1,720,979 research outputs found
Inferring the spectral properties of river flows for hydrological model calibration in ungauged catchments
No full textHydrological extremes: controls, spatial & temporal variability and regional patterns (Session HS36, EGU General Assembly 2007)
No full textFloods and droughts are the major weather related hydrological disasters and recent events have demonstrated Europe’s continuing exposure to these natural hazards. High and low flows and associated floods and droughts are natural phenomena caused by meteorological anomalies and modified by the physical characteristics of catchments. The knowledge about the quantity, timing and risk of extreme discharges during floods and droughts is the basic requirement for a broad range of purposes in hydrology and water resources management. This knowledge has ideally to be based on the understanding the controls of the genesis of hydrological extremes (like the importance of landscape heterogeneities, threshold processes, scaling issues), finding appropriate ways how to characterize them (spatial and temporal variability, regional patterns) and designing reliable methods of predicting.
Hydrological models based on physical concepts, statistical or regional approaches are used to define relationships between extreme flows, their characteristics and basin properties in order to predict characteristics of extremes at gauged and ungauged sites. The knowledge of the dominant processes of a study area is essential to pursue this task, and there is consensus among modellers that the parsimony of models is one important factor of predictive performance.
The main objectives of this session are (a) to foster the understanding of the main governing processes of floods and droughts, (b) to discuss modeling approaches and concepts how to include process understanding in predictive models, (c) to shed light on the regional characteristics and spatial patterns of floods and droughts and the processes that give rise to such patterns including climate forcing, extreme precipitation and catchment response, (d) to present methods for estimating and/or predicting floods, droughts and low flows at a regional scale as well as regional methods for making predictions at the local scale, (e) to learn from practical applications of such models, (f) to profit from the similarity and differences of modeling concepts for both extremes.
Specifically, papers are solicited that address one or more of the following questions:
- what are the important mechanisms producing regional extremes, and how the use of diverse hydrological methods can contribute to highlighting the governing processes
- what is the role of climatic forcing and catchment properties in the regional distribution of extremes,
- which hydro-meteorological and catchment characteristics and indices can be used to describe regional patterns of extremes,
- how do anthropogenic impacts and different land use patterns affect the spatial patterns of regional extremes,
- how effective and reliable are the multivariate statistical techniques (e.g., cluster analysis, artificial neural networks, copulas, etc.) for identification of watersheds with similar dominant hydrological characteristics
The scope of the session includes both general methodological contributions and case studies in different regions
Analytic probability distributions for snow-dominated streamflows
Full text linkWe propose a novel analytical description of the streamflow probability distribution functions (pdfs) in Alpine catchments characterized by pronounced, snow-dominated winter low flows. Knowledge about such hydrological regimes is crucial for water resources management in mountain environments and the related wide range of socio-economic, environmental and ecological services. We use a stochastic framework, generalizing that employed by Botter et al. (2007b), to link precipitation (rain and snow) and streamflow dynamics. The effect of snow dynamics on the flow regime is specifically included by incorporating the temporary disconnection of high-elevation areas that experience freezing conditions over the entire winter season, and the delay produced on streamflow formation by the temporary accumulation (and later melting) of snow at lower elevations. The novel analytical model employs four parameters that can be directly estimated from observed discharge, precipitation and air temperatures, and one calibration parameter (the elevation threshold z delimiting catchment areas with a permanent seasonal snow cover that is nonresponsive during winter owing to snow accumulation without melt). We test the developed model for 14 catchments with contrasting hydroclimatic conditions, located in the Swiss and the Italian Alps. Overall, the proposed analytic model reproduces the observed streamflow pdfs remarkably well. Exceptions exist, though, and the possible origin of deviations between observed and modeled pdfs are discussed. We suggest that our approach marks a progress toward the general statistical characterization of catchment streamflow variability.ECH
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
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
- …
