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• A simple and efficient unstructured finite volume scheme for solving the shallow water equations in overland flow applications

  L. Cea, E. Bladé

  Water Resources Research (2015). Vol. 51 (7), pp. 5464-5486

  
  

  Abstract

  This paper presents the Decoupled Hydrological Discretisation (DHD) scheme for solving the shallow water equations in hydrological applications involving surface runoff in rural and urban basins. The name of the scheme is motivated by the fact that the three equations which form the two-dimensional shallow water system are discretised independently from each other and thus, the numerical scheme is decoupled in a mathematical sense. Its main advantages compared to other classic finite volume schemes for the shallow water equations are its simplicity to code and the lower computational cost per time step. The validation of the scheme is presented in five test cases involving overland flow and rainfall-runoff transformation over topographies of different complexity. The scheme is compared to the finite volume scheme ofRoe [1986], to the simple inertia formulation [Bates et al., 2010], and to the diffusive wave model. The test cases show that the DHD scheme is able to compute subcritical and supercritical flows in rural and urban environments, and that in overland flow applications it gives similar results to the second order scheme of Roe with a lower computational cost. The results obtained with the simple inertia and diffusive wave models are very similar to those obtained with the DHD scheme in rural basins in which the bed friction and topography dominate the flow hydrodynamics but they deteriorate in typical urban configurations in which the presence of supercritical flow conditions and small scale patterns boost the relevance of the inertial terms in the momentum equations

  Abstract
  This paper presents the Decoupled Hydrological Discretisation (DHD) scheme for solving the shallow water equations in hydrological applications involving surface runoff in [...]

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• Avances en el análisis del material leñoso en ríos: incorporación, transporte e influencia en el riesgo por inundaciones

  V. Ruiz-Villanueva, A. Díez-Herrero, J. Bodoque, E. Bladé

  Cuaternario y geomorfología (2015). Vol. 29 (3-4), pp. 7-33

  
  

  Abstract

  El transporte y depósito de restos de vegetación en los ríos (troncos o árboles completos, ramas y raíces, material leñoso en general) puede agravar las consecuencias de los eventos de avenida e inundación e incrementar su peligrosidad potencial. Este material puede afectar especialmente a infraestructuras como drenajes, puentes, etc., que intersectan ríos en cuencas montañosas forestadas. Una práctica muy extendida y aceptada hasta hace pocos años ha sido la extracción sistemática de este material leñoso de los cauces como medida de prevención. Sin embargo, se ha demostrado que esta práctica puede resultar inútil (el material es transportado y depositado tras cada inundación), e incluso no beneficiosa para el equilibrio natural del sistema fluvial a largo plazo. Por lo tanto, es necesario gestionar la presencia del material leñoso en los ríos, e integrar su estudio en los análisis de peligrosidad y riesgo por inundación. Sin embargo, en España existen escasos trabajos en los que el material leñoso haya sido objetivo fundamental de estudio y, por tanto, tampoco existe demasiada bibliografía relacionada con esta temática. En este trabajo, se presenta una exhaustiva revisión de los principales métodos empleados para evaluar la peligrosidad de las avenidas e inundaciones que incorporan material leñoso. Asimismo, se propone una metodología integral para estudiar esta carga de detritos leñosos en ríos. En primer lugar, hay que caracterizar la dinámica de incorporación de este material a los cauces. Para ello, es necesario establecer las áreas contribuyentes que pueden aportar el material a los cursos de agua y los procesos que lo incorporan. De este modo, es posible estimar el volumen de madera potencialmente disponible, para lo cual se presenta un modelo numérico que permite la simulación del transporte de carga leñosa junto con la hidrodinámica. Asimismo, se analiza la incidencia de la carga flotante en la peligrosidad y el riesgo por inundaciones. Esta propuesta metodológica se ha puesto en práctica en diversos ríos de la Sierra de Gredos (Sistema Central), presentándose una síntesis de algunos de los resultados principales obtenidos. Como conclusión fundamental, se puede afirmar que una correcta gestión de los ríos requiere a su vez de una apropiada gestión de la vegetación de ribera y el material leñoso transportado y depositado en los mismos; y esta gestión debe encontrar el compromiso para mantener las buenas condiciones ecológicas, reduciendo en lo posible los potenciales riesgos

  Abstract
  El transporte y depósito de restos de vegetación en los ríos (troncos o árboles completos, ramas y raíces, material leñoso en general) [...]

