Has surface water flooding been modelled to include information at the street/property level on drainage? Does this change by geography?

Most third party global flood maps use a generalised assumption that any areas classified as ‘urban’ can accommodate the 5-year rainfall volume in storm drains before flooding occurs. The rainfall amount that is calculated as having a 5-year return period is therefore removed from rainfall totals (i.e. those calculated for the 20, 50, 100, 200, 500 and 1500-year return periods) before hydraulic models are run. There are two exceptions that have used different urban drainage assumptions, the US and Canada.