Pub Date : 2020-05-18DOI: 10.1080/04353676.2020.1763632
Maili Wu, Na Liu, G. Bao, Jinbo Gao
ABSTRACT Compared with traditional research methods, research based on physiological processes could provide more interactions between the radial growth of trees and climate factors. The Vaganov–Shashkin model (VS-oscilloscope) was applied to simulate tree-ring formation in semi-arid eastern Gansu, China and its response to climate variables during the past several decades. Three simulated tree-ring width series are significantly correlated to the corresponding measured tree-ring chronologies during their common periods (p < 0.001). The growth rate due to soil moisture dominates the radial growth of trees in the main growing season, and growth rate due to temperature limits tree growth at the start and end of the growing season. Simulation results show that soil moisture significantly affects tree-ring width in extremely wide and narrow rings years (p < 0.01). Correlation analysis between measured tree-ring chronologies and monthly climate data and divided periods simulation results show that the limiting effect of soil moisture on the radial growth of Pinus tabulaeformis under warm and dry conditions is significantly enhanced. Our results provide useful knowledge for improving the protection of forests in ecologically fragile areas and mitigating the adverse effects of warmer climate in the future.
{"title":"Climatic factors of radial growth of Pinus tabulaeformis in eastern Gansu, northwest China based on Vaganov–Shashkin model","authors":"Maili Wu, Na Liu, G. Bao, Jinbo Gao","doi":"10.1080/04353676.2020.1763632","DOIUrl":"https://doi.org/10.1080/04353676.2020.1763632","url":null,"abstract":"ABSTRACT\u0000 Compared with traditional research methods, research based on physiological processes could provide more interactions between the radial growth of trees and climate factors. The Vaganov–Shashkin model (VS-oscilloscope) was applied to simulate tree-ring formation in semi-arid eastern Gansu, China and its response to climate variables during the past several decades. Three simulated tree-ring width series are significantly correlated to the corresponding measured tree-ring chronologies during their common periods (p < 0.001). The growth rate due to soil moisture dominates the radial growth of trees in the main growing season, and growth rate due to temperature limits tree growth at the start and end of the growing season. Simulation results show that soil moisture significantly affects tree-ring width in extremely wide and narrow rings years (p < 0.01). Correlation analysis between measured tree-ring chronologies and monthly climate data and divided periods simulation results show that the limiting effect of soil moisture on the radial growth of Pinus tabulaeformis under warm and dry conditions is significantly enhanced. Our results provide useful knowledge for improving the protection of forests in ecologically fragile areas and mitigating the adverse effects of warmer climate in the future.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"33 1","pages":"196 - 208"},"PeriodicalIF":1.5,"publicationDate":"2020-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76224950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-14DOI: 10.1080/04353676.2020.1761097
J. Pandey, S. Sigdel, Xiaoming Lu, F. Salerno, B. Dawadi, E. Liang, J. Camarero
ABSTRACT Shrubs growing at higher latitudes and altitudes are considered to be highly sensitive to climate warming. In particular, alpine shrubs are potential climate proxies for understanding responses of high-elevation treeless ecosystems to warmer conditions. However, little is known about how alpine shrub radial growth responds to climate variables, specifically temperature and precipitation. This lack of knowledge is particularly notable in the Himalayas where shrubs reach some of their worldwide uppermost limits. Herein, we investigated the climatic response of alpine juniper shrub (Juniperus indica) to climate in two areas (dry Manang valley; wet Everest valley) situated in the central Himalayas. In spite of different sites and elevations, the radial growth of juniper shrub is positively correlated with spring precipitation in both areas, and also with summer precipitation in the dry area. Juniper shrub shares common climatic responses with Himalayan treeline tree populations, whose growth dynamics are also controlled by moisture availability. Thus, radial growth of juniper in the central Himalayas may experience drought stress if climate warming leads to drier conditions. We conclude that alpine shrubs are crucial indicators of the responses of alpine ecosystem to global climate warming.
