 The well spacings in these areas can be so wide (more than 1000m) that the installation of "vertical" drainage systems could be relatively cheap compared to "horizontal" subsurface drainage (drainage by pipes, ditches, trenches, at a spacing of 100m or less).For the design of a well field for control of the water table, the WellDrain model  may be helpful.A classification of drainage systems is found in the article Drainage system (agriculture).