AGROFORESTRY DRAINAGE MANAGEMENT MODEL .2. FIELD WATER-FLOW

Part I of this paper presented a two-dimensional dynamic finite-element model of fluid flow and solute transport in root-soil profiles with different root-uptake mechanisms. Field data collected in 1989 were used to validate the model. The present paper presents further validation and application of the numerical solution of Richard's equation against the field data collected from an agroforestry demonstration site for sustainable agriculture during the 1990 irrigation season. The site is tile-drained, isolated from the surroundings by interceptor drains, planted with six-year-old Eucalyptus camaldulensis (red gum) over an area of shallow ground water, and irrigated by a furrow system. Computer simulations were made for 220 dayas to evaluate the irrigation management. In comparing the measured with the numerically predicted volumetric moisture content in the soil profile and pressure head, the values were well correlated in space and time (r = 0.82-0.94). Therefore, the model can be used to provide management guidelines for subsurface drainage in agroforestry systems.