Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

prepared as sediment scales, the diameters of which correspond to the limit dimensions of individual size fractions. The particles are classified into fractions by comparing the standard discs and the photographed area of the particles. The method was checked by taking several photographs of sediment material of known gradation and by analysing these photographs. The grain size distribution curves obtained by the two methods differred by no more than + 10%. In river surveys photographs are taken at times of low stages, when much of the bed is exposed. An unquestionable advantage of the method is the minimum of field work and the elimination of the considerable volume of work associated with the taking, handling and transportation of samples as well as with their sieve analysis. However, practical data on the time and labour requirements for the evaluation part of the photographic method would also be of great interest. Conclusions From the introduction and the papers reviewed in the report it will be appreciated that in spite of the tremendous efforts spent all over the world for sediment transportation research, the number of uncleared problems in this field is still considerable. In fact, the deeper these questions are probed into, the more involved the relationships tend to become and increasing difficulties are encountered in their exploration, exact definition and mathematical formulation. The organization of symposia and conferences similar to the present one, as well as the establishing of close personal contact between investigators engaged in this problem should for this reason be considered as of paramount importance. Great importance should be attributed further to field observations and measurements on sediment transportation phenomena, first of all on experimental river sections, to the coordinated performance of field and laboratory studies and to the intensive development and improvement of the necessary observation instruments and methods. PAPERS REVIEWED IN THE REPORT 1. Bogárdi, J. L.: The critical mean velocity, as a characteristic for the incipient movement of bed-load (in English) 2. Bozinovic, M. : Bed-load observations on the Drava river (in English) 3. Burz, J.: Problems in sediment transportation formulae (in German) 4. Hankó, Z.: On the critical mean velocity starting bed-load movement (in German) 5. Hartke,H., Mauersberger, P.: Observation of sediment movement in rivers, lakes, on the coast, using magnetic indicators (in German) 6. Egiazaroff, I.: Torrents, the possibilities for their theoretical analysis and modelling at the laboratory (in English) 7. Romanovskyi, V. V.: Photographic method of analysis of the grain-size distribution of coarse bed-load (in Russian) 58