Evaluation of vertical and lateral flow through agricultural loessial hillslopes using a two-dimensional computer simulation model

On four hill-slopes in the loess region of the Netherlands pressure heads were monitored during rain events with time intervals of five minutes. Water flow through these hill-slopes during erosive rain events in summer and winter was simulated two-dimensionally. These simulations showed that vertical flow is dominant during rain events, whereas lateral water transport is of minor importance. The average lateral water movement varied between 1.6 and 4.7% of the total water displacement. Therefore, it was decided to incorporate a one-dimensional water flow module into the soil erosion and hydrological model LISEM.