Mehdi, Istvan Szamosvari is ...

Mehdi,

Istvan Szamosvari is right. In the USA we have a site that gives us the 100 years storm event for 24 hours duration. You can start with this site, where you put the site address (Latitude and Longitude of a Point (getlatlong.net)), to get the Latitude and longitude of your site. In California, we would go to this site (PF Map: Contiguous US (noaa.gov)) to enter above Latitude and longitude to get the date for storm event and interval we want. 

The formula we use is Q = CIA; where “Q” is the runoff flow in Gallons per Minute (gpm), “C” is the runoff coefficient based on land uses, “I” is the rainfall intensity in Inch per Hour taken at the time of concentration, and “A” is the surface area in ft2. We use I=1 if the area is covered by concrete.

I hope this helps.