AbstractThe objective of the KFKI project BELAWATT was to answer the question: How much are the spatial patterns of sediment and benthos in the Hörnum tidal basin (German Bight, North Sea) influenced by hydraulic impact (currents, waves)? The bed shear stress, calculated from a simulated 2-years time-series of currents and waves (product of BELAWATT) was tested as a potential parameter influencing the spatial sediment pattern. The sediment data consisted of the median values of measured grain-size distributions. The comparison of shear stresses with sediment data showed: the distribution of sediment is highly correlated with bed shear stresses, but the explained variance is (with 10 to 20 %) not sufficient to allow the forecast of the sediment regime in the Hörnum tidal basin as a result of changing hydrodynamic conditions. The potential physical parameters influencing the spatial benthos distribution in the Hörnum tidal basin were the bed shear stress, the duration of subaerial exposure of tidal flats and the median grain-size of bottom sediments. Linking the spatial benthos patterns to the physical variables shows: the spatial patterns of benthos data and of physical variables in the Hörnum tidal basin are highly correlated, but the explained variance is 25 % at best. The explained variances are not sufficiently high to forecast the future development of benthic communities as a result of changing physical variables.