Efficient method for simulating gravity‐dominated water flow in unsaturated soils

Abstract

Numerical convergence difficulties associated with nonlinearity in the hydraulic property functions are often encountered when simulating gravity‐dominated water flow in unsaturated soils using Richards' equation. A new approach for approximating the gravity term in Richard's equation is developed. Tests on a wide variety of soils show it is superior to existing Picard and Newton approaches. It is more reliable and efficient and allows larger time steps to be used.