{"title":"Early growing-season precipitation drives radial growth of alpine juniper shrubs in the central Himalayas","authors":"J. Pandey, S. Sigdel, Xiaoming Lu, F. Salerno, B. Dawadi, E. Liang, J. Camarero","doi":"10.1080/04353676.2020.1761097","DOIUrl":"https://doi.org/10.1080/04353676.2020.1761097","url":null,"abstract":"ABSTRACT Shrubs growing at higher latitudes and altitudes are considered to be highly sensitive to climate warming. In particular, alpine shrubs are potential climate proxies for understanding responses of high-elevation treeless ecosystems to warmer conditions. However, little is known about how alpine shrub radial growth responds to climate variables, specifically temperature and precipitation. This lack of knowledge is particularly notable in the Himalayas where shrubs reach some of their worldwide uppermost limits. Herein, we investigated the climatic response of alpine juniper shrub (Juniperus indica) to climate in two areas (dry Manang valley; wet Everest valley) situated in the central Himalayas. In spite of different sites and elevations, the radial growth of juniper shrub is positively correlated with spring precipitation in both areas, and also with summer precipitation in the dry area. Juniper shrub shares common climatic responses with Himalayan treeline tree populations, whose growth dynamics are also controlled by moisture availability. Thus, radial growth of juniper in the central Himalayas may experience drought stress if climate warming leads to drier conditions. We conclude that alpine shrubs are crucial indicators of the responses of alpine ecosystem to global climate warming.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"31 1","pages":"317 - 330"},"PeriodicalIF":1.5,"publicationDate":"2020-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91078907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-13DOI: 10.1080/04353676.2020.1761132
B. Sun, Yu Liu, Y. Lei, Yongyong Ma, Changfeng Sun
ABSTRACT In comparison to trees that grow in arid areas, those growing in humid areas usually have ambiguous climatic information recorded in their ring widths. In this study, ring width samples of Abies chensiensis, collected from the headwaters of the Jialing River in the mid-Qinling Mountains, were used to investigate if temperature signals from the ring widths of trees in humid areas can be extracted. By employing data processing techniques such as first-order difference processing of all series, correlation analysis using pentad meteorological data, and outlier elimination, we found that the inter-annual variations in the average minimum temperature of the pentad 10–23 (MT10–23) was the limiting factor for radial growth. In humid areas, the moisture content of the air and soil may weaken (or impede) the limiting effect of temperature on trees, and correlation results between chronology and temperature cannot meet the requirements of climate reconstruction, mainly due to the inconsistency of their low-frequency variations. Therefore, accurate extraction of high-frequency temperature signals may be the key to climate reconstruction from tree-ring widths in humid areas.
{"title":"Temperature variations extracted from ring widths of firs growing in the humid environment of the mid-Qinling Mountains","authors":"B. Sun, Yu Liu, Y. Lei, Yongyong Ma, Changfeng Sun","doi":"10.1080/04353676.2020.1761132","DOIUrl":"https://doi.org/10.1080/04353676.2020.1761132","url":null,"abstract":"ABSTRACT In comparison to trees that grow in arid areas, those growing in humid areas usually have ambiguous climatic information recorded in their ring widths. In this study, ring width samples of Abies chensiensis, collected from the headwaters of the Jialing River in the mid-Qinling Mountains, were used to investigate if temperature signals from the ring widths of trees in humid areas can be extracted. By employing data processing techniques such as first-order difference processing of all series, correlation analysis using pentad meteorological data, and outlier elimination, we found that the inter-annual variations in the average minimum temperature of the pentad 10–23 (MT10–23) was the limiting factor for radial growth. In humid areas, the moisture content of the air and soil may weaken (or impede) the limiting effect of temperature on trees, and correlation results between chronology and temperature cannot meet the requirements of climate reconstruction, mainly due to the inconsistency of their low-frequency variations. Therefore, accurate extraction of high-frequency temperature signals may be the key to climate reconstruction from tree-ring widths in humid areas.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"1 1","pages":"222 - 234"},"PeriodicalIF":1.5,"publicationDate":"2020-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81615270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-23DOI: 10.1080/04353676.2020.1751446
N. P. Gaire, Z. Fan, Santosh K. Shah, U. Thapa, M. Rokaya
ABSTRACT Tree rings are widely used to reconstruct past climates in regions where observational records of climate are short. In this study, we developed a 294 years-long (1718–2011 CE) ring-width chronology of the Himalayan Silver fir (Abies spectabilis (D.Don, Spach)) from Humla district in western Nepal to reconstruct winter minimum temperature for the remote region of central Himalaya where instrumental records are limited to past three or four decades. Ring-width chronology of the Himalayan Silver fir showed strongest and significant positive correlation with minimum winter temperature prior to the growing season. Based on this relationship, we reconstructed the winter season (previous October–current February) minimum temperature for western Nepal covering the period of 1780–2008 CE. Our reconstruction showed that winter minimum temperature is continuously increasing since the early twentieth century with unprecedented rapid warming in the latter half. The cold episodes in the reconstruction coincided with the major volcanic eruptions in the Northern Hemisphere and tropical regions. The spectral analysis using Multi-Taper Method revealed that the winter temperature in the north-western Himalaya has short- to medium-term periodicities of 2–3, 5.8–6.2, 7.9–8.2, 39–46 and 56–73 years, which suggest possible teleconnections with ENSO (El-Nino Southern Oscillation) and AMO (Atlantic Multidecadal Oscillation).
