Hooghoudt's Drain Rate Calculator 
hydraulic conductivity of the soil above drain level Ka = m/day
hydraulic conductivity of the soil below drain level Kb = m/day
depth of the impermeable layer below drain level Di = m
depth of the drains Dd = m
steady state depth watertable midway between the drains Dw = m
spacing between the drains L = m
drain radius r = m
F(x) = -
Calculated Results
equivalent depth d = m
x = -
steady state drainage discharge rate Q = m/day