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. ¿ 2000 American Geophysical Union