Vízügyi Közlemények, 1965 (47. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

<123) The conventional methods of flow measurement using a revolving type current meter fail in general to yield immediate results, due primarily to the lengthy computations involved. The flow is difficult to determine on the site. Applying an approximately uniform distribution of observation points (in large cross sections in verticals, in small ones in horizons) and with observation periods of 50 seconds at each point all revolutions measured in the vertical are integrated with the help of an integrating instrument. The average r. p. m. is determined therefrom and the corresponding mean velocity is read directly off the rating curve. The time required for computation can thus be reduced from several hours to 10—15 minutes, and the staff engaged in computation work can be from 1/5 —1/10-th of that engaged in actual measurement. For illustrating the method results of observations (Fig. 3 ) carried out under rather adverse conditions in an experimental flume (Fig. 1) using an Ott Minor type component vane revolving current meter are given. The relative scatter of flow measurements was 3.34%, which can be considered very satisfactory under prevailing conditions. The method described is recommended primarily for scries of observations. Hamvas, F., Engr. : Variations of uplift at the Tiszalök Barrage. (For t lie Hungarian text see pp. 566) The objective of piezometer tubes installed in the structures of the Tiszalök Barrage and groundwater observation wells sunk in its surroundings (Fig. 1 ) was to enable prediction of situations endangering its stability, and a comparison of experimental and theoretical data with actual observations. Design computations were made using the Warren—Weaver method modified by Khosla (Fig. 2), while a hydraulic model to scale 1 : 50, as well as electric analogy was used for the experiments. When attempting any comparison with actual observation data, it should be borne in mind, that two-dimensional steady conditions were assumed during the experiments, whereas actual seepage is of a non-steady character. Observation data were therefore processed by correlation calculation according to methods of mathematical statistics, for which an example is given in Table I. Correlation lines are shown in Fig. 3, while theoretical and actual hydrodynamic pressures are illustrated in Fig. 4. Actual pressure values are lower than, and gradients paractically identical to, calculated ones. In the vicinity of the curves variations of groundwater level closely follows stage variations, as demonstrated in Fig. 5. Perényi, К., Engr. : Irrigation in Svria. (For the Hungarian text see pp. 572) The importance of irrigation in Syria is due to the non-uniform distribution of precipitation over the year and over the country (Fig. 1 ). The annual discharge of rivers and springs can be estimated at 10

9 cu.m, of which 80° 0 is conveyed by the Euphrate River. Subsurface waters originate from cretaceous layers. A plan was prepared for the development of irrigation, the 8 most important systems of which are denoted by numerals in Fig. 3. It is intended to increase irrigated areas to a total of 889 000 hectares. Data of main irrigation systems contemplated are demonstrated with the help of photographs taken on the site. REVIEW 1. Earlli «Orks in hydraulic engineering with conventional and nuclear blasting Beviewed after Graves, I., Mágnáson, G. and Vor

/man, I. by Ivicsics, F. (For the Hungarian text see pp. 584) After a review of conventional blasting methods a description is given of plans relating to the new navigable canal in Central-America. Nuclear blasting offers an economical method for constructing the canal and extensive tests have been carried out in the United States to determine effectiveness of this method. Problems of shock waves in the soil and radioactive pollution due to nuclear explosion were also considered.