1,721,012 research outputs found
Steady-state flow toward a pumping well: numerical validation of existing solutions and inference of the geostatistical model of spatial variability
No full textAn Analytical Framework for Risk Evaluation and Design of Infiltration Basins for Managed Aquifer Recharge
No full textManaged Aquifer Recharge (MAR) plays an important role in improving and supplementing groundwater storage. Many natural factors, ranging from climatic conditions to soil characteristics, can impact the efficiency of an infiltration basin. Other factors, such as engineered variables, will also influence the basin performance and the risks associated with groundwater contamination. The latter depends on the interplay between the hydraulic characteristics of the system and the soil and solute properties. The design of infiltration basins has been performed so far with the main objective of mitigating the tendency of the basin to reduce the infiltration rate with time due to clogging of the basin's bottom. Less attention has been paid to the risk of groundwater contamination by the infiltrating water. To understand the complex interplay between natural and engineering parameters on MAR efficiency and the contamination risk, we propose a risk-oriented analytical framework. The framework allows to investigate the interplay between soil parameters, engineering design and climatic factors on the efficiency of an infiltration basin. Our framework relies on novel analytical solutions that relates the geometrical and hydrological features of the infiltration basin to its efficiency and groundwater contamination risk. The solutions incorporates the randomness associated with inflows (precipitation) and soil properties. We explore the trade-off between efficiency and the risk of contamination and delineate a design procedure that balances these two opposing needs. Although the framework relies on simplifying assumptions, it provides a computationally efficient manner to obtain physical insights and relate model input parameters to decision making
On the use of spatially distributed, time-lapse microgravity surveys to inform hydrological modeling
No full textOn the Lagrangian formulations of reactive solute transport in the hydrologic response
No full textWe address Lagrangian dispersion of reactive solutes in the framework of the formulation of transport by travel time distributions, specifically aiming at models of basin-scale, nonpoint transport applicable to complex geomorphological settings. We revisit existing exact solutions of the reactive transport problem derived in the convective stochastic framework and extend them to the case of transport of mass arbitrarily distributed (in time and space) within the immobile phase, a situation which is arguably suited to better describe nonpoint source solute transport driven by the hydrologic response. The initial conditions and, particularly, the mass initially stored in immobile rather than mobile phases bear a pronounced effect on the spatial and temporal moments of the solute plume. We also show that in many nonpoint source cases of interest (typically when heterogeneous conditions prevail) a simpler model of reaction kinetics, where spatial gradients in the immobile concentration are neglected, does well. Such a class of models, termed mass response functions, is known from the literature and has the property, beside being simplified in the mass exchange terms, of embedding unsteady flow forcing of the type typically employed in the theory of the hydrologic response. Thus, in the range of cases where the well-mixed assumption proves meaningful, we suggest a natural extension of current geomorphological models of the hydrologic response to generic transport phenomena
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
Analysis of high streamflow extremes in climate change studies: how do we calibrate hydrological models?
No full textAbstract. Climate change impact studies on hydrological extremes
often rely on hydrological models with parameters inferred through
calibration procedures using observed meteorological data as input forcing.
We show that this procedure can lead to a biased evaluation of the
probability distribution of high streamflow extremes when climate models are
used. As an alternative approach, we introduce a methodology, coined
“Hydrological Calibration of eXtremes” (HyCoX), in which the calibration of
the hydrological model, as driven by climate model output, is carried out
by maximizing the probability that the modeled and observed high streamflow
extremes belong to the same statistical population. The application to the
Adige River catchment (southeastern Alps, Italy) by means of HYPERstreamHS,
a distributed hydrological model, showed that this procedure preserves
statistical coherence and produces reliable quantiles of the annual maximum
streamflow to be used in assessment studies.
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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
TIME LAPSE ELECTRICAL RESISTIVITY TOMOGRAPHY AND DISTRIBUTED TEMPERATURE MEASUREMENTS IN THE HYPORHEIC ZONE OF AN ALPINE RIVER
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