Q$1($a$)$ The Richards equation $($Eq$.$ Q$1\mathrm{.}1)$ is used to model variably saturated water flow through

a porous media. Define what all the terms in the equation refer to and also list the

complications associated with its use.

$\frac{(h)}{t}=\frac{}{z}[K(h)\frac{h}{z}+K(h)]-S(h)$

Eq$.$ Q$1\mathrm{.}1$

$($b$)$ Root water uptake can be considered a sink term in the Richards equation. Describe an

approach which can be used to model such uptake as a function of the plant's

transpiration rate.

$($c$)$ List the main variables that govern the rate of transpiration that can be brought into a

combined mathematical approach to quantify this flux under carrying atmospheric

conditions.