When modelling groundwater behaviour in wetlands, there are specific problems related to the presence of open water in small-sized mosaic patterns. A simple quasi two-dimensional model to predict water level fluctuations in partially inundated wetlands is presented. In this model, the ratio between inundated and non-inundated areas provides an adequate description of water storage properties. This concept can be implemented in any hydrological model. Two examples of such an implementation in the soil water flow model SWATRE are presented in this paper. (C) 1997 Elsevier Science B.V.