Vízügyi Közlemények, 1966 (48. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(46) bij = regression coefficient representing the relationship between water and crop, calculated for individual periods (months) from data relating to the series of years "j" which characterize the standard "j" of farming [q/ha, mm]; Xjj — waterhousehold coefficient of the area under consideration during the series of years "j", related to the upper extreme value attainable by the standard of farming during the same years ; Q

k = average crop over area utilized by growing plant "k" during the series of years under consideration [q/ha]; gk = ratio for expressing crop of plant "k" in corn units fk = ratio of area over which plant "k" is grown; Xjj = waterhousehold coefficient of artificial interference, or structure during the series of years "j" related to the upper extreme value attainable by the standard of farming during the same years ; e

i

r = periodical (monthly) reduced deficiency, or surplus of water [mm] in the model characterizing waterhousehold, the reducing effect on the crop of which was averted by the interference, or structure. DESIGN OF BED REACHES IN UPSTREAM CONTROLLED SYSTEMS OF IRRIGATION CANALS By Dr. Z. Szigijártó, Engr. (For the Hungarian text see pp. 216) The objective of this paper is the determination of principles and considerations to be observed in designing bed reaches of systems of irrigation canals controlled from upstream. The concept of designing bed reaches is dealt with first in Section I. The objective thereof is designated as the determination of hydraulic parameters governing the dimensions of surface regulating sluices, the canal, diversions, spillways and overflows, on the basis of economic considerations. Section II is devoted to the more detailed analysis of problems relating to hydraulic design. Sub-section 1 is concerned with the selection of type of surface regulating structures. Relying on theoretical considerations and practical experience the tilting-leaf type of weir is suggested for manually controlled structures, while under conditions prevailing at present in Hungary automatic surface regulating structures should be designed as vertical lift weirs. In calculating surface oscillations along the reach the accuracy of surface regulation should be allowed for, together with the range of surface fluctuations characteristic for accuracy. For automatic headwater regulators operating on the hydraulic principle this may be assumed as ±5 to 10 cm, while with manual control this value is — according to observations on the К. IV. system main canal — ±5 cm for tilting leaf weirs and ±7.5 cm for vertical lift designs. It is very important to note that the lowest possible position of the surface profile occurs, when at times of lowest demand on the reach the water level is maintained at the lower limit of the range of fluctuation by the regulating structure. Conversely, the highest position ensues in the case when the upper limit of the range is maintained at the time of greatest discharge (Fig. 1 ). As a last item in this group of problems, head losses caused by surface regulating structures are discussed together with the method suitable for taking these into account. In Sub-section 2 the design of intakes is discussed and the permissible range of surface fluctuations is determined. This problem is analysed in detail in connection