Modeling of flood risk is a branch of hydrology, a discipline that studies the distribution and movement of water masses. In particular, it defines the probability of flooding from water courses and the portions of the territory involved by phenomena of different intensity.

It is a relevant instrument for land planning, since it allows to highlight areas exposed to flood risk, or designing interventions to mitigate the risk.

**Main applications**

Time series of rainfall data are used to calculate rainfall probability curves, describing extreme rainfall events calculated for specific return periods.

These curves, together with the geometric model and the values of permeability and roughness allow to calculate the hydrograph of the study area.

The analysis of the characteristics of the basin is performed by the software hec-geoHMS, which, starting from an accurate digital terrain model (DTM), allows defining hydrographic gradients, slopes and the data of permeability and roughness of the basin.

In addition to the geometric model of the study area, the characteristics of the territory, such as permeability and roughness of the terrain derived from spatial data as geological maps, land use maps, etc. are used to calculate flow rates of the flood wave, resulting from a reference rainy event. Values are compared with the geometrical model using a special software that calculates the height of the flood wave in each section considered.