1,722,516 research outputs found
Channel morphology evolution and bedload transport of the Reno river in northern Italy
No full textThe Reno R., as many other Italian rivers, has been significantly affected by man activity since Romans time, but in the last decades significant land use changes in the headwater, extensive bed material mining, dams construction, torrent-control works and large fluids extraction from the underground caused important channel morphology and sediment fluxes changes.
To better understand such morphological changes and their causes, the hydraulic geometry data of several cross sections and the longitudinal profile data of the Reno river, surveyed at different times, were analysed emphasizing a dramatic streambed incision that took place between 1950s and 1980s, with a volume of sediment lost of about 18 x106 m3.
At the same time a field campaign was started in 2003 collecting representative bed material samples and sediment transport measurements with Helley-Smith bedload sampler to assess the present river dynamics and evolution.
Bedload transport rate resulted very low also during floods larger than bankfull stage and even those equations renown in the literature to underpredict bedload transport overestimate the sediment transport of the Reno R. Among the equations used those predicting transport rates closer to the actual surveyed values are modified Meyer-Peter & Muller equation
The river transport capacity always resulted by far larger than sediment supply and no significant relation was found between flow parameters and the bedload transport rates measured. The occurrence of cyclic peaks and lows of bedload rate and a clear seasonality were as well.
Sediment deficit of the Reno river system results from many factors including an increase in forest cover, presence of dams for agricultural and hydroelectric purposes, engineering works on the watershed and on the river channel, large bed material exploitation and likely a decrease in flood frequency
HUMAN IMPACT ON CHANNEL MORPHOLOGY AND SEDIMENT FLUX OF THE RENO RIVER IN NORTHERN ITALY
No full textThe Reno River is the eleventh largest river in Italy. It has been extensively affected by man activity for a very long span of time. The first relevant impacts date back to the Romans time and were reiterated with more or less intensity until present. During the last five centuries, the lowland portion of the river was subjected to remarkable channel modifications, diversion, levee construction, reclamation of the this portion of the Po plain. In the recent decades, mainly after World War II, significant changes in land use and management in the mountain portion of the catchment, extensive exploitation of the streambed material, the construction of a sluice gate for irrigation purposes a few kilometres upstream of the river mouth and large withdrawal of fluids from the underground caused important channel and sediment budget changes. Three main effects of such human impacts are evident: a remarkable streambed degradation (as much as 5 m during the last 60 years), the reduction to a hard to detect quantity of bedload flux and, consequently, a worrying beach erosion that is rapidly retreating along a vast portion of the Adriatic coast fed by the Reno R., that is an important tourist resort and economic resource for the region. In order to understand such morphological changes, their causes and, possibly, to envisage some solutions a field campaign of sediment transport measurement was started in 2003 and it is still in progress. To get a clearer picture of the present situation also bed material samples were taken along the alluvial plain, lower reach of the Reno R. and the hydraulic geometry data of hundreds of cross sections, surveyed at different times, were analysed to quantify the streambed degradation and the channel morphology changes. Bedload transport rate, in particular, resulted very low also during floods larger than bankfull and even those equations renown in the literature to underpredict bedload transport overestimate the sediment transport of the Reno R.. The river transport capacity always resulted by far larger than sediment supply. However, no significant relation was found between the flow main hydraulic parameters and the bedload transport rates measured. The occurrence of cyclic peaks and lows of bedload rate suggests the transit of dune bedforms across the measuring site. The data gathered indicate that the only reliable way to assess bed material flux in a river with an impoverished sediment supply and transport is through the analysis of dune morphology and migration rate, though seasonal variations in sediment supply may require to take into account also this aspect in adapting such a methodology
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
Large wood and flash floods: evidence from the 2007 event in the Davča basin (Slovenia)Monitoring, Simulation, Prevention and Remediation of Dense Debris Flows II
No full textVariations 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
