Urban drainage systems design and management are strictly connected to meteorological forcing. For design purposes
synthetic forms (e.g. depth duration frequency curves) are usually adopted to represent the meteorological solicitation,
while a stochastic representation could be more promptly used to investigate the effects of potential climate change both
on the design and on the efficiency of urban drainage devices. A simplified semi-probabilistic approach, relying on
simple models of the stochastic rainfall process and of the rainfall-runoff (hydrological) transformation, is expected to be a
sound tool. Since the rainfall process is described through the definition of three random variables and their probability
distribution, the main advantage is the possibility of changing one, two or more characteristics of the rainfall model at a
time. The effect of the change can then be easily evaluated through the application of the hydrological model.
The semi-probabilistic approach is applied to study some aspects of the drainage system design for locations in the Italian
territory. Potential effects of climate change on fictitious urban basins are evaluated through a rainfall stochastic model
calibrated on the basis of long series observations recorded at site. Precipitation climate change scenarios were defined on
the basis of both international climate studies report and local meteorological observation analysis. The effects on the
urban drainage system are evaluated with respect to specific urban drainage devices and the efficiency of the design
procedure in the hypothesis of climate change is finally discussed
