Search results for "River"
showing 10 items of 564 documents
Investigating the Performance of Enhanced Permeable Groins in Series
2020
The enhanced permeable groin is a novel eco-friendly and cost-effective technique for bank protection and restoration of meander bends. The behavior of bed deformations due to the distance between the structures has to be studied to design enhanced permeable groins in series properly. In this study, scour morphologies around enhanced permeable groins in series, characterized by four different distances and located in a 180°
Study and evaluation of nano-structured cellulose fibers as additive for restoration of historical mortars and plasters
2017
Abstract UPM bio-fibrils are nano-structured cellulose fibers (nano-fibrils) produced by UPM Kymmene-Corporation, a Finnish company. This paper reports a preliminary study about nano-fibrils to determine their possible use for restoration of historical mortars and plasters. The aim of this study is to investigate the behavior of some mixtures added with nano-fibrils in their properties for conservative purposes. These mixtures reproduce the composition of historical mortars and plasters, made of natural hydraulic lime (NHL 3.5) and river sand. After 28 days of hardening, the properties of specimens with nano-fibrils were compared with untreated one to understand how nano-fibrils interact wi…
Simulation of scouring process downstream of a hydraulic structure and analysis of the effect of vegetation
2018
In the present work a 1-D numerical model is applied to simulate the evolution of scouring process and the variation of the bed shear stress during transients. By the help of the model and by using experimental data collected in a straight flume, the paper also investigates how the presence of flexible vegetation on the bed could limit the evolution of the erosion process.
TIME EVOLUTION OF LOCAL SCOURING DOWNSTREAM OF A RIGID BED:lessons learned from experiments
2018
This present work concerns the phenomenon of local erosion occurring downstream a rigid bed of a structure constructed along a river. In particular, attention is focused on the time evolution of the maximum scour depth. This chapter reports a brief review of findings obtained by author using both data appositely collected in a laboratory channel and literature data.
Prediction of river discharges at confluences based on Entropy theory and surface-velocity measurements
2022
Hydrodynamic features of the confluence zone of large rivers are complicated because of their three-dimensional flow structure. The confluence between the Rio Negro and the Rio Solimões, characterised by black and white waters, respectively, ranks among the largest river junctions on Earth. An Entropy-based investigation was carried out to assess the discharge and analyse the 2D structure of velocity distribution for large river flows relying on monitoring of near-surface velocity only. The estimated flow data where compared with in-situ ADCP data gathered across some transects of the Negro and Solimões rivers during both low and relatively high flow conditions. Results are illustrated thro…
Establishing mussel behaviour as a monitoring tool to measure climatic disturbances
2021
Freshwater mussels (FM) are suitable biological indicators to assess environmental stressors. Behaviour is a good parameter to measure rapid mussel’s responses. In this sense, valvometric method, that exploits the Hall sensor (real-time remote monitoring tool), has been used to measure the behavioural responses of mussels (valve opening amplitude and valve opening-closure frequency). During the last two decades, these methodologies have been used to measure the presence of the pollutants in the waterbodies. However, studies that focus on physical disturbances in the environment related to climate changes are lacking. Since future climatic scenarios in Europe predict an increase in temperatu…
Estimating the hydrodynamic and morphodynamic characteristics using Entropy theory at the confluence of Negro and Solimões Rivers
2021
When two mega rivers merge the mixing of two flows results in a highly complex threedimensional flow structure in an area known as the confluence hydrodynamic zone.
Effects of submerged vegetation on flow and turbulence characteristics at the apex section of a meandering flume
2020
Understanding flow characteristics and turbulent structure in the presence of vegetation is important with respect to environmental processes as sediment transport and mixing of transported quantities. In the present paper attention is focused on the kinematic and turbulent processes in presence of flexible submerged vegetation. In particular, the effect of vegetation on the flux of mass distribution and the process of transport is investigated. The analysis is performed with the aid of detailed experimental data collected in a laboratory channel both in the absence and in presence of flexible and submerged vegetation. Results essentially confirms that mass exchanges in the presence of vege…
Velocity and turbulence measurements: uncertainty in the application of the Image-based technique
2018
This work focuses on the application of image-based technique to estimate velocity and turbulent flow characteristics. In particular, in the present work digital imaging technique is used for performing surface velocity measurements of hyper-concentrated flows. The analysis is conducted with the aid of data collected in a scale laboratory flume constructed at the Hydraulic laboratory of the Department of Civil, Environmental, Aerospatial and of Materials Engineering (DICAM) – University of Palermo (Italy). In the present paper a brief summary of results obtained in previous works on the flow velocity estimation error and uncertainty related to the acquisition procedure is reported.
Flow velocity profile and turbulence characteristics in a vegetated straight flume
2008
Vegetation affects the hydrodynamic conditions of an open channel flow with direct implications in physical and biophysical processes. In this paper, the vertical flow velocity distribution of a vegetated flow has been analyzed using experimental data collected in a straight flume. The experimental velocity distributions are positively compared with the hyperbolic tangent profile of a pure mixing layer previously verified by Ghisalberti and Nepf (2002). Peculiarly, for different flow and vegetative conditions, fitting of the hyperbolic tangent profile to the experimental velocity distributions has allowed the localization of the inflection point of the velocity profile at a distance from th…