1,721,205 research outputs found
Selecting the appropriate hydraulic model structure using low-resolution satellite imagery
No full textThis study aims at investigating the value added by an explicit representation of floodplain processes in
hydraulic models, by comparing the results of a pure 1D model to the ones of an integrated 1D–2D
model. The analysis is performed on a 96 km reach of the River Po (Italy). For this test site, two different
model structures (1D and 1D–2D) are implemented and compared. The models are first calibrated
using high water marks of a high magnitude event and then validated by means of a coarse resolution
space-borne flood extent map of a low-magnitude event. The explicit inclusion of 2D features strongly
improves the performance of the model, both in terms of accuracy and robustness. The possible causes
of this behaviour are investigated and some statements are drawn based on the analysis of the features
of the two flood events. Some general conclusions on the effect of the choice between 1D and 2D models
arise from the analysis of the calibration–validation procedure. In this context a new measure of fit
is proposed, to be used if binary (wet/dry) observations are available and is proven to be able to better
distinguish among different sets of model parameters. Lastly, the study also shows the ability of timely
low resolution satellite imagery to assist the selection of the most appropriate hydraulic model
structure
Can uncertainty in flood hazard estimation be reduced by using high detailed topographic data for floodplain modelling?
No full textFloods are considered the most frequent natural disaster world-wide and may have serious socio economic impacts in a community. In order to accomplish flood risk mitigation, flood risk analysis and assessment are required to provide information on current or future flood hazard and risks. Hazard and risk maps involve different data, expertise and effort, depending also on the end-users. More or less advanced deterministic approaches can be used, but intuitively probabilistic approaches seem to be more correct and suited for modelling flood inundation given typical uncertainties. Two very important matters remain open for research: the calibration of hydraulic models (oriented towards the estimation of effective roughness parameters) and the uncertainties (e.g. related to data, model structure and parameterisation) affecting flood hazard mapping results.
Here, we test the ability of high resolution topographic data to reduce the uncertainty in probabilistic flood inundation maps for two hydraulic models: a two-dimensional hyperbolic finite element model and a recently developed version of the LISFLOOD-FP model which solves a reduced form of the full shallow water equations in a highly efficient manner. These models are applied to the Imera River basin in Sicily using both high and low resolution topographic data sets and probabilistic flood inundation maps accounting given uncertainty in the observed inflow hydrograph to the reach constructed for each model/terrain data combination. Through a comparison of the resulting hazard maps, the influence of topographic data on probabilistic flood mapping will be shown
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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