Seepage from Trapezoidal Canal in Anisotropic Soil

An analytical solution is found for the problem of seepage flow from an unlined trapezoidal canal, taking into account the general anisotropic behavior of the porous medium. Since a canal in an anisotropic medium transforms into one with unequal slopes in an equivalent isotropic porous medium, the solution here is concerned with the problem of seepage flow from an unsymmetrical trapezoidal canal. The method of inversion of hodograph is made use of and expressions for the seepage loss and the locations of the phreatic lines are obtained. Numerical results are presented for the equivalent isotropic flow domain. Using the transformation formulas given, the actual discharge and the locations of phreatic lines in anisotropic medium can be easily obtained for given physical parameters of the actual flow domain. The nonsymmetry of trapezoidal canals of side slopes less than one has considerable influence on the quantity of seepage.