1,720,971 research outputs found
Impact of Weir Location on Discharge Partitioning in Longitudinal Training Walls
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Rivers, Ports, Waterways and Dredging Engineerin
Sediment Nourishments to Mitigate Channel Bed Incision in Engineered Rivers
No full textEngineering modifications of rivers, e.g., dams or groynes, often induce long-term riverbed erosion, which can be mitigated with sediment nourishments. Here, we consider nourishments to mitigate channel bed erosion induced by channel narrowing, as opposed to the more common application downstream of dams. Our objective is to assess and quantify how dumping location, grainsize, and volume are important for mitigation efficacy. Our results show that erosion can be mitigated if nourishments change the sediment flux such that the corresponding equilibrium channel slope is increased. This is achieved by coarsening the sediment flux throughout the reach, increasing magnitude of the sediment flux, or both. Flux is coarsened via additions of sediment at or coarser than the bed surface and nourished sediment should be distributed throughout the incising reach. The second option is nourishing a large volume of relatively fine sediment to increase the equilibrium channel slope. Additions of fine sediment in small volumes decrease the equilibrium channel slope and enhance erosion, because the fine sediment flux makes the gravel more mobile. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Rivers, Ports, Waterways and Dredging Engineerin
Mitigation of long-term bed degradation in rivers: set-up of research
No full textSediment management measures are becoming increasingly popular as they are considered sustainable from both economic and environmental point of view. For example, aimed at counteracting river bed degradation, sediment nourishments have been carried out in the German reaches of the Rhine river while a nourishment pilot study has recently taken place at the Dutch Rhine and a nourishment project has been scheduled for the Danube by the Austrian water management authorities. Moreover, sediment management measures are implemented in various ecological restoration projects (e.g. Trinity river in U.S. and Nunome river in Japan) as sediments and their characteristics form the habitats of the biota, as well as in river training projects around the world.</p
A procedure to store and access the stratigraphy of non – cohesive deposits and its validation with laboratory and field data
No full textGoing 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
Best Practices for Longitudinal Training Walls to mitigate channel bed erosion
No full textRivers, Ports, Waterways and Dredging Engineerin
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
Modeling the transport of sand and mud in the Minnesota River
Full text linkThis thesis is organized into two chapters. The first chapter presents a study on the bankfull characteristics of rivers. The bankfull geometry of alluvial rivers is thought to be controlled by water and sediment supply, and characteristic sediment size. Here we demonstrate a novel finding: when bankfull shear velocity and bankfull depth are correlated against bed material grain size and bed slope, they are to first order independent of grain size and dependent on water viscosity. We demonstrate this using a similarity collapse for bankfull Shields number as a function of slope and grain size, obtained with data for 230 river reaches ranging from silt-bed to cobble-bed. Our analysis shows that bankfull Shields number increases with slope to about the half power. We show that the new relation for bankfull Shields number provides more realistic predictions for the downstream variation of bankfull characteristics of rivers than a previously used assumption of constant bankfull Shields number.
The second chapter presents a study on sediment routing of the Minnesota River. We perform, via numerical modeling, an analysis of the response of the Minnesota River to changes in sediment loading. To achieve this, we developed a one-dimensional, coupled flow, sediment transport, and channel bed/floodplain morphodynamics model and derived model inputs from field parameters where possible. We show that sediment output from the system is predominantly wash load, and that changes in bed material input has little effect on sediment output in 600 years. However, changes in wash load input has a near-immediate effect on sediment output. Thus, reducing input of wash load would have greater impact on sediment yield of the Minnesota River than reducing input of bed material load.Item withdrawn by Laura Spradlin ([email protected]) on 2014-06-26T14:32:14Z
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