1,720,972 research outputs found
Future perspectives of run-of-the-river hydropower and the impact of glaciers’ shrinkage: The case of Italian Alps
No full textWe assess the impacts of nine climate-change scenarios on the hydrological regime and on hydropower production of forty-two glacierized basins across the Italian Alps, assumed exemplary of similar systems in other glacierized contexts. Each of these basins includes one (or more) hydropower plant, here treated as a run-of-the-river system. We implemented a semi-distributed hydrologic model that divides each basin in elevation bands and reconstructs orographic effects on both precipitation and temperature. The nine climate-change scenarios quantify the individual and combined effects of an increase in temperature and a change in liquid-solid phase partition. The simulation horizon is 2016–2065. Thus, we avoided long-term scenarios and worked at short-medium range to maximize the relevance of this work for decision makers. Our results predict a decline of about −30% in average summer runoff across all basins compared to present. Because most of this decrease in runoff occurs during high-flow periods when the run-of-the-river capacity of these plants is exceeded, this result translates into a median decrease of about −3% in hydropower production for run-of-the-river systems through 2065, across all the basins and all scenarios. The predominant cause of this decline is glacier shrinkage, whereas different temperature or precipitation trends plays a marginal role. Run-of-the-river hydropower production in basins where the current glacier coverage is less than 10% of total area is particularly robust to climate change
Water-energy nexus for an Italian storage hydropower plant under multiple drivers
No full textClimate change has repercussions on the management of water resources. Particularly, changes in precipitation and temperature impact hydropower generation and revenue by affecting seasonal electricity prices and streamflow. This issue exemplifies the impact of climate change on the water-energy-nexus, which has raised serious concern. This paper investigates the impact of climate change on hydropower with a multidisciplinary approach. A holistic perspective should be favored as the issue is complex, consequently, we chose to investigate a specific case study in Italy. It allows grasping the details, which matters in mountainous area. We integrated a hydrological model, hydropower management model, nine climate scenarios, and five electricity scenarios for a specific storage hydropower plant. Independently from the scenarios, the results show a glacier volume shrinkage upward of 40% by 2031 and minimum of 50% by 2046. The reservoir mitigates losses of revenue that reach 8% in the worst case, however, are lower compared with run-of-the-river configuration. Changes in price seasonality amplitude also determine modifications in revenues, while temporal shifts appear to be ineffective. For run-of-the-river, any variation in hydrological cycle immediately translates into revenue. Comparing the results of all future scenarios with the base scenario, it can be concluded that an increase in temperature will slightly improve the performances of hydropower
Hydropower future: Between climate change, renewable deployment, carbon and fuel prices
No full textHydropower represents an interesting technology: affordable, renewable, and flexible. However, it must cope with climate changes and new energy policies that jeopardize its future. A smooth transition to sustainability requires decision makers to assess the future perspectives of hydropower: about its future revenue and related uncertainty. This investigation requires a multidisciplinary approach as both streamflow and energy mix will evolve. We simulated future streamflow based on eight climate scenarios using a semi-distributed hydrological model for our case study, the Tremorgio hydropower plant located in southern Switzerland. Next, using a hydropower management model we generated income according to these streamflows and twenty-eight electricity price scenarios. Our results indicate that climate change will modify the seasonality of inflows and volumes exploitable for hydropower generation. However, adaptive strategies in the management of reservoirs could minimize revenue losses/maximize revenue gains. In addition, most market scenarios project an increase in revenues, except in the case of high wind and solar energy penetration. Markets do not provide the right incentive, since the deployment of intermittent energy would benefit from more flexible hydropower
Past, Present and Future Perspectives of Seasonal Prediction of Indian Summer Monsoon Rainfall: A Review
No full textThis paper presents a detailed review and discussion on the long-range forecast (LRF) of Indian summer monsoon rainfall (ISMR), its present status, problems, and perspectives with an emphasis on the Indian meteorological department (IMD) operational forecasting methods and its forecasts. Verifications of IMD LRF for 1924-1987 revealed a success rate of nearly 64%. IMD operational LRF skills (correlation coefficient) during the period 1988-2020 were found as 0.25 and 0.34 for the 1st -stage (April) and 2nd -stage (June), respectively. From 1988 to 2020 (33-years), 21-years of predictions were predicted out of the confidence band (±4%LRF). Out of these 21-years, 18-years were individual or co-occurring El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) event years. It indicates that IMD operational models have failed to capture ENSO and IOD phenomenon effects in their predictions considerably, despite the developing stage of ENSO and IOD events during the monsoon season. Moderate success and limitations of statistical models of IMD lead to the launching of the Monsoon mission (MM) in 2012 to use the dynamical prediction system by using the climate forecast system. Within a span of 7-years, MM has brought the skill of ISMR prediction to 0.71, which is above the older potentially predictable limit estimate of 0.65. Overall, in the last century, enormous progress has been made on the LRF of the ISMR. The accurate capturing of the ENSO and IOD phenomenon, incorporation of non-stationarity components in the predictors, improvements in the model microphysics and initial conditions could improve prediction skills
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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