Simulating 3-D water flow in subsurface drain trenches and surrounding soils in a clayey field

•Excavated drain trenches were studied with and without supplementary drains.•Fast water flow through drain trenches was simulated using a 3-D hydrological model.•One and two pore system model setups were used to study preferential flow.•Both models were suitable to describe the recorded drain discharge.•Heterogeneity of clay soil should be taken into account in model parameterization.