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Zoologisch-Botanische Datenbank/Zoological-Botanical Database

Digitale Literatur/Digital Literature

Zeitschrift/Journal: Jahrbuch der Geologischen Bundesanstalt

Jahr/Year: 2000

Band/Volume: 142

Autor(en)/Author(s): Boroviczeny [Boroviczény] Franz, Schubert Gerhard, Jocha- Edelenyi Emöke, Zsambok Istvan, Malik Peter

Artikel/Article: Hydrogeological Map 521-533 ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at

Introduction — Mineral and thermal waters: These are marked in the map as dots. Besides, there are also symbols to show pro- The legend and the mode of construction of the DAN- tection areas of drinking water and medicinal water REG hydrogeological map have been agreed at the meet- sources. ings of Austrian, Hungarian and Slovak hydrogeologists. —Tectonical parameters: Such are the lines indicating They comply for the most part with the UNESCO/IAH hydrogeologically significant faults, thrust planes and Convention of 1970 and with the methods of hydrogeo- intense tectonic disruptions, which are important in terms logical map construction (UNESCO et al. 1970, of groundwater source acquisition. STRUCKMEIER &MARGAT 1995). Out of the wells used for water supply, due to the very great number, only those have been indicated which are of Hydrogeological regional units major importance. However, nearly all thermal wells have been shown. Almost all wells used to monitor confined Practically all kinds of aquifers according to the type of water and karst water have been shown because their fre- permeability are present in the map. There are fissured quency carries relevant information on the accuracy of the crystalline hard rocks, karstified Mesozoic aquifers and map. Of the groundwater monitoring wells, each well with porous aquifers of different stratigraphy and permeability a long detection period is shown. The water bases for each value. We distinguish them first of all according to perme- water works in operation as well as each area considered ability type and then according to stratigraphy. as a potential for a prospective water supply opportunity are also indicated. Aquitards and fissured aquifers The hydrogeological setting of the area, shown on the DANREG hydrogeological map, is largely predetermined No rock can be considered to be absolutely imperme- by the hydrogeological features of the Neogene and able. Considering the fact that the majority of aquicludes Quaternary sedimentary complexes, which underlie most have some fissure-type permeability, we discuss both of the region. The following features are shown on the aquitards and fissured aquifers in one chapter. They differ DANREG hydrogeological map at a scale 1:200 000: in stratigraphy, but the main features are the same: inten- — type, or permeability of aquifers — by colours/7 tints, sive heterogeneity, fissure aperture closing downwards — lithology of aquifers — shown by type and orientation with resulting decrease of permeability, and improved of hachure/21 types. hydraulic conductivity due to tectonic effects. The most important of all hydrogeological parameters Crystalline rocks (crystalline schist, gneiss) in the shown in the map are the permeability and the lithology of Sopron Hills, Ruster Höhenzug, Leithagebirge, Hain- aquifers. It should be noted that the primary objective is burger Berge, and Malé Karpaty Mts are featured by a poor to characterize aquifers, that is, to show the hydrogeolo- permeability. They contain gap water and fissure water gical quality of the most permeable complex when a only. Even the drainage effects of the mines in the Malé lithostratigraphic unit includes alternating rock types of Karpaty Mts, particularly in the area of Pernek and different hydrogeological qualities. These are divided, on Pezinok do not produce more concentrated groundwater the basis of their relative permeability, type of permeabil- outflows. ity (pore–fissure–karstic) and extent, into seven cate- The Carpathian Keuper sequences of the Mesozoic gories, each shown as a different basic colour. There are units represent an aquiclude for the karstic waters ascend- three degrees of pore permeability, or areal extent, respec- ing from the complex. The same can be stated about the tively, two degrees of fissure permeability and two Paleogene sequences consisting of sandstones and clays. degrees allowing to classify the aquicludes in stratigraph- The Lower Cretaceous rocks in the N–NW part of the ic terms (Tertiary and younger, or Mesozoic and older, Gerecse Mountains consist of two groups of rocks with respectively): different hydrogeological features, found on or under the — Hydrography, springs and karstic features: The surface. The beds of the Lábatlan Formation, consisting drainage network, springs, or karstic features, respectively, dominantly of sandstone are featured by medium imper- are shown as lines or dots. The springs are classified after meability, while the dominantly clayey Bersek Marl is their yield, and in cases of thermal, or mineral springs, impermeable [GYALOG (ed.) 1996]. their increased temperature, or mineralization, are shown, A coal-bearing sequence containing impermeable as the case may be. claymarl and clay beds is found at the base of an Eocene — Groundwater dynamics: Line markings are used to sequence of the Tertiary basins (Tatabánya, Dorog, Nagy- express the groundwater dynamics. Arrows show the flow egyháza, Mány and Zsámbék basins). Its hanging wall in- directions, dotted lines are used for groundwater divides. cludes the “suspended karst water aquifer” Szõc Lime- — Hydrogeologically important man-made objects: These stone, of excellent permeability. These beds outcrop at are mostly the hydrogeological wells. Shown in the map the marginal areas of the mountains, forming an infiltra- are those wells, which have yielded any hydrogeological tion area. At some parts of the area, they have a direct information, or served as potable water sources, or to mon- connection with the “main karst water aquifer”, due to itor long run variations of the water levels and the dis- structural setting. In the basement of the Tatabánya Basin charge from surface streams. —in accordance with the central zone of the syncline