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• Large wood transport as significant influence on flood risk in a mountain village

  V. Ruiz-Villanueva, J. Bodoque, A. Díez-Herrero, E. Bladé

  Natural Hazards (2014). Vol. 74 (2), pp. 967-987

  
  

  Abstract

  An important issue that is not considered in most flood risk assessments in mountain villages in Spain is the transport of solids associated with the flood flow, in this case, large wood transport. The transport and deposition of this wood in urban areas may be a potentially worse hazard than the flood flow itself. Despite its importance, large wood is a key ecological element in rivers, so removing it could be an unsuccessful approach. Therefore, efforts are needed in the better understanding of wood transport and deposition in streams. To analyse this process, scenario-based 2D hydrodynamic flood modelling was carried out. Since flood risk assessment has considerable intrinsic uncertainty, probabilistic thinking was complemented by possibilistic thinking, considering worst-case scenarios. This procedure obtained a probabilistic flood map for a 500-year return period. Then, a series of scenarios was built based on wood budget to simulate wood transport and deposition. Results allowed us to identify the main infrastructures sensitive to the passing of large wood and simulate the consequences of their blockage due to wood. The potential damage was estimated as well as the preliminary social vulnerability for all scenarios (with and without wood transport). This work shows that wood transport and deposition during flooding may increase potential damage at critical stream configurations (bridges) by up to 50 % and the number of potentially exposed people nearby these areas by up to 35 %.

  Abstract
  An important issue that is not considered in most flood risk assessments in mountain villages in Spain is the transport of solids associated with the flood flow, in this case, [...]

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• Modelización numérica de zonas fluviales inundables

  E. Bladé, L. Cea, G. Corestein

  Ingeniería del agua (2014). Vol. 18 (1), pp. 71-82

  
  

  Abstract

  La modelización numérica del flujo de agua en ríos es una herramienta que ayuda a dar respuesta a la legislación vigente europea y española referida a riesgo de inundación. Los modelos numéricos disponibles actualmente se encuentran en constante evolución. Mientras hace una década la modelización unidimensional era prácticamente la única alternativa, en el presente se han generalizado los modelos bidimensionales y se empiezan a utilizar los tridimensionales. Gracias a las actuales herramientas SIG, los resultados de la modelización numérica se pueden combinar con datos georreferenciados para realizar una cuantificación sistemática del riesgo de inundación. En este proceso existen aún una serie de desafíos como la consideración de los caudales sólidos y sus efectos en la morfología del cauce, una correcta descripción del flujo en puentes y estructuras, la integración de modelos hidrológicos con los modelos hidráulicos para una mejor consideración de las condiciones de contorno, y finalmente la optimización de las herramientas para disminuir los tiempos de cálculo actuales.

  Abstract
  La modelización numérica del flujo de agua en ríos es una herramienta que ayuda a dar respuesta a la legislación vigente europea y española [...]

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• Two dimensional modelling of large wood transport during flash floods

  V. Ruiz-Villanueva, E. Bladé, A. Díaz-Herrero, J. Bodoque, M. Sánchez-Juny

  Earth surface processes and landforms (2014). Vol. 39 (4), pp. 438-449

  
  