{"title":"Tree-ring record of winter temperature from Humla, Karnali, in central Himalaya: a 229 years-long perspective for recent warming trend","authors":"N. P. Gaire, Z. Fan, Santosh K. Shah, U. Thapa, M. Rokaya","doi":"10.1080/04353676.2020.1751446","DOIUrl":"https://doi.org/10.1080/04353676.2020.1751446","url":null,"abstract":"ABSTRACT\u0000 Tree rings are widely used to reconstruct past climates in regions where observational records of climate are short. In this study, we developed a 294 years-long (1718–2011 CE) ring-width chronology of the Himalayan Silver fir (Abies spectabilis (D.Don, Spach)) from Humla district in western Nepal to reconstruct winter minimum temperature for the remote region of central Himalaya where instrumental records are limited to past three or four decades. Ring-width chronology of the Himalayan Silver fir showed strongest and significant positive correlation with minimum winter temperature prior to the growing season. Based on this relationship, we reconstructed the winter season (previous October–current February) minimum temperature for western Nepal covering the period of 1780–2008 CE. Our reconstruction showed that winter minimum temperature is continuously increasing since the early twentieth century with unprecedented rapid warming in the latter half. The cold episodes in the reconstruction coincided with the major volcanic eruptions in the Northern Hemisphere and tropical regions. The spectral analysis using Multi-Taper Method revealed that the winter temperature in the north-western Himalaya has short- to medium-term periodicities of 2–3, 5.8–6.2, 7.9–8.2, 39–46 and 56–73 years, which suggest possible teleconnections with ENSO (El-Nino Southern Oscillation) and AMO (Atlantic Multidecadal Oscillation).","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"33 1","pages":"297 - 316"},"PeriodicalIF":1.5,"publicationDate":"2020-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89465809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/04353676.2020.1762364
Connor J. Shiggins, M. Harris, P. G. Knight, C. Fogwill
ABSTRACT Subglacial glaciohydraulic supercooling can form basal ice and affect glacier dynamics, sediment transfer and geomorphology. Whilst isotopic analysis (δ18O-δD) of basal ice has demonstrated the significance of supercooling, questions remain as to what extent the identification of supercooling depends on sampling resolution. We conducted laboratory experiments in which ice was frozen from supercooled water and sampled at a micro-scale (1.5 millilitre) to identify highly localized variations in isotopic compositions that might be lost in bulk-scale sampling. Three distinctive ice facies produced by the freezing process demonstrated diagnostic isotopic signatures that were distinguished when the facies were sampled independently. However, their respective isotopic signatures were lost when bulk-scale sampling combined the two facies, demonstrating the requirement of micro-scale sampling when identifying supercooling in basal ice facies. These findings indicate that sampling for isotopic compositions of ice facies frozen from supercooled water should be conducted at a scale that prevents the amalgamation of different facies to highlight a detailed isotopic signature. We conclude that micro-scale sampling is imperative to understanding and quantifying this subglacial process.
