Laboratorio virtual LAVIDITA

Lavidita proporciona al alumno de un entorno que le permitirá potenciar tanto su capacidad científica, mejorar su productividad académica, mediante una herramienta docente didáctica, de fácil uso que le resulte práctica y eficaz para introducirse en el campo de La hidráulica, hidrodinámica, morfodinámica fluvial y otros fenómenos de flujos asociados al medio ambiente. Este proyecto virtual a su vez vence las barreras prácticas en la docencia experimental y permite al alumno el acceso a experimentos no habituales en laboratorios convencionales. La metodología de aplicación es un Cd interactivo muy simple en el cual se desarrollan básicamente tres temas: transporte de sedimentos, mecánica de fluidos y mezcla mediante ejemplos visuales y gráficos interactivos del desarrollo de experimentos controlados, en los que le permite resolver problemas, hacer demostraciones, mediciones y otras actividades prácticas y teóricas

Tsunamis generated by fast granular landslides: 3D experiments and empirical predictors

Landslides falling into water bodies can generate impulsive waves, which are a type of tsunamis. The propagating wave may be highly destructive for hydraulic structures, civil infrastructure and people living along the shorelines. A facility to study this phenomenon was set up in the laboratory of the Technical University of Catalonia. The set-up consists of a new device releasing granular material at high velocity into a wave basin. A system employing laser sheets, high-speed and high-definition cameras was designed to accurately measure the high velocity and geometry of the sliding mass as well as the produced water displacement in time and space. The analysis of experimental data helped to develop empirical relationships linking the landslide parameters with the produced wave amplitude, propagation features and energy, which are useful tools for the hazard assessment. The empirical relationships were successfully tested in the case of the 2007 event that occurred in Chehalis Lake (Canada).Peer ReviewedPostprint (author's final draft

Coherent structures in oscillatory flows within the laminar-to-turbulent transition regime for smooth and rough walls

This is an Accepted Manuscript of an article published by Taylor & Francis Group in [Journal of hydraulic research] on [2016], available online at: http://www.tandfonline.com/10.1080/00221686.2016.1174960We investigate coherent structures present in oscillatory boundary layers over smooth and rough beds for Reynolds numbers between 103 and 104, in the transition to turbulence regime. A two-camera 2D- particle image velocimetry (PIV) system was used to visualize coherent structures in an oscillatory-flow tunnel. The obtained results show that smooth-bed flow is populated by vortex-tube structures that are formed due to the Kelvin–Helmholtz instability. Three types of coherent structures are observed in the rough-wall experiments: vortices randomly distributed in space; turbulent bursts – spatial structures without a clear shape compared to vortices but with a longer life than the former; and shear layers of vortices originating due to flow separation from some of the grains on the bed. The reported study contributes to the description of coherent structures in oscillatory flows that are captured with the PIV technique, particularly a new structure in flows over rough beds in the transition to turbulence regime.Peer ReviewedPostprint (author's final draft

Erosión local en pilas de puente: los procesos y su mitigación. Aplicación al pabellón puente de la Expo 2008 de Zaragoza

Se exponen los avances en el estudio de la erosión local en pilas de puente gracias a la experimentación en modelos a escala reducida en laboratorio. Se describe la evolución temporal, las características de la erosión local en pilas de base cuadrada y circular, la influencia de las presiones no hidrostáticas, así como también la protección que ha de utilizarse para mitigar la erosión. Desde el punto de vista de la ingeniería el uso de modelos reducidos es imprescindible debido a la complejidad de los fenómenos que intervienen. Se presenta la aplicación a la evaluación del riesgo de erosión fluvial en una pila compleja de gran anchura, construida en el cauce del río Ebro en Zaragoza. Se describe el problema de erosión local, las características del modelo físico ensayado y los mantos de escollera que consiguen detener la erosión, así como la ejecución y auscultación de esta protección.Peer Reviewe

Versatile image-based measurements of granular flows and water wave propagation in experiments of tsunamis generated by landslides

