UNGAUGED CATCHMENT MODELING .2. UTILIZATION OF HYDRAULIC MODELS FOR VALIDATION

A two dimensional finite element model, RMA-2, is applied to a 25 km floodplain reach in West Germany. This scheme is shown to be capable of providing a good predictive capability over the comparatively long reach length. In addition, when the scheme is driven by an input hydrograph generated by an ungauged flood forecasting scheme (HYMO3), the results remain encouraging in terms of both outflow hydrograph and downstream stage prediction. These initial results are supportive of the possibility of large scale applications of finite element schemes providing base (or 'ground truth') discharge data for ungauged catchment model validation, where no downstream gauged flow records are available. Secondly, such schemes can themselves be driven by ungauged semi-lumped forecasting models to provide an improved resolution of inundation and flow characteristics, (including velocity vectors) in those reaches where such data are required.