Abstract
Distributed modelling in hydrology assess catchment subdivision to take into account physic characteristics. In this paper, we testthe effect of land use aggregation scheme on catchment hydrological response. Evolution of intra-subcatchment land use is studiedusing statistic and entropy methods. The SCS-CN method is used to calculate effective rainfall which is here assimilated to hydrologicalresponse. Our purpose is to determine the existence of a critical threshold-area appropriate for the application of hydrologicalmodelling. Land use aggregation effects on effective rainfall is assessed on small mediterranean catchment. The resultsshow that land use aggregation and land use classification type have significant effects on hydrological modelling and in particularon effective rainfall modelling.