Landslides falling into water bodies can generate destructive waves, which can be classified as tsunamis. An experimental facility to study this phenomenon has been set up. It consists of a landslidegenerator releasing gravel at high-speed into a wave basin. A non-intrusive system has been designed ad-hocto be able to measure the high velocity and the geometry of the landslide as well as the generated waves characteristics. The measurement system employs the treatment of images captured by a high-speed camera which records the launched granular material illuminated by a laser sheet. A grid of laser sheets marks thebasin water surface. The water has been filled by a small amount of kaolin to properly reflect the laser lightat water surface. Thus, by filming with high definition cameras the perturbed water surface and successively processing the resulting images, it has been possible to measure the generated waves. The measurement framework employs a versatile camera calibration technique which allows accurate measurements in presence of: (1) high lens distortions; (2) pronounced non-parallelism condition between camera sensor and plane of measurement coincident with the laser sheet. The maximum resolution of the measurement tool is0.01 mm, while the maximum uncertainty due to systematic error has been estimated to be 15% for theworst-case scenario. This work improves the suitability of image-based measuring systems in granular flows and free surface hydraulics experimentsThis work was funded by GITS and the 3 years’ national project DEBRIS FLOW (CGL 2009-13039) ofthe Spanish Ministry of Education. Francesco Bregoli has been supported by the 4-years grant FPU2009-3766 of the SpanishMinistry of Education. Authors want to thank Dr. Cecilia Caldini (IDOM Consulting, Barcelona) for the 3D reconstruction ofthe laboratory setup.Peer ReviewedPostprint (published version

Flow structure and resistance in flexible vegetated channels

The present paper helps to understand the behaviour of the flow through plants, as a first approximation to the environmental interactions happening in natural rivers.Peer ReviewedPostprint (author’s final draft

Escorrentía y transporte sólido en la cuenca torrencial de la riera de Las Arenas. Metodología de investigación y primeros resultados

[ES] Algunos ríos de la cuenca mediterránea española se caracterizan por ser de escasa longitud, gran pendiente y carácter torrencial, en sentido meteorológico, hidrológico e hidráulico, causando avenidas catastróficas. El artículo presenta el estudio realizado en la riera de Las Arenas durante tres años y medio con el objetivo de cuantificar el caudal y el transporte sólido de fondo en avenidas. Se trata especialmente la instrumentación de la cuenca (pluviómetros, pluviógrafos, estación de aforos y trampa de sedimentos), la calibración de los instrumentos e instalaciones (incluyendo un modelo reducido), los primeros datos obtenidos en las 6 avenidas registradas y un análisis hidrológico mediante el modelo HEC 1.Este trabajo ha contado con la ayuda del proyecto AMB92-0638 de la CICYT. Agradecemos la colaboración de la Junta de Aguas de la Generalitat de Cataluña, la Diputación de Barcelona, el Instituto Nacional de Meteorología y los Ayuntamientos de Matadepera, Terrassa y Rubí. Han participado en distintas partes del trabajo Ricard Ferrer, Alberto Casart, Celso García García y Cristina Pérez Platas.Martín Vide, JP.; Niñerola Chifoni, D.; Bateman Pinzón, A.; Gómez, L. (1996). Escorrentía y transporte sólido en la cuenca torrencial de la riera de Las Arenas. Metodología de investigación y primeros resultados. Ingeniería del Agua. 3(3):29-44. https://doi.org/10.4995/ia.1996.2702SWORD29443

Development of preliminary assessment tools to evaluate debris flow risks

In the framework of the IMPRINTS European Research Project (FP7), a toolbox for fast assessment of debris flow hazard has been developed. The aim of this toolbox is to implement different existing models inside a common package useful for a fast evaluation of potential hazard. The initiation and propagation of the debris flow is included. One of the requirements of the projects is to define different scenarios with different detail levels in data input. As an example of this, the results could be obtained just using topographical data or improve accuracy by adding geological and hydrological data.Postprint (published version

Morpho-fluvial analysis of headwater catchments: an example from the Central-Eastern Pyrenees

Geomorphometry of headwater catchments has been poorly reported in the Central-Eastern Pyrenees. This study presents a series of parameters obtained for Central-Eastern Pyrenean headwater catchments. The database consists of 3,005 first-and 655 second-order catchments. These catchments have been digitalised, identified, and attributed a value for each parameter. The parameters investigated are divided into three groups: relative to catchments, relative to streams and morpho-hydrological ratios. Histograms reveal similarities between orders for some parameters such as mean slope or orientation, while stream orders seem to condition metrical parameters (area, perimeter, stream length). Streams have been fragmented to assess different values for slope. Values for slope over a small portion of the stream near the outlet seem to show clearer differences between orders. With regard to morpho-hydrological ratios, catchments show better distinctions between orders for the Melton and Lemniscate ratios than for the form factor or the basin elongation. The power-law relationship between catchment area and stream length recognised for large fluvial systems is shown here to follow a linear trend at small values. An attempt to identify the morpho-structural regionalisation differentiating the Axial Pyrenees from the pre-Pyrenees is made based on the parameters. However, applying the methodology to other environments could improve the context of the current results. Similar studies could also benefit from the development of such databases.Postprint (author's final draft

