Floodplain wetlands rely on catchment flows to maintain the flooding cycles critical to their ecological integrity. The development of water resources has significantly altered the flow patterns in many river systems. Recent research into water requirements for wetland systems shows that duration, frequency, depth, timing and extent of flooding are the most important influences on ecological communities. Modelling these systems is hampered by a lack of data and inappropriate model structures. Remote sensing using AVHRR satellite data were shown to be an effective option for assessing flood dynamics. Vegetation communities and flood patterns of the Gwydir floodplainwere analysed to provide a model structure based on channel, flowpath and core wetland components. The temporal and spatial behaviour of each component was described using water balance principles. The model was calibrated and tested under a range of climatic conditions and the results demonstrate that the model can simulate ecologically significant flood dynamics of the floodplain wetland. This study demonstrates that a conceptually based, semi-distributed water balance approach can provide the basis for an effective decision support system for water management.