Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

lateral branch system for improving the main channel. The second paper contains a report on a new method of regulating a shallow section of the main Danube channel. In a remarkable paper Valtyni [13] suggested methods of regulation corresponding to the natural character for the improvement of torrents. The basic concept underlying his approach is that the bed of the torrent is on the one hand deformed by erosion, on the other, it is at the same time stabilized by a natural process. By allowance for this twofold effect considerable success has been attained. 2. Problems relating to construction Viewed in the absolute sense river regulations are very expensive. The material used for such purposes — rock in most countries — is a very expensive building material. Several problems are encountered also in the use of mechanical equipment. The development both in the use of building materials and construction technology has been so far a slow one. It is for this reason that great attention is due to the — alas — small number of papers describing new methods. In the paper by Herheulidze [6] one-, two- and three stage lattice, structures are described, for which no more than four different types of prefabricated unit are used. The advantages of using this type of structure include savings in cost, small dimensions of standardized elements, ease of erection and reliable performance. In the paper by Valtyni [13] the use of ramps constructed of large boulders instead of the conventional bottom drops for controlling torrents is described. More recently semi-permeable timber groynes were also applied successfully, while sediment producing sections were stabilized by natural vegetation. 3. Studies into problems of economics As mentioned in a paper by Szilágyi, the analysis of economic problems related to the complex and manifold activity of river regulation is usually omitted. True, these problems are not accessible to simple methods of economic analysis. From among the papers submitted, that of S. Ress [11] is devoted to the economic aspects of river regulation. Coupled with the engineering research aimed at the elaboration of new concepts in river regulation, the study of economic problems has also been started at the Research Institute, as has been done in connection with other branches of water management. The objective of this work was — as defined in the paper by Ress himself — the development of a decision making model system for the whole of a particular river. The general social criterion that the highest possible benefits should be realized at the lowest possible cost, assumes different aspects when applied to river regulation. This is due to the open character of the activity, its close interrelations with Nature, 2 33