G.T. Csanady - Böcker

The rather excessive public preoccupation of the immediate past with what has been labeled the 'environmental crisis' is now fortunately being replaced by a more sus­ tained and rational concern with pollution problems by public administrators, engineers, and scientists. It is to be expected that members of the engineering profes­ sion will in the future widely be called upon to design disposal systems for gaseous and liquid wastes which meet strict pollution control regulations and to advise on possible improvements to existing systems of this kind. The engineering decisions involved will have to be based on reasonably accurate quantitative predictions of the effects of pollutants introduced into the atmosphere, ocean, lakes and rivers. A key input for such calculations comes from the theory of turbulent diffusion, which enables the prediction of the concentrations in which pollutants may be found in the neighborhood of a release duct, such as a chimney or a sewage outfall. Indeed the role of diffusion theory in pollution prediction may be likened to the role of applied mechanics (,strength of materials') in the design of structures for adequate strength. At least a certain group of engineers will have to be proficient in applying this particular branch of science to practical problems. At present, training in the theory of turbulent diffusion is available only at the gra­ duate level and then only in a very few places.

For some time there has existed an extensive theoretical literature relating to tides on continental shelves and also to the behavior of estuaries. Much less attention was traditionally paid to the dynamics of longer term, larger scale motions (those which are usually described as circulation') over continental shelves or in enclosed shallow seas such as the North American Great Lakes. This is no longer the case: spurred on by other disciplines, notably biological oceanography, and by public concern with the environment, the physical science of the coastal ocean has made giant strides during the last two decades or so. Today, it is probably fair to say that coastal ocean physics has come of age as a deduc­ tive quantitative science. A well developed body of theoretical models exist, based on the equations of fluid motion, which have been related to observed currents, sea level variations, water properties, etc. Quantitative parameters required in using the models to predict e.g. the effects of wind or of freshwater influx on coastal currents can be estimated within reasonable bounds of error. While much remains to be learned, and many exciting discoveries presumably await us in the future, the time seems appropriate to summarize those aspects of coastal ocean dynamics relevant to 'circulation' or long­ term motion.