Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

According to Csoma every river forms a system tending towards dynamic equilibrium where a change in any of the factors affecting development necessarily involves changes in the others also. Dynamic equilibrium is disturbed by regulation, representing an artificial interference into this process, after which the river tends to reestablish conditions in accordance with its character. In the course of this reestablishment either the structures and results of artificial interference are eliminated, or a new condition of dynamic equilibrium is established under their influence. The primary objective of river regulation is believed to be the establishment of dynamic bed stability and the maintenance of dynamic equilibrium. The assumption that each river strives towards a condition of dynamic stability should be accepted as basically correct, since there exists a highly complex relationship between the hydraulic parameters, the rate of sediment transportation and the morphological factors of a watercourse. However, in natural rivers this equilibrium is rare and occurs then for relatively brief periods only. It should be remembered that considerable changes may occur even without human interference, as a consequence of the eternal changes of Nature, e.g. in the hydrological factors governing flow. Regulation may provide interference into the life of the river at the time and location, when and where the dynamic stability has been disturbed by such changes. In modern times various uses of water entailed a rapid increase in the number of human interference as a result of which some, or all of the parameters controlling the dynamic stability underwent changes of varying extent. The new aspect for river regulation is that the change in factors controlling dynamic stability occurs at a much higher rate than that of natural changes, and correspondingly regulation must be effected more rapidly and more effectively than before. In the solution of similar problems there is usually no imperative need for modifying existing regulation principles, or for establishing new ones, but owing to the increased rate of changes, and in the interest of improved effectiveness, in the solution of actual river regulation problems theory should be relied upon to a much higher extent and the role of practical experience becomes secondary. This trend of development is reflected also in the subjects selected for the papers submitted. Gergov [5] suggested the relationship В = G log (H + a) for describing the shape of the channel cross-section. Here В is the width and H the average depth of the channel. In the formula G and a are the indices of the transverse and vertical erosion of this bed, respectively, which describe the shape of the channel cross-section and represent the combined influence of hydrological, geological and other factors. In the paper the magnitudes of G and a are studied under different geological conditions, and by generalizing the results obtained the river channels are classified according to variations in the contourlines of the cross section and in the index G. 31