Search results for " Structural"
showing 10 items of 1751 documents
Empirical Investigation of Curve Number Method Parameters in the Mediterranean Area
2012
AbstractThe curve number (CN) method is widely used as a technique for estimating surface runoff depth from rainstorms. This simply lumped method is based on the main parameter CN, which represents the lumped expression of basin absorption, and on a parameter that represents interception, infiltration during the early part of a storm, and surface depression storage, called initial abstraction. In this paper, CN is evaluated at the basin scale from rainfall-runoff multiday events, in the observation period 1940–1997 (recorded length mean equal to 20 years) for 61 Sicilian basins with three different methods: NEH4 method, asymptotic fitting method, and a least-squares method. A first analysis…
Testing the Outflow Process over a Triangular Labyrinth Weir
2017
In this paper, the dimensionless stage-discharge relation for a sharp-crested triangular labyrinth weir, determined in a previous study, is initially tested by some experimental runs carried out in a laboratory flume. According to this relationship, the flow magnification is affected by the length-magnification ratio and the head to one cycle width ratio. The measurements allowed to test the applicability of this dimensionless relation for different values of both the angle of the sidewall to the main flow direction and the weir height. Finally, the proposed dimensionless equation was also tested by using experimental measurements carried out for broad-crested triangular labyrinth weir.
Flow resistance ofPosidonia oceanicain shallow water
2006
Management of coastal waters and lagoons by mathematical circulation models requires determination of the hydraulic resistance of submerged vegetation. A plant typical of sandy coastal bottoms in the Mediterranean Sea is Posidonia oceanica, which is constituted by very thin and flexible ribbon-like leaves, about 1 cm wide and up to 1.5 m long, and usually covers the bottom with a density of 500-1000 plants/ m2. From the hydraulic viewpoint, P. oceanica constitutes a particular roughness, because, as the velocity increases, the leaves bend more and more until they lie down on the bottom. Although P. oceanica is widespread, in the technical literature it is difficult to find indications about…
Role of Modeling Uncertainty in the Estimation of Climate and Socioeconomic Impact on River Water Quality
2012
AbstractClimate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty and the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based…
1-D numerical simulation of sediment transport in alluvial channel beds: study cases
2011
ABSTRACT Quantitative estimate of sediment transport processes is important especially in river-control engineering and for water management projects. In this paper the sediment routing of a 1-D model is presented and applied to some study cases. The procedure simulates the variations of bed roughness conditions due to natural sorting and to generation and migration of bed forms. The suspended-load and the bed-load are treated separately.
Vegetation effects on cross-sectional flow in a large amplitude meandering bend
2017
ABSTRACTCross-stream circulation, which develops in meandering bends, exerts an important role in velocity redistribution. This paper investigates how the presence of vegetation could affect the evolution pattern of cross-stream flow along a high-curvature meandering bend. The analysis is conducted with the aid of data collected in a meandering laboratory flume over non-vegetated and vegetated beds. The experiments reveal that, once the vegetation is introduced, the flow pattern determined by the channel’s curvature is interrupted. In the presence of vegetation, the central-region circulation cell seems to be divided into thin circulation cells developing at the top of the vegetated layer a…
Modeling Rill Erosion at the Sparacia Experimental Area
2015
In this paper the contributions of rill and interrill components to total soil erosion monitored at event scale at the Sparacia experimental area, Southern Italy, were firstly compared and the dominance of the rill component was detected. Then, the reliability of two empirical relationships between the rill length and its eroded volume and among the morphological variables (length, width, depth and volume) describing the channelized process was tested using both direct measurements of rills, carried out for the October 3, 2011 event, and those of ephemeral gullies surveyed on February 2010 at Sparacia. The measurements of rills detected by the direct field relief were compared with those ob…
Simplified Probabilistic-Topologic Model for Reproducing Hillslope Rill Network Surface Runoff
2015
AbstractThis work presents a simplified probabilistic-topologic model for reproducing rill network surface runoff on a square-plane hillslope. The model requires only two parameters: the first is related to the production capacity of overland flow of the hillslope, at the initial conditions of the process, and the second depends on the sinuosity of the rill network. From a hydrological point of view, the following parameters account for the effects that essentially delineate the hydrologic response of a natural hillslope: rainfall intensity, hillslope roughness, and slope. Obviously, the reliability of the model is pending experimental validation that has only just begun. However, a prelimi…
Finite-Element Modeling of Floodplain Flow
2000
A new methodology for a robust solution of the diffusive shallow water equations is proposed. The methodology splits the unknowns of the momentum and continuity equations into one kinematic and one parabolic component. The kinematic component is solved using the slope of the water level surface computed in the previous time-step and a zero-order approximation of the water head inside the mass-balance area around each node of the mesh. The parabolic component is found by applying a standard finite-element Galerkin procedure, where the source terms can be computed from the solution of the previous kinematic problem. A simple 1D case, with a known analytical solution, is used to test the accur…
Wastewater Reuse Effects on Soil Hydraulic Conductivity
2004
The wastewater total suspended solids (TSS) concentration effects on the saturated hydraulic conductivity, \iK\ds, of a clay and a loam soil were investigated on laboratory repacked soil cores by a constant head permeameter. Both municipal wastewater (MW) and artificial wastewater (AW) with different TSS concentrations were used, with the aim to evaluate, by comparison, the effects of biological activity. The development of a surface sealed layer was investigated in loam soil columns supplied with AW and equipped with water manometers at different depths to detect the hydraulic head gradient changes. In the loam soil, \iK\ds reduced to about 80% of the initial value after infiltration of 17…