The project 'OMES' has reached a first halt. Final reports of partial projects have been presented. A lot of knowledge about processes within the biogeochemical cycle of C and N, about the role of vegetation, benthos, sedimentation etc. on the estuarine ecology has been built up. Nevertheless an integrated view comprising all the separate projects is still lacking. The aim of this project is to present this integrated approach. First a thorough investigation of the water quality is essential as background knowledge. Therefore all suitable data will be assembled in a data set. This set will then be enlarged by the results of a datasonde which is measuring from 1996 on. All these data will then be coupled with data of the tide. Tidal cycles will be carried out in order to quantify tidal variations. All final reports will be submitted to thorough study in combination with literature study. Relations and hypotheses will be put forward. Through extrapolation of the data set statements will be made about the past, the present and the future of the estuarine system.