Model Study of Boundary Effects on Ditch Drainage

Increased drainage of agricultural lands has created a need for design information concerning the spacing and depth of tile- and open-ditch drains. In many drainage systems, there is an impermeable layer at some depth below the ground surface. In most theoretical and laboratory conditions, the impermeable layer is considered as the lower boundary of the flow field. The writers are not acquainted with any investigations that have been conducted to determine the depth at which the impermeable boundary has essentially no effect on the flow field. The purpose herein is to examine the effects that the depth of an impermeable layer has on transient subsurface drainage to open ditches.