soil water repellency (SWR) and water infiltration capacity of soils under different land uses is of fundamental importance in Mediterranean areas, since these areas are prone to soil degradation risks (e.g., erosion, runoff of polluting compounds) as a response to different hydrological processes. The present study evaluates the effects of land uses on SWR and soil hydraulic conductivity (SHC) by direct measurements at the plot scale in three areas representing (1) intensive agricultural use, (2) abandoned farmland, and (3) a forest ecosystem in Southern Spain under Mediterranean climatic conditions. The physico-chemical properties and water content of the experimental soils were also measured. Significant SWR and SHC differences were found among the analyzed land uses. Forest soils showed high SWR and low SHC, while the reverse effects (that is, low SWR and high SHC) were detected in soils subjected to intensive agriculture. Organic matter and bulk density were important soil properties influencing SWR and SHC. The study, demonstrating how land uses can have important effects on the hydrological characteristics of soils, give land managers insights into the choice of the most suitable land use planning strategies in view of facing the high runoff and erosion rates typical of the Mediterranean areas.

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Reconstructing snow-avalanche activity with tree rings in Maramureş Mountains (Eastern Carpathians, Romania)

10.5194/egusphere-egu2020-20060 ◽

2020 ◽

Author(s):

Armelle Decaulne ◽

Ionela-Georgiana Răchită ◽

Mihai Hotea ◽

Vasile Timur Chiş ◽

Olimpiu Traian Pop

Keyword(s):

Tree Ring ◽

Tree Rings ◽

Climatic Factors ◽

Climatic Conditions ◽

Snow Avalanche ◽

Snow Avalanches ◽

Joint Research ◽

Eastern Carpathians ◽

Joint Research Project ◽

Callus Tissues

Snow avalanches represent a common phenomenon in Maramure&#351; Mountains (Eastern Carpathians, Romania) where they occur frequently on higher steep slopes and reach in the runout zones the valley bottoms below 1000 m a.s.l. The presence of particular topo-climatic conditions influences the patterns of avalanche activity in terms of past frequency and spatial extent along the slope valleys. As the past snow-avalanche activity is not documented by written reports in the area, reliable information about avalanche history is missing. However, the slopes are forested, trees repeatedly disturbed by snow avalanches record evidence of past events. For this study we reconstructed the avalanche activity using tree rings as a source of proxy data. To date the snow-avalanche history, dendrochronological investigations have been carried out in two avalanche paths, along which living trees showed clear external signs of past disturbances related to mechanical impacts produced by snow avalanches. In each investigated path, a total number of 52 and respectively 118 trees have been sampled and their spatial position recorded with a GPS device. Tree-growth anomalies (e.g. scars, callus tissues, the onset sequences of tangential rows of traumatic resin ducts, compression wood, growth suppression and release sequences) related to snow avalanche disturbance identified within tree rings served to reconstruct past events with an annual resolution. The results indicate that, apart the 2005 major event witnessed and also confirmed by tree-ring dating, multiple other events have been reconstructed since the beginning of 20th century. Despite some inherent limitations of tree-ring methods in reconstructing past avalanche events, these dendrochronological investigations confirm their utility in deciphering the patterns of avalanche activity in Maramure&#351; Mountains. Tree-ring studies contribute to a better understanding of the role of topographical and climatic factors which influence the spatio-temporal occurrence of snow avalanches.This study represents a contribution to the joint research project 09-AUF, &#8216;&#8216;Activit&#233; des avalanches de neige dans les Carpates Orientales Roumaines et Ukrainiennes - ACTIVNEIGE&#8217;&#8217;, co-funded by the Agence Universitaire de la Francophonie (AUF) and Institutul de Fizic&#259; Atomic&#259; (IFA), Romania.

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Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1700327114 ◽

2017 ◽

Vol 114 (25) ◽

pp. 6474-6479 ◽

Cited By ~ 17

Author(s):

William H. Amidon ◽

G. Burch Fisher ◽

Douglas W. Burbank ◽

Patricia L. Ciccioli ◽

Ricardo N. Alonso ◽

...

