These data were used to define the CN. The CN is tabulated in the literature and, for open spaces with grass cover on 75% or more of the area and hydrological soil group (HSG) B, it assumes the value of 61, whereas for grass cover on 50–75% of the area and B-HSG, it equals 69. The B group includes soils with a moderate infiltration rate attributable to the texture of silt loam or loam which is the dominant soil texture of the Sarno Plain (Adamo et al. 2014). In Table 4, more details about the input parameters of the sub-catchments, conduits and nodes are available.