  Abstract

  Large woody material (LW) transported by rivers may be entrapped at critical stream geometry configurations (e.g. bridges) and therefore dramatically increase the destructive power of floods. This was the case in a Spanish mountain river where a flood event with a high degree of LW transport took place in 1997. The aim of this study was to simulate a bridge clogging process and reconstruct the wood deposit patterns, modelling individual pieces of wood moving with the water flow and interacting among them and with the bridge. A two dimensional numerical model was developed to simulate the transport of LW and its effect on hydrodynamics. Different scenarios for the wood transport rate allowed us to study the influence of inlet boundary conditions on bridge clogging. For the studied event, the scenario which best reproduced the bridge clogging effect and flood characteristics was one in which 60% of the total wood entered before the peak discharge. This dropped to 30% at the peak itself, and finally fell to 10% during the recession curve. In addition, the accumulation patterns of LW along the reach were computed and compared with post-event field photographs, showing that the model succeeded in predicting the deposition patterns of wood and those areas prone to form wood jams.

  Abstract
  Large woody material (LW) transported by rivers may be entrapped at critical stream geometry configurations (e.g. bridges) and therefore dramatically increase the destructive [...]

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• Two-dimensional numerical modeling of wood transport

  V. Ruiz-Villanueva, E. Bladé, M. Sánchez-Juny, B. Martí-Cardona, A. Díez-Herrero, J. Bodoque

  Journal of Hydroinformatics (2014). Vol. 16 (5), pp. 1077-1096

  
  

  Abstract

  The transport of wood material in rivers has been the subject of various studies in recent years. Most research has focused on the ecological and geomorphologic role of wood, its recruitment processes and spatial distribution in streams. In this study, we focused on wood transport dynamics, and we have developed a numerical model to simulate wood transport coupled with a two-dimensional (2D) hydrodynamic model. For this purpose, wood drag forces were incorporated as additional source terms into the shallow water equations, which are solved together with wood transport by using the finite volume method. This new tool has been implemented as a computational module into ‘Iber’, a 2D hydraulic simulation software. The new module analyzes the initial motion threshold of wood based on the balance of forces involved in the wood's movement, and computes the position and velocity of differently shaped logs using a kinematic approach. The method also considers the interaction between the logs themselves and between the logs and the channel walls or boundaries. Flume experiments were used in a straight channel with obstructions to validate the model's capacity to accurately reproduce the movement of floating logs.

  Abstract
  The transport of wood material in rivers has been the subject of various studies in recent years. Most research has focused on the ecological and geomorphologic role of wood, [...]

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• Large wood in rivers and its Influence on flood hazard

  V. Ruiz-Villanueva, A. Díez-Herrero, J. Bodoque, E. Bladé

  Cuadernos de investigación geográfica (2014). Vol. 40 (1), pp. 229-246

  
  

  Abstract

  In terms of flood hazard, the presence of large wood (logs, trees, branches and roots) in rivers may aggravate the consequences of flood events. This material may affect infrastructures such as bridges, weirs, etc., especially those intersecting forested mountain rivers. Until recently, a widely accepted practice was to systematically remove wood debris from river channels as a preventive measure. However, studies have shown that this practice may be useless as the material is transported and deposited after each flood and may even not benefit the long term natural balance of the river ecosystem. Therefore, the presence of this woody material in rivers must be managed and included in flood hazard and risk analysis. In this paper we present a comprehensive methodological approach to study the role of large wood in rivers, with a focus on flood hazard. First, to understand the dynamics of wood recruitment, the contributing areas delivering wood to the streams have to be delineated and the recruitment mechanisms studied. Thus, an estimate can be obtained of the potential volume of deliverable wood. To analyse wood transport we present a numerical model, which allows simulates the behaviour of individual pieces of wood together with hydrodynamics. Finally, we analyse the impact of wood on the magnitude of flood events (in terms of water level, flow velocity or flooded areas), using as an example a flood which occurred in December 1997 in the Sierra de Gredos. The results allowed us to reproduce the wood deposit patterns during the event and to reconstruct the bridge blockage. This caused the upstream water level to rise by up to 2 meters and reduced the flow velocity, which favoured debris and sediment deposits. Consequently, the effects of flooding were equivalent to those of a greater magnitude event. This increase in the flood hazard has been numerically quantified.

