I    <- seq(0,100,by=1.0)
        t0   <- 0.05 
        ts   <- 0.25
        hs  <-  0.0 # cm
        hf  <- -12.0 # cm
        Ks  <-  8.0 # cm/hour
        t   <- 1/Ks*((I-(hf-hs)*(ts-t0))*log(1-(I/((hf-hs)*(ts-t0))))) # hours
        plot(t,I,xlim=c(0,6),ylim=c(0,25),xlab="t [hour]", ylab="I in [cm]")