Keyword(s):

Southern Hemisphere ◽

Central Andes ◽

Climatic Conditions ◽

The South ◽

Climate History ◽

Faunal Turnover ◽

Erosion Rates ◽

South Central ◽

Terrestrial Life ◽

Earth’S Climate

Although Earth’s climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from ∼6.2–5.5 Ma and with the Messinian Salinity Crisis from ∼6.0–5.3 Ma. Despite the climatic and ecological significance of this period, the continental climatic conditions associated with it remain unclear. We address this question using erosion rates of ancient watersheds to constrain Mio-Pliocene climatic conditions in the south-central Andes near 30° S. Our results show two slowdowns in erosion rate, one from ∼6.1–5.2 Ma and another from 3.6 to 3.3 Ma, which we attribute to periods of continental aridity. This view is supported by synchrony with other regional proxies for aridity and with the timing of glacial ‟cold” periods as recorded by marine proxies, such as the M2 isotope excursion. We thus conclude that aridity in the south-central Andes is associated with cold periods at high southern latitudes, perhaps due to a northward migration of the Southern Hemisphere westerlies, which disrupted the South American Low Level Jet that delivers moisture to southeastern South America. Colder glacial periods, and possibly associated reductions in atmospheric CO2, thus seem to be an important driver of Mio-Pliocene ecological transitions in the central Andes. Finally, this study demonstrates that paleo-erosion rates can be a powerful proxy for ancient continental climates that lie beyond the reach of most lacustrine and glacial archives.

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Snow Avalanche Hazard Zoning in British Columbia, Canada

Journal of Glaciology ◽

10.3189/s0022143000010881 ◽

1980 ◽

Vol 26 (94) ◽

pp. 345-354 ◽

Cited By ~ 1

Author(s):

G. L. Freer ◽

P. A. Schaerer

Keyword(s):

Land Use ◽

British Columbia ◽

Safety Factor ◽

Snow Avalanche ◽

The Past ◽

Avalanche Hazard ◽

Hazard Zoning ◽

Technical Considerations

AbstractMany developed areas in British Columbia are exposed to snow-avalanche hazards. Avalanche-hazard zoning has been undertaken by the British Columbia Ministry of Transportation, Communications, and Highways during the past five years. Recommendations from these zoning studies are forwarded to those agencies responsible for land-use zoning and development approval. Existing and possible legislation are described, as well as problems associated with implementation of the legislation. Technical considerations are outlined; interpretation of vegetation is a very important factor in evaluating each avalanche site. Calculation of run-out distances and consideration of other factors serve as a check on the vegetation interpretation. A special safety factor has been developed.Socio-political considerations with respect to British Columbia are described. Existing developments have the most wide-ranging implications.

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Wastage of the Klutlan Ice-Cored Moraines, Yukon Territory, Canada

Quaternary Research ◽

10.1016/0033-5894(80)90005-8 ◽

1980 ◽

Vol 14 (1) ◽

pp. 31-49 ◽

Cited By ~ 31

Author(s):

Fletcher G. Driscoll

Keyword(s):

Heat Flux ◽

Lake Water ◽

Seismic Data ◽

Sediment Concentration ◽

Climatic Conditions ◽

Yukon Territory ◽

Climatic Parameters ◽

Geothermal Heat ◽

Climatological Data

AbstractA series of ice-cored Neoglacial moraines at the terminus of the Klutlan Glacier covers an area of 90 km2. Studies were made to determine empirically how long ice persisted in the Klutlan moraines and to develop models that can accurately predict wastage rates under current climatic conditions. A meltout curve based on climatological data reflects the sum of three melting processes: surficial melting, melting by lake water, and melting by geothermal heat. About 950 yr are required to melt 180 m of ice with a debris concentration of 1%, or about 1200 yr for a 1.5% debris load. Another meltout curve, based on seismic data, suggests total meltout in about 875 yr. When all geologic factors are considered, the empirical meltout curve is remarkably similar to that derived by considering the major heat-flux parameters. Meltout rates can be predicted if (1) the fundamental climatic parameters can be ascertained, and (2) the sediment concentration in the ice is known.

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