{"title":"Micro-Scale isotopic analysis of ice facies frozen from supercooled water","authors":"Connor J. Shiggins, M. Harris, P. G. Knight, C. Fogwill","doi":"10.1080/04353676.2020.1762364","DOIUrl":"https://doi.org/10.1080/04353676.2020.1762364","url":null,"abstract":"ABSTRACT Subglacial glaciohydraulic supercooling can form basal ice and affect glacier dynamics, sediment transfer and geomorphology. Whilst isotopic analysis (δ18O-δD) of basal ice has demonstrated the significance of supercooling, questions remain as to what extent the identification of supercooling depends on sampling resolution. We conducted laboratory experiments in which ice was frozen from supercooled water and sampled at a micro-scale (1.5 millilitre) to identify highly localized variations in isotopic compositions that might be lost in bulk-scale sampling. Three distinctive ice facies produced by the freezing process demonstrated diagnostic isotopic signatures that were distinguished when the facies were sampled independently. However, their respective isotopic signatures were lost when bulk-scale sampling combined the two facies, demonstrating the requirement of micro-scale sampling when identifying supercooling in basal ice facies. These findings indicate that sampling for isotopic compositions of ice facies frozen from supercooled water should be conducted at a scale that prevents the amalgamation of different facies to highlight a detailed isotopic signature. We conclude that micro-scale sampling is imperative to understanding and quantifying this subglacial process.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"33 1","pages":"104 - 117"},"PeriodicalIF":1.5,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83237706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/04353676.2020.1765578
W. Whalley
ABSTRACT Field observations, map analysis and the use of terrestrial and aerial photography and Google Earth show that the Gruben rock glacier, discussed in the literature since 1974, does contain a glacier ice core. Mapped as bare glacier ice at the time of the first map, about AD 1850, subsequent cover by debris from the surrounding cliffs has preserved what is now a slow-moving glacier core beneath a debris cover about 0.5 m thick. Formerly, the steeper and thicker glacier moved debris to the snout much more rapidly than at the present flow rates. The, adjacent, and once co-flowing, tongue of glacier ice was sparsely covered and has down-wasted substantially since the Little Ice Age (ca AD 1850) maximum. Surface down-wasting, surface lakes, ice exposures, and snout recession indicate that the rock glacier’s volume is reducing by wastage of the glacier ice core. This reduction in thickness and surface slope over the last 150 years is sufficient to explain all the observed phenomena in the Gruben basin and present-day low (<1 ma−1) rock glacier surface velocities. Further exposures of glacier ice in the rock glacier are expected with increasing ‘climatic warming’. These findings suggest that the ‘permafrost’ origin of rock glaciers should be re-evaluated.
{"title":"Gruben glacier and rock glacier, Wallis, Switzerland: glacier ice exposures and their interpretation","authors":"W. Whalley","doi":"10.1080/04353676.2020.1765578","DOIUrl":"https://doi.org/10.1080/04353676.2020.1765578","url":null,"abstract":"ABSTRACT Field observations, map analysis and the use of terrestrial and aerial photography and Google Earth show that the Gruben rock glacier, discussed in the literature since 1974, does contain a glacier ice core. Mapped as bare glacier ice at the time of the first map, about AD 1850, subsequent cover by debris from the surrounding cliffs has preserved what is now a slow-moving glacier core beneath a debris cover about 0.5 m thick. Formerly, the steeper and thicker glacier moved debris to the snout much more rapidly than at the present flow rates. The, adjacent, and once co-flowing, tongue of glacier ice was sparsely covered and has down-wasted substantially since the Little Ice Age (ca AD 1850) maximum. Surface down-wasting, surface lakes, ice exposures, and snout recession indicate that the rock glacier’s volume is reducing by wastage of the glacier ice core. This reduction in thickness and surface slope over the last 150 years is sufficient to explain all the observed phenomena in the Gruben basin and present-day low (<1 ma−1) rock glacier surface velocities. Further exposures of glacier ice in the rock glacier are expected with increasing ‘climatic warming’. These findings suggest that the ‘permafrost’ origin of rock glaciers should be re-evaluated.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"67 1","pages":"141 - 161"},"PeriodicalIF":1.5,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90950436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/04353676.2020.1761096
A. Law, Z. Robinson, Katie Szkornik, R. Waller
