WATEM is spatially distributed model to simulate erosion and deposition by water and tillage processes in a two-dimensional landscape. Unlike more sophisticated dynamic models (e.g. WEPP or EUROSEM), WATEM focusses on the spatial, and less the temporal, variability of relevant parameters. As such, WATEM allows the incorporation of landscape structure or the spatial organization of different land units and the connectivity between them. In order to avoid major problems with respect to the spatial variability of parameter values and uncertainty of parameter estimates, WATEM is a simple topograhpy-driven model. The water component of WATEM uses an adapted version of the Revised Universal Soil loss equation (RUSLE) since (approximate) parameter values are readily available for many areas. Recent studies have recognized the relevance of direct soil movement by tillage for soil erosion on agricultural land. The tillage component of WATEM uses a diffusion-type equation whereby the intensity of the tillage process is described by one parameter (tillage transport coefficient or ktil-value). ktil-values for different implements can be found in literature (Govers et. al 1994).

WATEM can be used to estimate/evaluate:

• water erosion/deposition rates and patterns
• tillage erosion/deposition rates and patterns
• combined effect of water and tillage erosion
• the effect of changes in landscape structure on water and tillage erosion