1,721,116 research outputs found
The use of remotely sensed land cover to derive floodplain friction coefficients for flood inundation modelling
No full textRemotely sensed land cover was used to generate spatially-distributed friction coefficients for use in a two-dimensional model
of flood inundation. Such models are at the forefront of research into the prediction of river flooding. Standard practice,
however, is to use single (static) friction coefficients on both the channel and floodplain, which are varied in a calibration
procedure to provide a “best fit” to a known inundation extent. Spatially-distributed friction provides a physically grounded
estimate of friction that does not require fitting to a known inundation extent, but which can be fitted if desired. Remote
sensing offers the opportunity to map these friction coefficients relatively straightforwardly and for low cost. Inundation was
predicted using the LISFLOOD-FP model for a reach on the River Nene, UK. Friction coefficients were produced from land
cover predicted from Landsat TM imagery using both ML and fuzzy c-means classifiction. The elevetion data used were
from combined contour and differential global positioning system (GPS) elevation data. Predicted inundation using spatiallydistributed
and static friction were compared. Spatially-distributed friction had the greatest effect on the timing of flood
inundation, but a small effect on predicted inundation extent. The results indicate that spatially-distributed friction should be
considered where the timing of initial flooding (e.g. for early warning) is important
Sensitivity analysis of a flood inundation model to spatially-distributed friction coefficients obtained using land cover classification of Landsat TM imagery
No full textIn this paper, land cover was predicted from
Landsat TM imagery and used to generate spatially-distributed
friction coefficients. Flood inundation was then predicted using
the raster-based model LISFLOOD-FP, based on friction and
three different elevation models. Sensitivity of LISFLOOD-FP
to spatially-distributed friction was assessed. It was found that
effect of friction on the ?ood wave is small when compared to the
underlying elevation, but is greatest during the recession phase
of the hydrograph
Prediction uncertainty in floodplain elevation and its effect on flood inundation modelling
No full textThe use of elevation data in flood inundation modelling: a comparison of ERS interferometric SAR and combined contour and differential GPS data
No full textThree internationally-available elevation models were assessed for suitability for use in the prediction of flood inundation. The elevation data were selected because they represent data which may be available in data-poor developing countries. These were a contour data set, a remotely sensed dataset (interferometric SAR) and a dataset which may be obtained rapidly through a differential global positioning system (DGPS) survey. The latter dataset was known to have much less uncertainty than the contour dataset and was, therefore, accepted as a benchmark against which to test the other two. Each dataset was used to predict flood inundation for an event in the United Kingdom in 1998 using the two-dimensional model LISFLOOD-FP. The contour dataset was different in spatial character (overly smooth) to the DGPS dataset and resulted in substantial differences in the timing and extent of flood inundation. The interferometric SAR dataset was also different in spatial character (overly rough) to the DGPS dataset although the differences in the timing and extent of flooding were not as great as for the contour dataset. However, results demonstrate potential problems with the use of satellite remotely sensed topographic data in flood hazard assessment over small areas
Assessing the effect of uncertainty in spatially distributed friction coefficients on flood inundation modelling
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Prediction uncertainty in elevation and it’s effect on flood inundation modelling, GeoComputation
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