Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(11) The geological map of the surroundings of the principal Szinva-spring is shown in Fig. 1. The waterbearing formation supplying the spring is seen to be Triassic limestone rock the caverns and minor fissures of which form the network of passages for water. Originally the spring emerged at several points, the larger ones denoted by the numbers 1 to 3 in Fig. 2, showing the detailed layout of the spring development, while the minor ones in the ditch of the Eger —Lillafüred road shown in Fig. 3. The spring denoted by No. 3 flowed only at times of floods and acted as a relief spillway. The spring is seen to spill during the March flood in 1962 in Fig. 4. The development of these spirngs is described in 5 section. The geological structure of the catchment area, the morphological and geological origins of the springs are described in Section 1. A profile of the spring area, the left-hand side denoting North, the right-hand side South, is shown in Fig. 5, from which the limestone rock containing the water dearing passages is seen to stand vertically between the impervious rocks running to the North and South of the springs. Below the spring, on the northern side the limestone yielded under high pressure and folded slightly over the porphyrite forming the impervious sill (see Fig. 5, borehole No. 2). The spring emerges from the cavern system as a broadcrested weir over the porphyrite. The cavern passages are revealed also by the exploratory shaft illustrated in Fig. 6. Section 2 is devoted to the hydrology of the spring. Yields have been measured regularly from 1950, followed by detailed observations in the course of studies from 1962 to 1963. The yield-hydrograph, the integral-yield curve and the duration curve are reproduced in Fig. 8, based on these observations. It will be perceived from these that the yield oi' the Szinva spring can—to a certain extent —be described by the relationships applying to outflow from a vessel. The hydrology of the spring was found to be controlled decisively by precipitation in the Winter half-year. Once this was recognized, spring yields in Summer and early Autumn could be predicted. A log-log plot of the spate of the Szinva spring in April, 1962 is shown in Fig. 9, while a semi-logaritmic plot was used to indicate the reeeeding branch of the spate as shown in Fig. 10. The waterlevel in borehole No. 5 above the spring ( Fig. 5) has been plotted against yield in Fig. 11, representing essentially the rating curve of porphyrite weir, which can be expressed analytically as Q = 0.072 Л

16. Exploration work around the spring is described in Section 3. Explorations have been carried out with the aim of investigating the possibilities for concentrating the spring to a single outflow and for underground storage, for the first purpose explorations were started by sinking the boreholes shown in Fig. 5. From the borehole data the limestone and overlying debris of a few metres thickness was found to be rather impervious, solid and suited for driving a wet well, in which the drainage siphons have been accomodated (see Fig. 6). An account of constructional work associated with the development of the spring is given in Section 4. Drainage by gravity having been envisaged in the ultimate development, a drainage tunnel was driven to the wet well. The profile and typical cross-sections of the tunnel are shown in Figs. 12 and lő, respectively, the concrete weir constructed at the entrance of water to the network being illustrated, together with the pipe junctions in Fig. 16. The highwater overflow at spring No. 3. is to be seen in Fig. 18. A view of the completed structure as seen from the tunnel side (bearing No. 5) is presented in Fig. 19. Problems related to underground storage are considered in Section 5, the development of the Szinva spring being used to illustrate the depression of the spring sill and the blocking principle. It is concluded that in the case of the Szinva spring hourly peak demands could be met from underground storage by depression of the spring sill, but no extended storage be realized in this manner. Underground storage by blocking would be more successful, but this would necessitate the control of cavern passages (Fig. 22).