Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(12) PRINCIPLES FOR DESIGNING IRRIGATION ON THE DEBRECEN LOESS PLATEAU By MM, J. and Kvasz, J., Civ. Engrs. (For the Hungarian text see pp. 71) Conditions favourable for irrigation agriculture exist on the Debrecen loess plateau in the eastern part of Hungary, in the range of the Tiszalök irrigation project. Owing to great distance from, and differential elevation relative to, the point of diversion, investment costs for up-to-date sprinkler irrigation would be high, so that in the interest of an economical solution it was found necessary to revise conventional irrigation policies. The principles for designing irrigation farming on the loess plateau were established by the authors in the following manner: For meeting the demands of agricultural operations—and for extending irrigation to an as large as possible an area —it was necessary to establish the prerequisites for irrigation and to ensure the optimum utilization of irrigation water in order to attain the highest benefit-cost ratio. Starting from these principles the design rate of application within the system has been set at 0.26 to 0.29 lit/sec per hectare. Hereafter the following design features are outlined: a

) Conveyance of large volumes of irrigation water over large distances through pipelines made of large-diameter pressure pipes of plastics, or r.c. concrete. b

) For the distribution of irrigation water in the irrigation section rapid-coupling pipes of aluminium, further secondary- and lateral lines of flexible, high-pressure plastic-fibre hoses are envisaged. The theoretical model of a sprinkler irrigation section of 10,800 hectares total area and composed of 288 plots of 37.5 hectares each is then described and five alternatives are evaluated in the light of the level of development established and the new materials suggested for introduction by them. Engineering designs are accompanied by economic analyses. THE DETERMINATION OF DESIGN FLOOD STAGES FOR THE REINFORCEMENT OF THE FLOOD LEVEES ALONG THE YOUGOSLAVIAN REACH OF THE DANUBE AFTER THE 1965 FLOOD by Chahun, K. Civ. Engr. (For the Hungarian text see pp. 89) Construction work on the reinforcement of the flood levees along the Yugoslavian Danube reach immediately downstream from Hungary has been started in 1966. A fundamental problem in designing the new cross sections, namely the determination of the design flood stages is described in the present paper. The first essential step consisted of correcting the stages of the 1965 great flood along the Yugoslavian reach —down to the mouth of the Tisza River. This was performed on the basis of strcamflow rates, in order to eliminate the influence of levee ruptures in 1965, the flood hydrograph on the majority of gages having been distorted by these ( Fig. 2). Considerations are centered around two problems, namely the influence of the levee rupture at Kamariste, downstream of the mouth of the Dráva River, on flood levels and on this basis the correction of flood stages, the second comprising the estimation—relying on the corrected stages —of flood stages with different frequency of recurrence. Highest stages actually observed in 1965 and the corrected ones were found to be higher than those of 1000 and 10,000 years frequency of recurrence estimated without the 1965 flood (Table II). Estimates including the highest stages of 1965 indicate however, that floods similar to that in 1965 must not be excluded from the design (Table IV). Highest stages observed before 1965 on different gages, the observed and corrected stages for 1965 and the differences of these values have been compiled