Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(30) considered first. Thereafter an approach from the side of flow conditions is followed by attempting to relate channel configurations to characteristic types of flow pattern. The objective is to predict the type of bed change once a pattern of flow is created by a particular engineering measure. Regardless of the approach adopted, Figs. 2 to 4 offer guidance in finding the corresponding channel configuration and flow pattern. Changes in channel configuration may be vertical and horizontal (Fig. 1). Vertical changes may be scouring [1] (Fig. 2), or filling [2] (Fig. 3), while horizontal changes may take the form of bank erosion [1], or the deposition of solids along the bank [2]. Characterizing for scouring processes is the concentration of flow lines. Examples for the concentration of flow lines in bed contractions, along concave banks and around groynes are shown by the examples 1, 2 and 3, respectively, in Fig. 2. Filling processes are characterized by two typical flow patterns, of which one is the wider spacing of flow

r lines (Fig. 3), the other being indicated by an area of back flow ( Fig. 4). Example 1 in Fig. 3 illustrates the divergence of flow lines at an inflow, Example 2 the wider spacing along convex banks in meandering watercourses, while Example 4 the dispersal of flow lines at hydroelectric stations. Back flow areas at upstream and downstream ends of lateral branches, downstream of sand bars and islands, along a convex bank, downstream of groynes, along levees and in the bay of power stations are illustrated in Examples 1 to 6, respectively, given in Fig. 4. The other large group of bed changes consists of horizontal changes, which may take the form of bank erosion and bank accretion. The flow pattern characteristic for the first is the concentration of flow lines, whereas a wider spacing is typical for the second. DIMENSIONING OF IRRIGATION STRUCTURES ON THE BASIS OF PLANT GROWING By Dr. J. Balogh, Agr. Engr. (For the Hungarian text see pp. 180) Problems related to the dimensioning of irrigation structures are dealt with from the aspects of plant growing and agricultural operations. The first part of the paper, comprising Chapters I and II, will be published in the present number, Vízügyi Közlemények, No. 2, 1970, while the Second, Chapter III in No. 3, 1970 of this journal. The principles and considerations suggested to observe in dimensioning are dealt with in the following Sequence: Chapter I on the area units of irrigation and plant growing, Chapter II, the dimensioning of irrigation structures according to the water demand of plant growing, and Chapter III concerned with the determination of the size and structure of irrigated farming, on the basis of available water supplies. Chapter I. The area units of plant growing are determined primarily by considerations of farming operations, then by natural conditions (topography, channels, watercourses, etc.) and finally by artificial features of the terrain (roads, canals, etc.). The basic requirement to be satisfied when staking out the area units is to ensure the possibility of mechanised working. It should be remembered further that the area units of plant growing should coincide with those of irrigation within the plots. The irrigation features controlling the length and width of plots are listed for different types of irrigation equipment in Table VI. Chapter II. In dealing with the dimensioning of irrigation structures distinctions are made depending on whether it is the main diversion, the system conveying, or distributing