Surface Hydrology: IV°Flow in Sloping, Layered Soil

In a nonuniform soil with rotational symmetry the properties change along a coordinate n that forms an angle a with the vertical. During infiltration there will be a flow component in the parallel direction s downstream, which is proportional to the rain itself and the slope. The horizontal flow is proportional to the vertical flow, the slope, and the coefficient of anisotropy. The last has been calculated for a soil made up distinct layers. In the limiting case of very thin layers or near the saturation point, the vertical and horizontal conductivities are, respectively, the expected arithmetic and harmonic means familiar from saturated flow. The coefficient of anisotropy increases with the rate of vertical flow to a power greater than unity. The horizontal flow component can be many times the vertical one. It finds application in pollution problems and in the study of the underground water regime.