abstractioninstantiates an object from class of abstraction
# S3 method for default
abstraction(rainfall,
abstractionParams=list(canopyAbstraction=NULL,
surfaceAbstraction=NULL))a vector : a time series of precipitation hyetograph (mm)
a list: including parameters of simple surface and simple canopy methods.
canopyAbstraction depth of canopy abstraction in (mm). default to zero
surfaceAbstraction depth of surface abstraction in (mm). default to zero
a list: an object from class of abstraction