Drainage formula (Water Overlay)

Drainage passive: First the flow capacity is calculated Failed to parse (unknown function "\deltat"): {\displaystyle Q_{p,t}=\deltat*q_t/math> The water head at the drainage area is calculated: <math>h_{x,y} = (w_{g,x,y}-z_d)\cdot f_s}

where:

$w_g$ is the ground water level in meters

$z_d$ is the drainage datum height in meters.

$A_d$ is the drainage area size in square meters.

$f_s$ is the average storage percentage of the ground above the drainage.