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of application typical of low and high pressure irrigation systems.
Their model also simulated post-infiltration redistribution.
Rubin (1968) developed a two-dimensional numerical model of
transient water flow in unsaturated and partly unsaturated soils. He
utilized alternating-direction implicit (ADI) finite difference methods.
He studied horizontal infiltration and ditch drainage with the numerical
model. Hornberger et al. (1969) developed a two-dimensional model
to study water movement in a composite soil moisture groundwater system.
They modeled the two-dimensional response of falling water tables. They
considered both saturated and unsaturated zones in their model. The
solution method used was a Gauss-Sidel iterative technique.
A two-dimensional model to simulate the drawdown in a pumped
unconfined aquifer was developed by Taylor and Luthin (1969). The model
gave simultaneous solutions in both the saturated and unsaturated zones.
They used a Gauss-Sidel iterative method to solve the flow equations.
Amerman (1969) developed two-dimensional numerical models to
simulate steady state saturated flow, drainage and furrow irrigation.
He used ADI methods to solve both the steady state saturated flow model
and the furrow irrigation model. He also used an explicit method to
solve the drainage model.
A study of the sensivity of the grid spacing for finite difference
models was reported on by Amerman and Monke (1977). Two finite
difference models of two-dimensional infiltration were analyzed. They
solved the two-dimensional flow equations with successive overrelaxation
(SOR) and alternating direction implicit (ADI) methods. They found that
smaller grid sizes were needed in regions where the hydraulic gradients