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Summer rainstorm associated with a debris flow in the Amarilla gully affecting the international Agua Negra Pass (30°20′S), Argentina Texto completo
2017
Lauro, Carolina | Moreiras, StellaM. | Junquera, Sebastian | Vergara, Ivan | Toural, Rafael | Wolf, Johannes | Tutzer, Ruben
The Central-West region of Argentina was seriously affected by a series of convective summer storms on January–February of 2013 generating many debris flows and rockfall in the Central Andes mountain regions. In particular, the unreported 8th February event caused the sad death of a 10-year-old child being completely ignored by society and local authorities. Despite this, meteorological conditions associated with this event and further episodes were rarely measured and determined mainly due to scarce meteorological stations in Andean mountain areas. In this paper, meteorological data from CMORPH algorithm and measurements of surrounding gauges were analyzed for estimating the triggering precipitation value of this event. As well, the particular debris flow channeled into the main branch of the Amarilla gully in the Agua Negra valley was geomorphologically described. The amount of precipitation associated with this debris flow was 5.5 and 13.2 mm accumulated previous to the event. This violent debris flow was generated in a talus zone in a periglacial environment located just below a covered rock glacier. However, the influence of the permafrost thawing in this process is not feasible. The altitude of the 0 °C isotherm was lower during the previous days of the event, and no monitoring on permafrost is available for this area. The volume of removed mass was estimated in 5 × 10⁴ m³, and the mean velocity was 35 km/h. Boulders of 4 m diameter were found in the source area, while the deposit is up to 75% sandy with clasts that hardly exceed 10 cm in the alluvial fan distal part. Herein the main objective is to advice about the probable catastrophic impact of similar events in the future. These findings could be useful for hazard remediation, mitigation, and prevention plans for the Agua Negra international pass under construction.
Mostrar más [+] Menos [-]Groundwater occurrence in cold environments: examples from Nunavik, Canada | Occurrence des eaux souterraines dans des environnements froids: exemples du Nunavik, Canada Ocurrencia de agua subterránea en ambientes fríos: ejemplos de Nunavik, Canadá 寒冷环境中地下水的赋存状况:加拿大努那维克的实例 Ocorrência de água subterrânea em ambientes frios: exemplos de Nunavik, Canadá Texto completo
2016
Lemieux, Jean-Michel | Fortier, Richard | Talbot-Poulin, Marie-Catherine | Molson, John | Therrien, René | Ouellet, Michel | Banville, David | Cochand, Marion | Murray, Renaud
Water availability and management issues related to the supply of drinking water in northern communities are problematic in Canada. While rivers and lakes are abundant, they are vulnerable to contamination and may become dry in winter due to freezing. Groundwater can often provide a more secure and sustainable water source, however its availability is limited in northern Canada due to the presence of permafrost. Moreover, the exploitation of northern aquifers poses a dual challenge of identifying not only permafrost-free areas, but also permeable areas which will allow groundwater recharge and exploitation. Suitable aquifers are not as common in northern Canada since the shallow subsurface is mostly composed of low-permeability crystalline rocks or unconsolidated sediments of glacial origin that are highly heterogeneous. In order to investigate groundwater occurrence and associated geological contexts in Nunavik (northern Quebec, Canada), along with exploring how these resources will evolve in response to climate change, field and compilation work were conducted in the surroundings of the four villages of Salluit, Kuujjuaq, Umiujaq and Whapmagoostui-Kuujjuarapik. These villages are located in different permafrost zones, ranging from continuous to discontinuous, as well as in different geological environments. It was found that despite the ubiquitous presence of permafrost, unfrozen aquifers could be identified, which suggests that groundwater may be available as a source of drinking water for small communities. Expected climate change, with predicted permafrost thawing and increases in temperature and precipitation, should enhance groundwater availability and may contribute to a more secure source of drinking water for northern communities.
Mostrar más [+] Menos [-]Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments | Utilisation des caractéristiques de l’écoulement superficiel pour explorer la fonte du pergélisol sur des bassins versants de la Suède du Nord Uso de las características del flujo de una corriente para explorar el deshielo del permafrost en cuencas suecas nórdicas 利用河川径流特征探讨瑞典北部流域永久冻土的融化 Uso das características de escoamento de cursos de água para exploração do degelo do permafrost em bacias hidrográficas no norte da Suécia Texto completo
2013
Sjöberg, Ylva | Frampton, Andrew | Lyon, SteveW.
The recent and rapid warming of the Arctic leads to thawing of permafrost, which influences and changes subsurface water-flow systems in such landscapes. This study explores the utility of catchments as “sentinels of change” by considering long-term discharge data from 17 stations on unregulated rivers in northern Sweden and analyzing trends in annual minimum discharge and recession flow characteristics. For the catchments considered, the annual minimum discharge has increased significantly (based on the Mann Kendall test at a 95 % confidence level) in nine of the catchments and decreased significantly in one catchment. Considering changes in recession-flow characteristics, seven catchments showed significant trends consistent with permafrost thawing while two catchments showed significant trends in the opposite direction. These results are mechanistically consistent with generic physically based modeling studies and the geological setting, as the catchments considered span the spatial limit of permafrost extent. This study illuminates the potential for using hydrologic observations to monitor changes in catchment-scale permafrost. Further, this opens the door for research to isolate the mechanisms behind the different trends observed and to gauge their ability to reflect actual permafrost conditions at the catchment scale.
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