Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(13) in Table I, while the comparison of observed and corrected stages with those estimated on the basis of different frequencies of recurrence are shown in Table IV for the Bezdán gage in the boundary of the country. BRIEF PUBLICATIONS AND REPORTS 1. Gál, T. and Némethi], L., Civ. Engrs. : Experiences with automatic headwatercontrol gates (for the Hungarian text see pp. 99) The equipment designed and constructed after data published in the literature on the headwater-control device manufactured by the French firm Neyrpic failed to operate properly under the particular set of conditions, in that it could not be adjusted to maintain the preset level within an error of ± 5 cm regardless of discharge. The modified headwater-control gate ( Figs. 3 and 5) installed first in the lieadworks of the K-V reservoir, differs from the Neyrpic type in the following features: a

) The float has been replaced by two, mounted on each side of the gates. b

) The cross-sectional area of the floats has been roughly doubled. A gap of no more than 2.5 cm has been left between the floats and the wall of the float chamber, which communicates with headwater through an opening of 14 mm diameter. The modified device was found to operate with an error of less than ± 3 cm and to be unaffected by discharge within the entire range of conveyance. Separate oscillation dampers proved superfluous, since damping was perfect. Interference between two gates was not observed even in the case of twin devices. However, owing to the high degree of damping, the device responds rather slowly, so that in the case of sudden changes in water level the accuracy of regulation is disturbed for a period. For this reason it is recommended for installation in locations where sudden level changes are not anticipated (flat irrigation canals in plain areas). Balancing is simplified by spindles mounted on the first counterweight-container, on which steel discs can be suspended as additional counterweights. From the rather small number of discharge measurements performed with the device the following conclusions could be arrived at: — the conveyance capacity of the gate is smaller than that estimated using the diagram published in the catalogue of Neyrpic (Fig. 6), — the limit of downstream submergence is about 50 cm and thus slightly higher than the figure quoted in the catalogue ( Fig. 8), — at a differential head Л = 50 cm the discharge is approximately in direct proportion with gate opening (Fig. 9). 2. Dr. Iviesies, L., Civ. Engr. : Determination of obligatory open strips ou the levee foreshores (for the Hungarian text see pp. Ill) An order has been issued by the Hungarian Minister of Food and Agriculture concerning the use of inundation areas between the flood levees, with provisions on the strips to be maintained free. In order to determine the shape and dimensions of the obligatory open strips air-flow and hydraulic models have been constructed to the scale 1:2880 of a 20 km long reach of the Hungarian lower Danube (downstream of Baja). Five different layouts have been studied (Fig. 1 ). The arrangement shown in Fig. 2 proved to be most favourable in contrast to the present situation (Fig. 3). Studies in similar models are recommended for determining flow conditions at highwater on other reaches of the Danube and other watercourses of Hungary. 3. Papfalvg, F. : Experiences gained with nuclear density- and moisture measurements in hydraulic engineering (for the Hungarian text see pp. 117) Nuclear devices for density- and moisture measurement have become increasingly popular since 1964 in hydraulic engineering in Hungary [1], [2j. For checking the density attained during the construction of earth structures the surface probe developed at the Railroad Research Institute is used. On one construction project