Modelling extreme rainfall events: 'blanket approches' when considering soil infiltration For my thesis on modelling an extreme rainfall event with a 2D surface runoff model I'm supposed to consider the effect of soil infiltration on the runoff: In my work description it says I'm supposed to "choose an appropriate approach to model soil infiltration because 'blanket approaches' (if its the correct english translation) have uncertainties". As an 'appropriate approach' I got recommended to use a software which computes a runoff-coefficient. But what are the 'blanket approaches'? I probably need to use one or more of those 'blanket approaches' and compare them with the results from the software. Any ideas what is meant?
I would be surprised if the rainfall-runoff relationship would show a linear relationship for extreme events. I would consider that to be a blanket approach, if you mean using a constant coefficient. So consider using a higher order relationship.

Another thing to consider is whether the rainfall runoff relationship depends on the soil moisture. Maybe check out how other models like SWAT deal with this.

To be honest, I think that the amount of soil infiltration will be insignificant for extreme rain events because it occurs too slowly compared to the rainfall rate and other uncertainties.