  Abstract
  In terms of flood hazard, the presence of large wood (logs, trees, branches and roots) in rivers may aggravate the consequences of flood events. This material may affect infrastructures [...]

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• “Enfoque ráster” del problema hidrodinámico del flujo en lámina libre en 2D

  J. Soler, E. Bladé, J. Bofill, P. Gamazo

  Tecnología y ciencias del agua (2013). Vol. IV (4), pp. 77-92

  
  

  Abstract

  Geographical information systems traditionally provide information using two formats–raster and vector. Each one of these formats is handled according to their independent algorithms. Consequently, any type of hydraulic study performed in a territory contains information that can be classified by these two formats. LiDAR is the most precise technology used to generate Digital Elevation Models (DEM) for large areas, with a spatial resolution of 1 to 2 m and a minimum precision in height. It gives the cartographic information its raster characteristic, with the cell as its basic unit of information. Consequently, this kind of information is very suitable to the generation of structured quadrilateral meshes to numerically model free surface flow in two dimensions. The main objective of this work was to present an adaptation of the classic explicit first order finite volumes scheme to a finite square volumes (FSV) mesh which, directly and without interpolations, makes each cell in the DEM (or raster) equal to the corresponding FSV. Consequently, the dimensions of the FSV are those of the base DEM cell. This is presented herein as a raster approach to the hydrodynamic problem of free surface flow in two dimensions. With the raster approach, the database for the mesh topology does not need to be consulted for each instant of time and, therefore, the efficiency of the numeric process is greatly improved. Consequently, larger-sized problems can be addressed. An additional objective was to compare both approaches by solving an illustrative example.

  Abstract
  Geographical information systems traditionally provide information using two formats–raster and vector. Each one of these formats is handled according to their independent [...]

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• Correlación de parámetros geotécnicos con parámetros de un modelo hidrológico superficial

  C. Caro, E. Bladé, N. Rojas

  Ingenio Magno (2013). Vol. 4, pp. 76-86

  
  

  Abstract

  Este artículo presenta la relación entre parámetros geotécnicos básicos y parámetros del modelo hidrológico de Thomas para balance hídrico de cuencas hidrográficas rurales. Esta relación funciona como una aplicación metodológica de calibración, herramienta útil en modelos distribuidos como es el caso de IBER, que representa un sistema distribuido de simulación numérica para flujo no permanente en lámina libre. Se realizó una exploración en 25 puntos (en 15 subcuencas) de la cuenca de Rio de Piedras (Boyacá), obteniendo muestras de suelo a las cuales se les realizó caracterización geotécnica mediante ensayos de laboratorio.

  Abstract
  Este artículo presenta la relación entre parámetros geotécnicos básicos y parámetros del modelo hidrológico de Thomas para [...]

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• Modelo de transferencia vertical dentro de un modelo hidrológico continuo en un esquema de volúmenes finitos

  C. Caro, E. Bladé, P. Acosto

  L'esprit ingeniuex (2012). Vol. 3 (1), pp. 144-154

  
  

  Abstract

  Tomando como base modelos actuales en hidrología, y de acuerdo a las características y a la base del modelo IBER (modelo matemático bidimensional para la simulación de flujos en ríos y estuarios), se ha ajustado el esquema preliminar de lo que será el componente HMC (Modelo Hidrológico Continuo) del modelo IBER, adaptando condiciones de subsuelo y zona subterránea de manera continua al modelo hidrológico basado en esquemas de volúmenes finitos. El modelo escribe el paso del agua desde su estado como precipitación, pasando por el encharcamiento y flujo superficial, hasta el componente que viaja por infiltración y vía subterránea a través de los acuíferos y zonas de retorno de flujo a zonas superficiales, todo mediante una modelización que tiene como base la solución explícita de ecuaciones que trabajan celda a celda en un esquema de volúmenes finitos

  Abstract
  Tomando como base modelos actuales en hidrología, y de acuerdo a las características y a la base del modelo IBER (modelo matemático bidimensional para [...]

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