These proceedings contain the papers presented at the Fourth International Conference on Finite Elements in Water Resources, held in June, 1982, at the University of Hannover, Federal Re public of Germany. This Conference continued the successful series of previous conferences held at Princeton University in 1976, at Imperial College in 1978, and at the University of Mississippi in 1980. Since Finite Elements have proved to be a powerful means for analysing water resource problems, the principal objective of the Conference was to provide an exchange of experiences in practical applications of the finite element method and to establish a forum for discussion regarding accuracy, economy, limitations and improvements. Related discretization methods were included within the scope of the Conference. New develop ments in numerical and computational techniques, basic mathe matical formulations, and soft- and hardware aspects were considered to be equally important topics for an exchange of ideas between both theoretically and practically oriented re searchers. The Conference Organizing Committee is very grateful to the many distinguished scientists who attended the Conference, and for their contributions towards the proceedings. This collection of papers in being made available to a wider audience of en gineers and scientists by CML Publications in Southampton, U.K.

Numerical simulations are in world wide use for the investigation of hydro- and thermodynamic processes in natural waters. In spite of the fact that great achievements have been brought about in this field, numerous questions still remain unanswered, with respect to fundamental formulations as well as to methods of solu- tion. One of the principal objectives of research in our days is the verification of numerical models. The Symposium on "Mathematical Modelling in Estuarine PhysiCS" was held at Hamburg, Aug. 24 - 26, 1978, with the objective of for- mulating the present standing of research work and of the most im- portant problems in this field. Aspects of physical oceanography and of coastal engineering were to be considered. Estuarine phys- ics were a suitable topic as both disciplines have many points in common there. Eighty-five scientists from sixteen countries convened for two and a half days to discuss details with much interest. We wish to thank them as well as the authors for their contributions. Further, we wish to express our gratitude to the German Research Foundation (Deutsche Forschungsgemeinschaft), Bonn-Bad Godesberg, to the Special Research Project 79 "Research in Coastal Waters" (Sonder- forschungsbereich 79 "Wasserforschung im Klistenbereich"), and to the German Hydrographic Institute (Deutsches Hydrographisches Institut), Hamburg, for sponsoring the meeting and for helping with the organization.