Influence of urban expansion on the hydrology of small catchments: development of the suburban PUMMA model by coupling of urban and rural hydrological models
Influence de l'expansion urbaine sur l'hydrologie de petits bassins : développement du modèle périurbain PUMMA en couplant un modèle urbain et un modèle rural
Résumé
Urban expansion mainly affects suburban areas. These areas are subject to rapid modifications such as an increase of impervious areas or concentration of runoff in sewer systems. These changes have an impact on local hydrology and can induce floods, pollution or decrease of groundwater resource. Distributed hydrological models are useful tools for water management in these areas. This paper presents the PUMMA model simulating the rainwater flux both in urban and in rural areas. PUMMA follows an object-oriented approach. The landscape is discretized into cadastral units in urban areas and irregular hydrological response units, resulting from intersection of land use, geology, soil and sub-basin maps in rural areas. The considered hydrological processes are infiltration in natural soils and hedgerows, subsurface flow in the saturated layer and overland flow in rural and urban areas, 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 (e.g. via storm water overflow devices), which allows the modelling of complex suburban drainage systems with multiple outlets. The paper presents the model structure and the application to the Chaudanne catchment (2.7 km2) which is located in the suburbs of Lyon, France.