Vízügyi Közlemények, 1958 (40. évfolyam)
4. füzet - VII. Kisebb közleménye
f 15) Geophysical investigations are an important aid in water explorations. Gravity m<asurements and eleclric methods are used most frequently for this purpose in Hungary where pioneering work was done in the field of gravity measurements. An advanced form of the Eötvös gravity-meter suggested by 11. Böckh was used with good results for oil prospecting as early as 1915. Systematic measurements were tarted in 1921 covering the Western parts of the country, and the network of observing stations is nowhere in the world as dense as in Hungary. In water explosation this method is used mainly for the exploration of thermal waters. Geoclectric investigations are used today extensively in this country. These proved especially helpful in exploring groundwaters or artesian waters located at moderate depths. Experiments aiming at the extension of this method to waters in greater depths are under way. In special cases geochemical resp. biochemical methods may also be successful, however, no attempts have as yet been made at their application. Field experiments arc conducted chiefly for groundwater explorations. For the de termination of infiltrating quantities in karstic areas field experiments involving artificial rain have been carried out recently by II . Kessler. * # * Practical applications of exploration methods are described subsequently in connection with recent works. Owing to the considerable yield encountered, attempts to tap the aquifer system of the Szikla Spring in the Szálajka Valley by means of a shaft driven downward from an upper level proved unsuccessful. Л bottom gallery was therefore driven permitting gravitational dewatering. In order to provide storage and to ensure artificial supply to the protected spring a cutoff wall has been constructed (Fig. o). Test holes indicated in Fig. 5 have been drilled to explore geologic conditions of a spring. Following the exact location of the aquifer water was diverted to a collecting shaft by means of a subterranean baffle wall ( Fig. 4 to 7). In the course of explorations for the water supply of a rapidly expanding mining town geoclectric investigations (Fig. 10) were carried out over the area shown in Fig. 8 on basis of preliminary site surveys. The exact location of the aquifer thus determined was checked by borings. Data recorded during the drilling operation (Fig. 5) have been checked bydetermining the soil profile for every individual hole using the y-ray well-logging method (Fig. II). Recharge conditions are to be determined by extended pumping and by continuously recording the static water level. In connection with water works relying on ground water for their water supply two explorations are described (Figs. 12 to 14). In both cases the provision of water of proper quality presented the main problem. The gallery shown in Fig. 15 has been constructed by devi lopping one of the greatest karstic water supplies in the country. By means of the gallery sources could be tapped in sound, uniformly stratified rock and a considerably greater sale yield ensured. Particulars of the development are shown in Figs. 14 to 20. * * * Precipitation as the source о/ groundwater recharge has been investigated since the fifties of the last century. Karstic waters, however, were long thereafter considered juvenile waters and karstic water supplies believed to be practically inexhaustible. Both assumptions are known to be erroneous and such sources to yield but finite quantities. Investigations into the relation between precipitation and groundwater resp. karstic water recharge serve today as the basis for the solution of certain forecasting problems. As far as the recharge of artesian waters is concerned, no corroborated theory could as yet be developped. (Author's summary translated by /.. Szilvássy с. engr.)
