Ditch Drainage Theories for Homogeneous Anisotropic Soil

Abstract

The problem of seepage of steady rainfall or irrigation recharge into a homogeneous and anisotropic soil medium, drained by equally spaced ditch drains overlying a barrier, is solved. Two general cases of the problem are considered: (1) ditch drains dug down to an impermeable barrier; and (2) ditch drains dug down to a gravel substratum. The proposed solutions are exact in the sense that they are based on potential theory and account for the surface of seepage. The validity of the proposed solution for the first case is tested by comparing the midway water-table heights obtained from it for some specific drainage situations with the corresponding upper and lower theoretical bounds of Youngs. The accuracy of the proposed analytical model for the first case is further tested by comparing the midway water-table height obtained from it for a specific drainage situation with the corresponding height obtained from other numerical work.