ABSTRACT Little is known about the ecological implications of high-magnitude, low frequency jökulhlaup events in proglacial systems. This study highlights how kettle lakes produced by jökulhlaups in proglacial areas create short-lived ecosystems and increase biodiversity. This research also demonstrates that as ice-margins retreat, creating new proglacial lakes and aquatic habitats, these sites may be increasingly important as sites of biogeochemical cycling and carbon fixing. Using diatoms from the base of former kettle hole lakes formed during the November 1996 jökulhlaup on Skeiðarársandur, south-east Iceland, we investigate the record of changing conditions of these lakes over their short (∼15 year) life span. Diatom assemblages were investigated in sediment sections up to 0.36m deep from the base of two kettle holes, and across a profile of surface sediments in one kettle hole. The diatom assemblages across all kettle holes are dominated by small benthic species (e.g. Achnanthes, Navicula, Nitzschia and Fragilaria spp.), with planktonic species (Cyclostephanos, Stephanodiscus spp.) present in only one kettle hole. The diatom assemblages are characterized by species with high nutrient and alkalinity optima. The variation in the diatom assemblages between different sedimentary units in the kettle holes’ basal stratigraphy reflect changes in the proportion of available habitat type (e.g. benthic, planktonic and littoral) resulting from changes in water levels, and changes in water chemistry relating to variations in sediment input (e.g. aeolian accumulation, slumping and re-working) and source of water (e.g. precipitation, ground water, snow melt). A conceptual model for typical kettle lake development in proglacial environments is also presented.
{"title":"Diatom assemblages from short-lived jökulhlaup-formed kettle lakes in a proglacial outwash plain, south-east Iceland","authors":"A. Law, Z. Robinson, Katie Szkornik, R. Waller","doi":"10.1080/04353676.2020.1761096","DOIUrl":"https://doi.org/10.1080/04353676.2020.1761096","url":null,"abstract":"ABSTRACT Little is known about the ecological implications of high-magnitude, low frequency jökulhlaup events in proglacial systems. This study highlights how kettle lakes produced by jökulhlaups in proglacial areas create short-lived ecosystems and increase biodiversity. This research also demonstrates that as ice-margins retreat, creating new proglacial lakes and aquatic habitats, these sites may be increasingly important as sites of biogeochemical cycling and carbon fixing. Using diatoms from the base of former kettle hole lakes formed during the November 1996 jökulhlaup on Skeiðarársandur, south-east Iceland, we investigate the record of changing conditions of these lakes over their short (∼15 year) life span. Diatom assemblages were investigated in sediment sections up to 0.36m deep from the base of two kettle holes, and across a profile of surface sediments in one kettle hole. The diatom assemblages across all kettle holes are dominated by small benthic species (e.g. Achnanthes, Navicula, Nitzschia and Fragilaria spp.), with planktonic species (Cyclostephanos, Stephanodiscus spp.) present in only one kettle hole. The diatom assemblages are characterized by species with high nutrient and alkalinity optima. The variation in the diatom assemblages between different sedimentary units in the kettle holes’ basal stratigraphy reflect changes in the proportion of available habitat type (e.g. benthic, planktonic and littoral) resulting from changes in water levels, and changes in water chemistry relating to variations in sediment input (e.g. aeolian accumulation, slumping and re-working) and source of water (e.g. precipitation, ground water, snow melt). A conceptual model for typical kettle lake development in proglacial environments is also presented.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"107 1","pages":"162 - 181"},"PeriodicalIF":1.5,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79566965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/04353676.2020.1744075
M. Y. Esper Angillieri, L. Perucca, Nicolás Vargas
ABSTRACT Numerous slides, rock falls and flows occur in the arid mountainous areas of northwestern Argentina. On 10 January 2017, torrential rain caused the acceleration of large-scale and slow-moving landslides mainly in the Los Filtros basin and it produces important damage in the Volcán village causing fatalities, dozens of evacuees and great economic losses, with the total destruction of buildings, services and infrastructure. However, in the two adjacent creek basins, the Coiruro basin to the north and Del Medio basin to the south, the effects were smaller. A morphometric analysis of these three adjacent basins was carried out in order to understand this catastrophic event and to explore its causes. The geological characteristics of the study basins are very favourable conditioning factors in landslide generation. Precambrian-age low grade metaclastics shatter in the frost climate of the higher mountains and poorly consolidated Quaternary deposits along the sides of the gully erode readily and become source material for landslides. Also, the area, shape, relief and slope of the basins would have been other key factors in the debris/mud flow generation in the Los Filtros creek basin. The Melton ratio number has been a key morphometric index to discriminate river basins susceptible to different types of flows. Finally, this study aims to increase knowledge of all the above-mentioned events in order to provide several methods of analysis for landslide prevention and control in adjacent basins whit different dynamics in the Central Andes.
