Hidrológiai Közlöny 1949 (29. évfolyam)

9-10. szám - Értekezések - J. BOGÁRDI, D. Eng.: Report on the Ground Water Conditions of the Great Hungarian Plain

Kiterjedt talajvizszintészlelő 'kúthálózatunk megfigyelési eredményeinek feldolgozására ad útmutatást jelentős példákban a Nemzetközi Geodéziai és Geofizikai Unió Hidrológiai Szakosztályában előadott alábbi magyar tanulmány. Eredményeit az ötéves terv során a belvízmentesítés!, talajjavítási és öntözési tervek végrehajtásánál hasznosíthatjuk. U.D.C. 551.495.54 (439.14) Report on the Ground Water Conditions o! the Great Hungárián Plain* By J. BOGÁRDI, D. Eng. One of the peculiar geographic units of Europe.is to be found the lowland on the bottom of tbe Carpathian hasin extendine for about 100.000 sqnare km. originating in the sinking of part of the so-called „Tisia massivum". The deeply sunk parts were entirely covered by the layers of the third age tide, which were later concealed by Continental deposits and leveled ,to a plain land. This r^nort is limited to the part of the „Alföld". (Great Hungárián Plain) of present-day Hungary, a territory of around •15.000 square km. The average elevation of Hungárián ,,Alfö'd" above the sea-level (Adria) varies between 00 and 130 m. The territorv is sliglitly sloping to the south. In nlaces, as for instance between the Danube and the Tisza, sandhills and mounís of modemte heiaht are nresent. The Hungárián „Alföld" belongs in its entirity to the drainaae-area of the Danube. Besides the Danube, forming the western boundary, its most imoortant river is the Tisza. The foremost tribiítf r>ea of the Tisza are the Szamos, Bodrog, Sajó. Körös and Maros. The Danube is in generál charneterized by low stages in the fali and winter, while floods and lastin<* high stages oecur mostlv ín the spring and summer- The stage of the Tisza is as a rule loAvest. in summer. "The drainage area of the rivers are detached from eaoh other by low, natural elevations, ebaracterized bv a comparative permanencv. On longer streches upwards from the moutli, howerer. the boundaries of the drainage areas of the recipient river and tributáries are more or IPSS blnrred '"n aeeordance with the characteristios of the low-land. With the exoention of the Danube the streams of the Alföld, ineluding alsó the Tisza, have extraordinarily variable discharges in accordnnce' with extreme climates. After inelement winters with mneh preeipitation. the discharge of the rivers in the summer is in generál small. T^e climate of the Alföld is of a Continental character. Severe colds in the winter and vcry hot davs in summer are frequent. The aunual mean temperature is -1-10.1 to -(-11.4 C°. The mean temperitures of the diverse seasons are in order as follows: winter —0.9 to -1-0.8 C°, sprint +10.7 to -1-11.7 C°- summer -1-20.1 to +21.3 C° and fali +10.5 to +11.9 C°. The annual • Strudy presented to the Assooiation of Scientiíic Hydrology of the International Union of Geodesy and Geophysies on oeasskm of its Oslo Congress. (1948.) * Jelcint fis a Narji/ Mm var A'fald talajvíz viszonyairól. Irta Bogárdi János dr. (MagyarnyOívű kivonat a 310. oldaton.) sunshine-period in the average is 1952 to 2072 hours. The average preeipitation for the Alföld as a whole is about 580 mm. Taking into. account the average of many years, the most preeipitation appears to have been had in the north-eastern part of the Alföld where the annúal mean was around 700 mm. On the major part of the Alföld, the annual mean of the preeipitation varies between 500—550 mm. Dryest is the Alföld in the heart of it in tlie region of city Szolnok where the annual average preeipitation is less than 500 mm. This report concerns itself mainly with questions of the ground water levél (main water table). which is important from the agricultnral and forestry point-of view. This circumstance indicates in itself as to what is meant by ground water in our report. From this point of view Zunker expresses best the conception of ground water. He claims that the ground water is a mass of water filling the coherent pores of the soil which is under no pressure following only the law of hydrostatical pressure. Inasmuch as only such water masses are of consequence for the agriculture and forestry, wicli accumulate in the impervious layer next to the surface our observations and data are alsó limited to this part only. Being ontside of the sphere of the subject we shall refrain from the further discussion of question of the ,.ground water conception", so much debated in the literature. The ground water masses are subject to the law of gravitation the same as the surface waters. If their close position is insured by the impervious layers, they must be considered stillwaters. But the water table is not horizontal in such cases either that is the water table does not take its position along a level surface. Similar phenomena oecur on lioniogen soil of minor extent on level surfaces only. In generál, the water table possess-es a cerlain slope and therefore the ground water — similar to the surface water — streams in the direction of the slope• Therefore the ground water stages of certain places are influenced by the infiltration of the preeipitation, together with other factors and alsó side currents. The great soil friction as well as its extreme variation further' many other factors delay, however, . the fast pressure-difference equalization through streaming in consequence of which the water table very seldom becomes horizontal. In the .277