4RICHARDS L A. Capillary conduction of liquids though porous mediums[J]. Physics, 1931, 1(5): 318-333.
5VAN GENUCHTEN M T H. Closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J]. Soil Sci Soc Am, 1980, 44: 892-898.
6KRAHN J. An engineering methodology: seepage modeling with SEEP/W & stability modeling with SLOPE/W[M]. Calgary: Geo-slope International Ltd, 2004:251-252.