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Saint-Martin-Vésubie, France

Dehotin J.,IRSTEA | Vazquez R.F.,CSIC - Centro de Investigacion y Tecnologia Agroalimentaria | Braud I.,University of Cuenca | Debionne S.,IRSTEA | Viallet P.,HYDROWIDE
Journal of Hydrologic Engineering | Year: 2010

To better handle landscape heterogeneities in distributed hydrological modeling, an earlier work proposed a discretization based on nested levels, which leads to fully unstructured modeling meshes. Upon such a discretization, traditional numerical solutions must be adapted, especially to describe lateral flow between the unstructured mesh elements. In this paper, we illustrated the feasibility of the numeric solution of the diffusion equation, representing groundwater flow, using unstructured meshes. Thus, a two-dimensional (2D) groundwater model (BOUSS2D), adapted to convex unstructured and irregular meshes was developed. It is based on the approximation of the 2D Boussinesq equation using numeric techniques suitable for nonorthogonal grids. The handling of vertical and horizontal aquifer heterogeneities is also addressed. The fluxes through the interfaces among joined mesh elements are estimated by the finite volume method and the gradient approximation method. Comparisons between the BOUSS2D predictions and analytical solutions or predictions from existing codes suggest the acceptable performance of the BOUSS2D model. These results therefore encourage the further development of hydrological models using unstructured meshes that are capable of better representing the landscape heterogeneities. © 2011 ASCE. Source

Branger F.,IRSTEA | Braud I.,IRSTEA | Debionne S.,HYDROWIDE | Viallet P.,HYDROWIDE | And 4 more authors.
Environmental Modelling and Software | Year: 2010

Distributed hydrological models are valuable tools that can be used to support water management in catchments. However, the complexity of management issues, the variety of modelling objectives, and the variable availability of data require a flexible way to customize models and adapt them to each individual problem. Environmental modelling frameworks offer such flexibility; they are designed to build and run integrated models on the basis of reusable and exchangeable components. This paper presents the LIQUID® framework, developed by Hydrowide since 2005. The purpose of developing LIQUID® was to provide both easier integration of hydrological processes and preservation of their characteristic temporal and spatial scales. It suits a wide range of applications, both in terms of spatial scales and of process conceptualisations. LIQUID® is able to synchronize different time steps, to handle irregular geometries, and to simulate complex connections between components, in particular involving feedback. The paper presents the concepts of LIQUID® and the technical choices made to meet the above requirements, with focuses on the simulation run system and on the spatial discretization of process components. The use of the framework is illustrated by five application cases associated with contrasted spatial and temporal scales. © 2010 Elsevier Ltd. Source

Jankowfsky S.,IRSTEA | Jankowfsky S.,Lee University | Branger F.,IRSTEA | Braud I.,IRSTEA | And 3 more authors.
Journal of Hydrology | Year: 2014

Distributed hydrological models are useful tools for process understanding and water management, especially in peri-urban catchments where the landscape heterogeneity is large, caused by a patchwork of natural and urbanized areas. This paper presents the Peri-Urban Model for landscape MAnagement (PUMMA) built within the LIQUID® modeling framework, specifically designed to study the hydrology of peri-urban catchments. It combines rural and urban hydrological models, and is used for process understanding. The originality of PUMMA is to follow a fully object-oriented approach, for both model mesh building and process representation. Urban areas, represented by cadastral units and rural areas divided in Hydrological Response Units are thus modeled with different interacting process modules. This provides a detailed representation of the runoff generation on natural and impervious areas. Furthermore, the exchange between process modules facilitates the simulation of subsurface and overland flow, as well as groundwater drainage by sewer pipes. Several drainage networks can coexist and interact (e.g. via storm water overflow devices) and water can be stored in retention basins, which allows the modeling of complex suburban drainage systems with multiple outlets. The model is then applied to the Chaudanne catchment (2.7km2), located in the suburbs of Lyon, France. The uncalibrated model results show the importance of surface runoff from impervious areas for summer events and flow contributions from rural zones for winter events. Furthermore, the model reveals that the retention capacity of the Chaudanne catchment is larger than for classical urban catchments due to the peri-urban character of the catchment. © 2014 Elsevier B.V. Source

Branger F.,IRSTEA | Debionne S.,HYDROWIDE | Viallet P.,HYDROWIDE | Braud I.,IRSTEA | And 4 more authors.
Modelling for Environment's Sake: Proceedings of the 5th Biennial Conference of the International Environmental Modelling and Software Society, iEMSs 2010 | Year: 2010

Environmental modelling frameworks are valuable and increasingly used tools for building customized models, in a context where the complexity of management issues and the availability of data require much flexibility. The LIQUID ® framework has been developed since 2005. It is mostly dedicated to hydrological modelling. It aims at easily integrating hydrological processes while preserving their characteristic temporal and spatial scales. LIQUID ® allows the user to build and run integrated models on the basis of reusable and exchangeable modules. It provides templates for easy development of new modules, connections to databases and GIS for data input and output, and module coupling mechanisms, that synchronize different time steps and handle irregular geometries. LIQUID ® suits a wide range of applications, involving various spatial scales and process conceptualisations. The framework is also able to simulate complex interactions between modules, in particular including feedback. The paper will present the recent advances of LIQUID ®, in terms of concepts as well as in terms of technical specifications, and a brief overview of the ongoing main applications. Those deal with the assessment of landscape management impact on hydrology in agricultural and suburban areas, and with the analysis of hydrological responses in the context of flash floods. Source

Jankowfsky S.,IRSTEA | Branger F.,IRSTEA | Braud I.,IRSTEA | Viallet P.,HYDROWIDE | And 2 more authors.
Modelling for Environment's Sake: Proceedings of the 5th Biennial Conference of the International Environmental Modelling and Software Society, iEMSs 2010 | Year: 2010

The world-wide trend towards a growing urbanization mainly affects suburban areas. These areas are subject to rapid modifications such as an increase of impervious areas, concentration of runoff in sewer systems, river regulations, but also a decline of agricultural areas causing a forest increase. These changes have an impact on the local hydrology and can induce floods, pollution or decrease of groundwater resource. Distributed hydrological models are useful tools for water management in these areas. They can simulate floods or the impact of land use scenarios on the water balance. This paper presents the PUMMA model (Peri-Urban Model for landscape MAnagement), dedicated to the hydrology of suburban catchments. The model is built within the LIQUID modelling framework. LIQUID facilitates the development of PUMMA by providing a set of modules for different hydrological processes, templates for easy development of new modules and module coupling mechanisms. PUMMA follows an object-oriented approach. The landscape is discretized into cadastral units in urban areas and irregular hydrolandscapes, resulting from intersection of land use, geology, soil and sub-basin maps in rural areas. Each model unit represents one implementation of a module. The considered hydrological processes are infiltration in natural soils and hedgerows; overland flow in urban zones and over roads, storage in storm water retention basins and flow routing within networks consisting of ditches, natural rivers and sewer pipes. Several drainage networks can coexist and interact, which allows the modelling of complex suburban drainage systems. The paper presents the model structure and a first application to a simple test case. Source

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