Hidrológiai Közlöny 1947 (27. évfolyam)

9-12. szám - ÉRTEKEZÉSEK - LUKÁCS ANDOR: A körösvölgyi öntözések vízrajzi szempontból

146 HIDROLÓGIAI KÖZLÖNY XXVII: év!. 191,7. 9—12. száth. RÉSUMÉS FRANCA1S - BRIEF SUMMARiES - RIASSUNTI ITALIAN! KURZE AUSZUGE Suspended silt concentration. By Doz. Dr. J. Bogárdi. (Hungárián text with figs. and tables on p. 117.) B. C. 627.157 One of the important manifestation in the life of streams is the sediment transportation. The sediment moves partly rolling on the bottom, and partly suspended in the water. The significance of the suspended silt is sliown by the extreme values given on the authority of Lane in Table I. The quantity of the suspended silt is characterized by the concentration C (gr/m

:

l). If the water discharge of the river is Q (m^/sec), the moved silt load is equal to CQ. i The particles are kept in suspension against the gravity by the turbulence. The foregoing is reviewed by the author on the basis of the interpretations of Prof. A. A. Kalinske. In the state of equilibrium the condition is characterized by formula (1) in which w a signifies the settling velocity of the silt particles öf agivensize, „ the density of the water, m the water depth, and í the so-called mixing coefficient. On the left hand side of the equation the rate of the silt settling as a result of the gravity in unit time is stated, and on the right hand side is shown the amount of silt characterized by the product of the so-called diffusion coefficient and the negative gradient of concentration (O'Brien). The momentum transfer between the two layers is characterized by the shearing force t = ? u z, where ~z is the mean velocity fluctuation in the main direction, and u is that in the verticai direction. By expressing the foregoing according to fig. 1., we arrive at formula (2), and by taking intő account formula (3), formula (l'J, gives us, in case of u verticai velocity fluctuation and / mixing length, the rate of the silt transfer between the two layers. In taking into account fig. 2, (If) stands for variation of the concentration according to the depth, in which C„ denotes the concentration due to the maximum velocity. If therefore we determine at a single point of a vertitíal the concentration by measurements the amount of the suspended silt may be computed. The author submits herewith measurements taken at Rázompuszta on the Tisza (fig. 3.J. With the aid of (5) of the velo1 city curve we may compute £ and — curve The area m 8 of the latter curve is | —and

1 therefore in possession o of the measuring data C

0 we arrive with the aid of (-',) at the concentration curve. (In the figure besides the computed values the measured values are alsó shown. The author refrains at this time from discussing the causes of deviations). The figure compiled from the vC products show the average concentration prevailing in the verticai (vC) ^ and if we proceed on more verticals we arrive according to (6) at the silt load passing over the whole cross section. Table II. summarizes the results of the measurements performed on the Tisza in the years 1942 to 1944 at Záhony and Rázompuszta. The measurements were performed with a new, very simple but reliable sampler. According to the results the concentration on the Tisza is considerably less than would answer the hydraulic factors. It is, naturally an effort to determine the amount of the suspended siít without measurements with simpler, direct methods with the aid of the hydraulic characteristics of the river bed. According to investigations made by Lane and Kalinske there is under equilibrium conditions of the river bed a proportionality between the concentration of suspended material at the bed C; characterized by the fali velocity <", and the concentration of this material in the bed Cf. The proportionality is expressed in function (1), where t

0 denotes the bottom-shear. It's value is given on broad, natural river beds by formulas (8) and (8'), in which y is the specific gravity of water, I the slope and h the totál water depth. I /? , the so-called „friction velocity" in function (1) depends on the hydraulic properties of the stream only, and therefore seems to characterize the ability of the turbulence to pick sediment off the bottom. At the same time <•> is characteristic of the partiele size. Function (7) is not yet determined by laboratory measurements; data derived from actual measurements (which, of course, are not homogeneous) give the curve shown on fig. 5. expressing the equiübrium conditions. The points of the measurements above the curve denote settling those below the curve scouring. In accordance with more recent researches by Kalinske and Hsia the viscosity must alsó be taken into account in a manner not considered in the previus investigations expressed by function (9) and (9'J respectively (d — particle-diameter, v = cinematic viscosity). The latter function is shown in fig. 6. With the aid of this the concentration C/ may be computed from the hydraulic data and thus it can be determined from the outset whether in a certain section settling below the curve scouring. The number of measurements are too few so far, and therefore fig. 6. cannot be considered a final result as yet. Newertheiess it is encouraging and characteristic, especially in view of the investigations by Kalinske that the revealing of one of the most complicated phenomenon of streams is going ahead in the right direction. M Captage d'une source karstique á Diósgyőr (Montagne de Bükk, Hongrie du Nord). Par K.Balogh, Deur és Sc. (Texte hongrois, carte, tableaux et figures p. 124.) D. C. 551.49:628.1) A propos des travaux de captation de la source „Tavi" l'auteur expose les relations géologiques et hydrogéologiques du groupe des sources thermales de Diósgyőr. Au fond des sources de Diósgyőr („Szent György", „Boldogasszony" et „Tapolca" 22° C, „Várárki" et „Tavi" 17° C) s'éléve un massif contitué des porphyroides; schistes et calcaires gris alternarut—les derniers contiennent parfois du silex —• (étage de Campil); calcaires claires stratifiés (Trias moyen); calcaires gris