Search results for " scouring"
showing 10 items of 10 documents
Reduction of scouring downstream of a rigid bed by means of a vegetated carpet: experimental investigation in a laboratory flume
2016
Vegetation is a critical component of aquatic ecosystems and exerts an important role in river morphodynamics. This paper describes the results of laboratory study carried out to investigate the role of vegetation on flow field and erosion process developing in non-equilibrium situations. Particular attention is paid to scour evolving downstream of a rigid bed and to the effect of a vegetated carpet used as a protective measure against scouring. The reported experimental study shows that the introduction of the vegetated carpet results in a more favourable configuration than in its absence determining reduced values of flow velocity, turbulence intensity and bed shear stress, and modifying …
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.
Vegetation against erosion downstream of a hydraulic structure
2016
The present work shows the effects of vegetation on sediment transport process. The volume of sediments transported at different time steps is determined by applying a numerical model previously developed [4] and the model parameters are calibrated by using the experimental data.
Analysis of local scour downstream of bed sills: preliminary results of an experimental work
2006
Bed sills are often used to limit bed degradation, to control bed erosion around bridge piers or downstream stilling basins of dams. In this paper, the local scour that takes place downstream of the bed sill, in addition to the general erosion process, is examined. The data collected during experimental work are used to analyse the applicability of the relationship found in the literature and to define the relation between the maximum scour depth and the flow rate.
Bed scouring downstream of hydraulic structures under steady flow conditions: Experimental analysis of space and time scales and implications for mat…
2011
Abstract Sediment transport and bed deformation in alluvial rivers are space and time dependent. The knowledge of the space and time scales can be helpful for the definition of predictive procedures of an alluvial reach response to changing boundary conditions. In this work, attention is paid to scouring process occurring downstream of the rigid basement of a hydraulic structure. The analysis is focused on transient bed profiles which are determined, under steady flow conditions, by a decrease of the upstream sediment transport rate. In particular, the paper is aimed at improving understanding of the space and time scales required by the alluvial system to reach the equilibrium conditions. …
Non-uniform Sediment Transport Estimation in Non-equilibrium Situations: Case Studies
2014
Abstract Quantitative estimate of sediment transport in alluvial channels is one of the most important task in river engineering. Even today, numerical models of sediment transport processes are confronted with some difficulties, often of conceptual nature. One of these difficulties is the simulation of non-uniform sediment transport in non-equilibrium situations, which requires the characterization of the ability of the alluvial system to immediately overcome the variations of the sediment boundary conditions. In this work a 1-D numerical model, which includes a new expression of the so-called “adaptation coefficient”, has been applied to test its capability to simulate the transient bed p…
Nonuniform sediment transport estimation in non-equlibrium situations: study cases
2014
Temporal Evolution of Scour downstream bed sills
2007
River-bed erosion due to changing boundary conditions: performance of a protective measure
2018
Abstract. Due to the introduction of man-made sediment barriers along a river, the amount of sediment load entering the downstream river reach is different to that leaving the reach, and erosion processes occur downstream of the barrier itself. Designers are often required to take into account the scouring process and to include adequate protective measures against the local scour. This paper addresses the performance of bio-engineering protective measures against the erosion process. In particular, a green carpet, realized with real flexible vegetation, has been used as the protective measure against erosion processes downstream of a rigid bed. Analyses are based on experimental work carri…