[en] Rainwater runoff management is becoming extremely complex as the result of the
increasingly impervious nature of urban and suburban surfaces. Urbanisation can indeed lead
to high volumes of surface water runoff. This undesirable effect could be reduced by
disconnecting roofs from the sewer system. This study represents a first attempt to establish a
model concerning green roofs and flat roof storage systems based on a physical approach
method. The aim is to deduce their respective effect on water runoff management by
analysing and comparing their performance based on a long period of meteorological
conditions data (1989-1995).