{"title":"Spatial and temporal analysis of debris flow occurrence in three adjacent basins of the western margin of Grande River: Quebrada de Humahuaca, Jujuy, Argentina","authors":"M. Y. Esper Angillieri, L. Perucca, Nicolás Vargas","doi":"10.1080/04353676.2020.1744075","DOIUrl":"https://doi.org/10.1080/04353676.2020.1744075","url":null,"abstract":"ABSTRACT Numerous slides, rock falls and flows occur in the arid mountainous areas of northwestern Argentina. On 10 January 2017, torrential rain caused the acceleration of large-scale and slow-moving landslides mainly in the Los Filtros basin and it produces important damage in the Volcán village causing fatalities, dozens of evacuees and great economic losses, with the total destruction of buildings, services and infrastructure. However, in the two adjacent creek basins, the Coiruro basin to the north and Del Medio basin to the south, the effects were smaller. A morphometric analysis of these three adjacent basins was carried out in order to understand this catastrophic event and to explore its causes. The geological characteristics of the study basins are very favourable conditioning factors in landslide generation. Precambrian-age low grade metaclastics shatter in the frost climate of the higher mountains and poorly consolidated Quaternary deposits along the sides of the gully erode readily and become source material for landslides. Also, the area, shape, relief and slope of the basins would have been other key factors in the debris/mud flow generation in the Los Filtros creek basin. The Melton ratio number has been a key morphometric index to discriminate river basins susceptible to different types of flows. Finally, this study aims to increase knowledge of all the above-mentioned events in order to provide several methods of analysis for landslide prevention and control in adjacent basins whit different dynamics in the Central Andes.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"11 1","pages":"103 - 83"},"PeriodicalIF":1.5,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86524082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/04353676.2020.1762365
J. Matthews, S. Haselberger, Jennifer L. Hill, G. Owen, S. Winkler, J. Hiemstra, Helen Hallang
ABSTRACT Eleven snow-avalanche boulder fans were dated from two high-alpine sites in Jotunheimen using Schmidt-hammer exposure-age dating (SHD) and lichenometry. Average exposure ages of the surface boulders ranged from 2285 ± 725 to 7445 ± 1020 years and demonstrate the potential of SHD for dating active landforms and diachronous surfaces. Application of GIS-based morphometric analyses showed that the volume of rock material within 10 of the fans is accounted for by 16–68% of the combined volume of their respective bedrock chutes and transport zones. It is inferred that the fans were deposited entirely within the Holocene, mainly within the early- to mid Holocene, by frequent avalanches carrying very small debris loads. Relatively small transport-zone volumes are consistent with avalanches of low erosivity. Excess chute volumes appear to represent subaerial erosion in the Younger Dryas and possibly earlier. Debris supply to the fans was likely enhanced by early-Holocene paraglacial processes following deglaciation, and by later permafrost degradation associated with the mid-Holocene Thermal Maximum. The latter, together with the youngest SHD age from one of the fans, may presage a similar increase in geomorphic activity in response to current warming trends.
