STEADY INFILTRATION FROM BURIED POINT SOURCES AND SPHERICAL CAVITIES

Steady infiltration in two‐ and three‐dimensional systems has been treated classically as a process of saturated flow with a free surface. The series this paper initiates deals with the generally unsaturated flow regimes set up by prolonged infiltration into regions with no shallow ambient water table. The analysis is simpler than the classical one in the sense that it does not involve a free surface. With hydraulic conductivity represented by an exponential function of moisture potential, the nonlinear equation for steady flow is transformed into a linear equation which is formally equivalent to that for diffusion in a moving medium. The fundamental point source solution is explored and is used as the basis of an analysis of steady infiltration from spherical cavities. For cavities of small (dimensionless) radius, the infiltration rate is determined almost wholly by capillarity; on the other hand, gravity distorts the pattern of moisture distribution strongly, even when the cavity radius is small. © 1968 by the Chinese Geophysical Society