The paper presents a robust Darcy-based one-dimensional soil water balance model (SAWAH) for simulating riceland hydrology. Experimental data from an upland rice toposequence showing highly variable groundwater and volumetric soil water contents &thgr; are used to calibrate the model and to validate it by a modified cross-validation method. Analysis of variance is applied to estimate the mean squared prediction error and to split it into errors in predicting horizontal, vertical, and temporal gradients of &thgr;. Root mean squared error of prediction (RMSEP) of soil water content at strip-depth-time points was about equal to the standard deviation of unreplicated measurements. Measured strip and field means were more accurate than predicted means, but RMSEP remained below 0.03 m3 m-3. Ranking of crop and soil parameters for their effects on root zone water content and seasonal flux totals depended strongly on the imposed hydrology regime. Capillary rise contributed 5--55% of seasonal evapotranspiration, depending on season and topographic position. ¿ American Geophysical Union 1995