Steady seepage in trenches and dams: Effect of capillary flow

Steady seepage from two-dimensional domains is investigated using a dimensionless formulation for variably saturated media that depends on three dimensionless parameters, M, n, and alpha. The parameter M is the product of the anisotropy ratio and the squared ratio of the vertical length scale to the horizontal length scale. The parameter n increases with the uniformity of the pore sizes, and alpha represents the ratio of the domain height to the height of the capillary fringe. Our modeling results show that the seepage face height in rectangular domains is always larger than the seepage face height computed from saturated flow models. The results also show that the seepage face height increases with increasing M, increasing n, and/or decreasing alpha. The outflows computed from the present model are always larger than the outflows computed by the Dupuit assumption. Nomographs for rectangular and trapezoidal domains simulating trenches and dams are presented.