By Hendrosusanto, J. Feyen, W. Dierickx and G. Wyseure

On Third International Workshop on Land Drainage

This paper aims to verify if the water table fluctuation in a shallow drained field can be predicted through simulation. A number of models where thus analyzed and simulated water table evaluations compared with observed values to evaluated the performance of the models. The models used where the ‘de Zeeuw-Hellinga’ (1960) formulae, the SWATRER (Belmans et al., 1983) and the DRAINMOD (Skaggs, 1980) models. The experimental data used for the parameter estimation, and the validation were derived from a field drainage set-up. The site is pasture land, on a sandy loam soil in the province of west Flanders. Field drainage base is 70 cm below the surface with a drain spacing of 8.3 m. 50 mm OD collector ditch. In the plots used for model validation, laterals trench was treated with or without a coconut fibre mat, and the backfill of the trench was treated with or without polyacrilamide. The results revealed the for the given period and conditions, the DRAINMOD model performs considerably better than the SWATRER model in the prediction of the water table depth and drain outflow. The simplified formulae of ‘de Zeeuw-Hellinga’ predicts fairly well the water table head, but is less performant in calculating drain outflow. Neither of the tested models are capable in quantifying the effect of the drainage treatment (difference in applied entrance resistance) on the water table fluctuation and drain outflow.