WaterBalance model - calculate soil water over designated time period
watbal.model(param, weather, WP, FC, WAT0 = NA)
: a vector of parameters
: weather data.frame for one single year
: Water content at wilting Point (cm^3.cm^-3)
: Water content at field capacity (cm^3.cm^-3)
: Initial Water content (mm). If NA WAT0=z*FC
data.frame with daily RAIN, ETR, Water at the beginning of the day (absolute : WAT, mm and relative value : WATp, -)