Influencia del ángulo de orientación de estribos y espigones en los procesos de erosión local

[ES] El objeto de este trabajo es estudiar la influencia del ángulo de orientación con respecto a la corriente de un estribo de puente o espigón en la evolución temporal y en el valor final de la erosión local. Con los resultados obtenidos en el laboratorio se ha definido la curva q - Kq, siendo _ el ángulo de inclinación y Kq la relación entre las erosiones máximas para un ángulo q cualquiera y q = 90º (estribo perpendicular a la corriente). Las conclusiones extraídas confirman las hipótesis de los trabajos más recientes que afirman que el valor máximo de erosión corresponde al ángulo de 90º. Se ha estudiado también la evolución temporal de la profundidad de la cavidad siguiendo las formulaciones de Ettema, Franzetti et al. y Whitehouse obteniéndose, en general, buenas correlaciones.El estudio fue realizado con el apoyo del Ministerio de Educación y Ciencia, el proyecto HID96-0971, la Xarxa d’Hidrologia Mediterrània de la Generalitat de Catalunya y en el ámbito de los proyectos PBIC/C/CEG/2355/95 y PRAXIS/3/3.2/CEG/32/94 financiados por la ‘Fundaçao para a Ciência e Tecnologia’ de Portugal.Roca I Collell, M.; Heleno Cardoso, A.; Martín Vide, JP.; Bateman Pinzón, A. (2000). Influencia del ángulo de orientación de estribos y espigones en los procesos de erosión local. Ingeniería del Agua. 7(3):263-269. https://doi.org/10.4995/ia.2000.2849SWORD26326973Ahmad, M. (1953) Experiments on designs and behaviour of spur dikes. Proc. IAHR. Conf. Minnesota, pp 145-159.Cardoso, A.H. Eros (es localizadas junto de espor(es fluviais e de encontros e pilares de pontos. Informe del CEHIDRO, Instituto Superior Técnico, UTL, Lisboa (versión provisional).Cardoso, A.H., Bettes, R. Time evolution and effect of channel geometry on local scour at bridge abutment. Journal of Hydraulic Engineering (aceptado para su publicación).Dongol, D.M.S. (1984) Local scour at bridge abutments. Tesi de doctorado. University of Auckland. Department of civil engineering. Report nº 544.Ettema, R. (1980). Scour at bridge piers. University of Auckland. Department of civil engineering. Report nº 216.Franzetti, S., larcan, E., Mignosa, P. (1982). Influence of tests duration on the evaluation of ultimate scour around circular piers. International Conference on the Hydraulic Modelling of Civil Engineering Structures, paper G2, Coventry, England.Kandasamy, J.K. (1985). Local scour at skewed abutments. University of Auckland. Department of civil engineering. Report nº 375.Kandasamy, J.K. (1989) Abutment scour. Tesi de doctorado. University of Auckland. Department of civil engineering. Report nº 458.Kothary, U.C., Ranga Raju, K.G., Garde, R.J. (1992) Livebed scour around cylindrical bridge piers. Journal of Hydraulic Research. Vol. 30, nº 5. pp 701-715.Kwan, T.F. (1984) Study of abutment scour. University of Auckland. Department of civil engineering. Report nº 328.Kwan, T.F. (1988) A study of abutment scour. Tesi de doctorado. University of Auckland. Department of civil engineering. Report nº 451.Laursen, E.M. (1958) Scour at bridge crossings. Iowa. Highway Research Board Bulletin, nº 8, Iowa Institute of Hydraulic Research, State University of Iowa, USA.LNEC (1982) Canal de inclinaç(o variável. Descriç (o do tanque de montante, canal propiamente dito, tanque de jusante e circuito de retorno. Ministerio de Habitaç (o eobras públicas. Laboratorio Nacional de Engenharia Civil.Melville, B.W. (1992). Local scour at bridge abutments. Journal of Hydraulic Engineering, ASCE. Vol. 118, nº 4 April, pp 615-631.Melville, B.W. (1995). Bridge abutment scour in compound channels. Journal of Hydraulic Engineering, ASCE. Vol. 121, nº 12 December, pp 863-868.Melville, B.W. (1997). Pier and abutment scour: integrated approach. Journal of Hydraulic Engineering, ASCE. Vol. 123, nº 2, February, pp 125-136.Richardson, E.V., Harrison, L.J., Richardson, J.R. Davies, S.R. (1993). Evaluating scour at bridges. Federal Highway Administration, Pub. FHWA-P-90-017, Virginia, USA.Whitehouse, R.J.S. (1997). Scour at marine structures: a manual for engineers and scientists. HR Wallingford Research, report SR417, Wallingford, UK