Studying the hydrological response of urban catchments using a semi-distributed linear non-linear model

A conceptual rainfall-runoff model for urban catchment, which incorporates, semi-distributed modelling concepts has been developed. In the proposed model, the catchment is divided in external sub-catchments connected to the drainage network. Each external sub-catchment is modelled as two separate conceptual linear elements, a reservoir and a channel, one for the pervious part, the other for the impervious part of the drainage area. The drainage network is schematised as a cascade of non-linear cells and the flood routing is simplified in the form of kinematic wave and represented as a flux transfer between adjacent cells. Tests carried out using data from the Parco dʹOrleans experimental catchment located in the University Campus of Palermo, allowed to focus relative results due to changes the spatial representation of the input rainfall and to changes in the spatial discretisation of the sub-catchments. The results of the simulations have pointed out how both the variation in the spatial representation of the rainfall and the variation in the spatial discretisation of the catchment has a definite influence on the outlet hydrographs, especially for high intensity events.