Analysis of the drainage inlets efficiency, variability and vulnerability of the urban system

Pluvial flooding occurs as a consequence of excess rainfall when surface runoff cannot be fully drained by the artificial network (i.e. surface drainage deficiency) and/or when the drainage systems overflows (i.e. drainage systems failures). Because of surface drainage deficiencies, however, flooding events occur quite frequently as a consequence of rain events of lower intensity than the design one, even in case of proper dimensioning of the drainage system. Inlets are in those cases the critical nodes, and efficient drainage is only ensured when care is taken on their appropriate design and positioning within the drainage area. This paper focuses on the impact of the variability of the drainage inlets efficiency on pluvial flood hazard.