1,721,005 research outputs found
Scale dependence of hydrological effects from different climatic conditions on glacierized catchments
Full text linkThe high altitude environments are particularly sensitive to climate change and very rapid and intense effects are affecting the Alpine cryosphere. Knowledge of the hydrological responses of high-altitude watershed is critical to manage water resources, especially in the context of current climate change, resulting in a lower percentage of solid precipitation, temporal redistribution and quantitative variations in precipitation inputs, higher temperatures, and more persistent drought conditions during the summer. Although the remaining glacial masses are still able to secure sufficient water supplies, the rate of reduction of the glaciers, however, is now very rapid. Mountain glaciers have generally experienced worldwide retreat since the second half of XIX Century, and for example in the Alps they lost about two/thirds of the initial area, with area loss rates accelerating since 2003. At this pace, the hydrological buffering effect of the glaciers will run out quickly. Several years in the last decades, which have been particularly warm and dry, have shown that glaciers can compensate scarce rainfall with a significant contribution to the runoff of rather large basins, especially in summer.
The aim of this work was to understand how different climatic and glacier cover conditions can modify the hydrological response of glacierized catchments, and to analyze the scale dependency of the hydrological response and the resulting impacts on fresh water availability.
The investigations were carried out in the Noce catchment, a 1050 km2 watershed located in the Eastern Italian Alps, and in three sub-catchments of the same basin, with area ranging from 8 to 385 km2 and different percent glacierization. Valuable information on past and current evolution of climate and glaciers exist in this study area. In particular, precious data series of high-altitude meteorological and hydrometric data, reconstructions of glacier fluctuations since the Little Ice Age, and measurements of glacier mass balance were available. Based on this availability, and considering the high uncertainties affecting model studies that use future projections of climate and glaciers, we decided to do a sensitivity analysis based on past observations. This approach has the advantage of analyzing the sensitivity of the glacio-hydrological system of the study area under actually observed climatic and glacier cover conditions, likely reducing the main source of error caused by model approaches based on future projections. Moreover using real observations has the potential of increasing the internal consistency of the glacio-hydrological model employed in this sensitivity analysis, during calibration and validation. A drawback of this method is that it does not take into consideration future change in climate and glacier cover. For this reason, we analyzed also a condition with complete absence of glaciers, and recent ‘extreme’ years, like 2003, that has been frequently referred to as a possible example of future climatic conditions during summer in the Alps.
The results of this study confirm previous research that indicate a progressive transition from a glacial to a nival hydrological regime in the analyzed catchments, with a tendency to a strong decrease in runoff after the seasonal snow has melted, in the second half of summer. The runoff peak tends to shift from mid- to early summer. Different glacier cover scenarios (LIA, current and absence of glaciers) have highest impacts in August runoff, during periods of glacier wastage as in the 1940s and in the 2000s, and in the smaller catchments with high percent glacierization. Compared to the absence of glaciers, current glaciers still ensure higher runoff during summer, in all climatic conditions considered. However, this glacier damping effect is largely decreased if compared to the LIA conditions, and this decrease is directly related to catchment area. If smaller and highly glacierized catchment still preserves ~50% of the initial damping effect in August, the larger catchments keep only 25-30% of it. The glacier contribution to late summer runoff decreases obviously from headwater to lower and larger catchments. However, the decreasing rate tends to flatten for catchment area larger than 80 km2, and for the larger analyzed catchment it still reaches 26%. Most importantly, the current glacier contribution to late summer runoff in the larger catchment reaches ~60% in extremely warm and dry summers, like in 2003. However, increased runoff due to glacier wastage in 2003 occurred only in the headwater and most glacierized catchment, whereas using the LIA glacier cover would have ensured increased runoff in all analyzed catchments. This suggests that the expected peak in runoff under warming climate, attributable to glacier melt, has already passed in the study area
Air temperature variability over three glaciers in the Ortles-Cevedale (Italian Alps): effects of glacier disintegration, intercomparison of calculation methods, and impacts on mass balance modeling
No full textSpatio-temporal variability in tracer signature of snow, ice and stream water in a glacierized catchment of the Ortles-Cevedale (Eastern Italian Alps)
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Analysing the climatic sensitivity of glacierized alpine watersheds using historic hydro-meteorological observations
Full text linkSpatio-temporal variability in tracer signature of snow, ice and stream water in a glacierized catchment of the Ortles-Cevedale (Eastern Italian Alps)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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