E. Bladé

Pressures on a stepped spillway

This paper presents an analysis of the pressure field on the steps of a stepped spillway on an RCC dam. The fundamental component of this study is a series of pressure measurements obtained in the fully-developed zone of skimming flow regime along a reduced-size stepped spillway model constructed at the Department of Hydraulic, Maritime and Environmental Engineering Laboratory of the Technical University of Catalonia (UPC). A mathematical model was fitted to the pressure profiles on the horizontal and vertical faces of the steps. This equation allows designers to estimate the possible negative values of pressure on the vertical and horizontal faces of the steps in the fully-developed zone of skimming flow regime

Analysis of pressures on a stepped spillway

The pressure profiles on the horizontal and vertical step faces of a stepped spillway in the fully developed skimming flow region were measured. These observations allow to provide generalized equations that enable designers to analyze the amount and the location of negative pressures along the steps. The step locations subjected to negative pressure are also discussed including an analysis of the duration of the negative pressures. On the horizontal step faces, negative pressure were only observed on their upstream half for dimensionless discharges larger than dc/h = 1.3. On the vertical step faces, only the region close to the adjacent horizontal face was not subjected to negative pressure

Envisat/ASAR Images for the Calibration of Wind Drag Action in the Doñana Wetlands 2D Hydrodynamic Model

Donana National Park wetlands are located in southwest Spain, on the right bank of the Guadalquivir River, near the Atlantic Ocean coast. The wetlands dry out completely every summer and progressively flood again throughout the fall and winter seasons. Given the flatness of Donana’s topography, the wind drag action can induce the flooding or emergence of extensive areas, detectable in remote sensing images. Envisat/ASAR scenes acquired before and during strong and persistent wind episodes enabled the spatial delineation of the wind-induced water displacement. A two-dimensional hydrodynamic model of Donana wetlands was built in 2006 with the aim to predict the effect of proposed hydrologic restoration actions within Donana’s basin. In this work, on-site wind records and concurrent ASAR scenes are used for the calibration of the wind-drag modeling by assessing different formulations. Results show a good adjustment between the modeled and observed wind drag effect. Displacements of up to 2 km in the wind direction are satisfactorily reproduced by the hydrodynamic model, while including an atmospheric stability parameter led to no significant improvement of the results. Such evidence will contribute to a more accurate simulation of hypothetic or design scenarios, when no information is available for the atmospheric stability assessment.

Source term treatment of SWEs using the surface gradient upwind method

The Authors’ works, who have designed well-balanced 1D schemes for the Saint-Venant equations on irregular geometries, are of interest to develop efficient numerical methods. In recent years, most efforts have focused on improving the performance of 2D models, so that 1D schemes were forgotten to a certain degree, as evidenced by the large number of references of this discussion dealing with 2D models. However, 1D schemes, either by themselves or in combination with 2D schemes, still have advantages relative to lower computational cost and reduced information need. The Discussers would like to highlight two considerations: the first being related to the formulation, whereas the second to the verification.

Ensayo comparativo entre modelos unidimensionales y bidimensionales en la modelización de la rotura de una balsa de materiales sueltos erosionables

El desarrollo de ordenadores cada vez mas potentes y las recientes investigaciones en el campo de la hidroinformatica hace posible la modelizacion del flujo en lamina libre en dos dimensiones producido por una rotura de una presa de materiales sueltos. En el presente trabajo se comparan los resultados obtenidos mediante el modelo unidimensional HEC-RAS y el bidimensional CARPA. La comparativa se hace analizando el efecto que tienen las hipotesis simplificadoras implicitas en el uso de la plataforma HEC-RAS de unidimensionalidad, no infiltracion y existencia de flujo inicial, sobre los hidrogramas de caudal en una seccion testigo situada aguas abajo del eje drenante. Los modelos utilizados reproducen el flujo de agua generado por una posible rotura de la balsa numero 1 del sector 5 del canal Segarra-Garrigues en la cuenca del rio Ebro en Espana.