{"title":"Snow-avalanche boulder fans in Jotunheimen, southern Norway: Schmidt-hammer exposure-age dating, geomorphometrics, dynamics and evolution","authors":"J. Matthews, S. Haselberger, Jennifer L. Hill, G. Owen, S. Winkler, J. Hiemstra, Helen Hallang","doi":"10.1080/04353676.2020.1762365","DOIUrl":"https://doi.org/10.1080/04353676.2020.1762365","url":null,"abstract":"ABSTRACT Eleven snow-avalanche boulder fans were dated from two high-alpine sites in Jotunheimen using Schmidt-hammer exposure-age dating (SHD) and lichenometry. Average exposure ages of the surface boulders ranged from 2285 ± 725 to 7445 ± 1020 years and demonstrate the potential of SHD for dating active landforms and diachronous surfaces. Application of GIS-based morphometric analyses showed that the volume of rock material within 10 of the fans is accounted for by 16–68% of the combined volume of their respective bedrock chutes and transport zones. It is inferred that the fans were deposited entirely within the Holocene, mainly within the early- to mid Holocene, by frequent avalanches carrying very small debris loads. Relatively small transport-zone volumes are consistent with avalanches of low erosivity. Excess chute volumes appear to represent subaerial erosion in the Younger Dryas and possibly earlier. Debris supply to the fans was likely enhanced by early-Holocene paraglacial processes following deglaciation, and by later permafrost degradation associated with the mid-Holocene Thermal Maximum. The latter, together with the youngest SHD age from one of the fans, may presage a similar increase in geomorphic activity in response to current warming trends.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"36 1","pages":"118 - 140"},"PeriodicalIF":1.5,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74709588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-02DOI: 10.1080/04353676.2019.1704488
J. Boelhouwers, C. Andersson, Rikard Berg, Razia Asad Kandastar, Alfons Sjöman, Elin Vainionpää Lindgren
ABSTRACT The known post-glacial isostatic land rise rates at Fårö Island, Central Baltic Sea, allowed for the reliable estimation of frost weathering rates of limestone clasts along five beach profiles. Weathering rates measured by clast dimension change were quantified over periods ranging between 640 and 2090 years. While the deposited beach materials at each profile have varying lithostratigraphic compositions these attributes appear to have no direct influence on the long-term comminution rates. Mean clast size of initially deposited beach materials is suggested to be primarily a function of local wave energy and sourced from local rock platforms. Field observations, climate data and literature point to the beach materials in the upper 10–20 cm being fractured under an active diurnal to short-term frost environment that has persisted over the past 1000–2000 years. Pore water freezing by 9% volumetric expansion and the development of pore water expulsion and hydrofracture is suggested to increase pore volume and pore interconnectedness over time and facilitate ice segregation growth. Observed modes of clast fracture, bursting, flaking and granular disaggregation suggest different frost weathering mechanisms to operate on different limestone lithologies. Long term rates of break down appear however not differentiated by limestone composition.
{"title":"Long-term frost weathering rates of limestone beach clasts, Fårö Island, Central Baltic Sea","authors":"J. Boelhouwers, C. Andersson, Rikard Berg, Razia Asad Kandastar, Alfons Sjöman, Elin Vainionpää Lindgren","doi":"10.1080/04353676.2019.1704488","DOIUrl":"https://doi.org/10.1080/04353676.2019.1704488","url":null,"abstract":"ABSTRACT The known post-glacial isostatic land rise rates at Fårö Island, Central Baltic Sea, allowed for the reliable estimation of frost weathering rates of limestone clasts along five beach profiles. Weathering rates measured by clast dimension change were quantified over periods ranging between 640 and 2090 years. While the deposited beach materials at each profile have varying lithostratigraphic compositions these attributes appear to have no direct influence on the long-term comminution rates. Mean clast size of initially deposited beach materials is suggested to be primarily a function of local wave energy and sourced from local rock platforms. Field observations, climate data and literature point to the beach materials in the upper 10–20 cm being fractured under an active diurnal to short-term frost environment that has persisted over the past 1000–2000 years. Pore water freezing by 9% volumetric expansion and the development of pore water expulsion and hydrofracture is suggested to increase pore volume and pore interconnectedness over time and facilitate ice segregation growth. Observed modes of clast fracture, bursting, flaking and granular disaggregation suggest different frost weathering mechanisms to operate on different limestone lithologies. Long term rates of break down appear however not differentiated by limestone composition.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"15 1","pages":"12 - 32"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79598897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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