Étude de la sensibilité des paramètres d'un modèle « rural » sur des bassins versants urbanisés

摘要

Several models can be used in order to represent the hydrological processes in an urbanized catchment. Developing those models has been with respect to modeling objectives, spatiotemporal scale and hydroclimatic and spatial data availability. These models can be explicit, hence complex and data demanding, or rather implicit, but lacking direct linking between the model parameters and the urbanization features. Leaning toward simplicity, we aim at developing an efficient modeling tool that permits implicitly to take into account the spatial configuration (urban landscape vs. natural surfaces) and temporal evolution at the scale of an urbanized hydrological catchment. Development of such tool can be achieved by complexifying step-by-step a starting model structure that is not dedicated to urbanized contexts. Before conducting structure modifications, the first step to take is to determine which model functions can be modified. In this paper, we analyze the initial structure and the sensitivity of the parameters that it contains to the presence of urban surfaces within the catchment. For this end, a large sample of 365 French and American catchments was prepared. These catchments are of various sizes going from 1 to 5000 km(2) and represent a large panel of hydroclimatic conditions. The model was calibrated on two periods for each catchment, leading to 730 catchment-period couples for which the fraction of the urban cover was determined. The sensitivity analysis of the model parameters and other hydrological indicators with respect to this fraction was conducted for a selection of area-homogeneous 416 catchment-period couples. The results of this empirical study have shown (1) good model performances at the hourly time step regardless of the urban condition of the catchment and (2) that the model parameters and the hydrological indicators are significantly different with regards to intensively or slightly urbanized catchments, reflecting faster and greater streamflows for intensively urbanized situations.