Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

present mostly problems of a practical nature, whereas the results obtained in the theory of sediment transportation are in many respects of theoretical significance only. The development of a closer correlation is retarded also by the circumstance that even the theoretical results which could be generalized in principle are of little direct practical value because of usually different local conditions. On the other hand, experiences gained on a given watercourse apply to the particular watercourse only and are without a proper theoretical foundation. For the lack of correlation between the practical methods of river regulation and theoretical results, the responsibility does not rest with the research workers only. The engineers engaged in river regulation frequently reject without justification the application of theoretical advances. Instead, they are inclined to experimentation within the prototype itself. Yet in river regulation, prototype studies may involve considerable expenditure — to mention only the construction of spur-, or parallel dikes — which could be obviated by a minor theoretical study or experiment, the costs of which are only a fraction of the former. It is encouraging to note that the theoretical aspects of sediment transportation and the practical consequences thereof in river regulation are gaining increasing attention, and continuous research is being conducted all over the world by investigators aided by modern technology, experimental, observation and data processing equipment. River regulation and the attendant sediment transportation phenomena are studied to-day from a wide variety of aspects. In these investigations three main trends can be distinguished. First of all considerable efforts are made to include the hydrological •properties and factors in the relationships describing sediment transportation in watercourses. The second trend is to extend the studies into bed morphology to the macro-, mezo- and micro-configurations, including also their effects on river regulation methods and on sediment transportation. The third main trend of investigations is towards the comparison of theoretical results with the data of measurements and observations performed in the field. In connection with the first trend of studies it should be noted that hydrological factors and properties are characteristic mainly for the origin of sediment in the catchment area and its entrance into the channel. Moreover, owing to their influence on the streamflow regime, they affect also sediment phenomena within the channel. The influence of hydrological factors on sediment transportation is a highly complex one. In many instances this influence can be demonstrated in a qualitative manner only, although there are some factors which can be related numerically with sediment transportation. The second trend comprises investigations on the shape, magnitude and movement of irregularities encountered in the bed of alluvial rivers. 24