The FIELD_AC project aims at providing an improved operational service for coastal areas and at generating added value for shelf and regional scale predictions. Coastal-zone oceanographic predictions seldom appraise the land discharge as a boundary condition. River fluxes are sometimes considered, but neglecting their 3D character, while the "distributed" continental run-off is not taken into consideration. Moreover, many coastal scale processes, particularly those relevant in geographically restricted domains (coast with harbors or river mouth areas), are not well parametrized in present simulations. Work package 3 dedicated to Boundary Fluxes aims to establish and use the best possible boundary conditions for coastal water quality modelling. On this scale, all boundaries become important. For the land boundary side the needed products are distributed and point wise run-off both quantitatively and qualitatively. For the offshore boundary condition, 3D current, water quality field, and wave spectra will be used. For the atmospheric boundary, products from local scale meteorological models (wind, atmospheric pressure and rainfall) are needed. For the seabed, boundary information on sediment composition, bedforms and bathymetry and bio-geo-chemical parameters is essential. This report addresses the impact assessment for improvements in the four boundary conditions (boundary fluxes from land, free-surface boundary condition, seabed boundary condition and open boundary fluxes) on coastal hydrodynamics and particulate transport. The description of the improved four boundary conditions is followed by examples of concrete impact assessment of the theory into the Catalan coast, Liverpool Bay, German Bight and Gulf of Venice.