\begin{equation}
    \beta_{v,2} = VEG zqs_{veg}^{rap} \left( \frac{1}{1 + U q_{c,drag} r_{sv} }   \right) \equiv VEG zqs_{veg}^{rap} \left( \frac{1}{1 + \frac{r_{sv}}{r_a} }   \right)
\end{equation}