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structure — there are Triassic, Jurassic, and Lower and The Oligocene–Miocene, Miocene, dominantly sand Middle Cretaceous rocks. Out of the latter, the Környe and unconsolidated sandstone underlying rocks of the an- Limestone which is also a “suspended karst water desite sequence (Garáb Schlier and Budafok formations) aquifer” is of hydrogeological importance. In the base- of the Börzsöny Mountains are medium, here and there ment of the Dorog Basin, Triassic, Jurassic and Lower good, at other sites poor aquifers. They come to surface at Cretaceous rocks are found, whereas the basement of the the S–SE margin of this orographic unit. In the southern Nagyegyháza, Mány and Zsámbék basins is made up by and western parts of these mountains, close to the surface, Triassic carbonates. the foraminiferal clay-marl and clay beds of the imperme- In the Gerecse Mountains, the beds of the Oligocene able Szilágy Clay Marl Formation overlies the volcanic Csatka Formation, featured by medium permeability and sequence. It is from here that the beds of the Badenian by rather varied lithology, clay, clay-marl as well as sand, Leithakalk (Rákos Limestone Formation) are known. sandstone with a varying grain size are of considerable These are of good permeability but appear in a small thick- extent. Due to a pre-Oligocene denudation, these beds ness and not contiguously; therefore they are of subordi- often directly overlie the “main karst water aquifer nate importance for hydrogeology. sequence” consisting of Upper Triassic rocks. At the SE The Neogene volcanic complex crops out in the eastern part of the mountains, the biogenic calcareous sandstone part of the area under study. In the east the sediments of the and sandstone beds excellent permeability, belonging to Ipeﬂská pahorkatina Highland fringe the volcanoclastics the Sarmatian Tinnye Formation are typical, also outcrop- of the Krupinská planina Plateau, Börzsöny Mts and the ping in a large area in the Zsámbék Basin. Dunazug Mts (KASZAP 1976). The volcanic complex has a In the Pilis Mts and Buda Hills, Oligocene rocks of complicated groundwater circuit. It is possible to delineate varied lithological features are present. The Mány within the area of Neogene volcanics a shallow subsurface Formation consists of sand, clay and gravel. The Hárshegy groundwater circuit bound to the cover units as well as to Sandstone that comprises also subordinate argillaceous the zone of increased jointing, in which the regimen is dis- and coal-bearing beds, and the Buda Marl (marl and clay- tinctly influenced by the climatic conditions. A part of marl) have a considerable areal extent. The latter two groundwaters circulates down to 100–200 m, or even reduce the karst type infiltration in the surrounding area. deeper, where the discharge regime of the structure reach- Along the Danube, the impermeable beds of the Kiscelli es an equilibrium. The results of extensive drilling in the Clay are of importance in which sulphatic groundwaters area of the Krupinská planina Plateau show that the have been produced due to decomposition of the pyrite groundwater sources with the greatest yields occur where content of the clay. The Cserhát Hills are also built up by the tectonic unrest played an important role, i.e. in the Oligocene (TÓTH &VERMES 1984). East of the area of lower sections of streams. If the permeability of a rock extent of the Garáb Schlier which is typical at the margin body is enhanced by tectonism, the yields from wells at a of the Börzsöny Mountains, and of the Budafok number of places reach 20 to 30 l/sec. The permeability of Formation, the Mány Formation featured by a varying the volcanic rocks show some zoning. Due to weathering lithology (sand, clay and gravel) and a medium imperme- and to the filling of pores with weathering products the ability is found on the surface, or in subsurface position. In permeability of the upper part of volcanic complex, down NE, in a larger area, it grades into sand and sandstone. The to a depth of 30–50 m, is lower. As a result, most wells impermeable Lower Oligocene Kiscelli Clay occurs in the have the yields below 5.0 l/sec. The Neogene volcanic eastern part of the map sheet. region is poor in springs. Small strata-bund springs occur The silica-cemented Hárshegy Sandstone of the within the eroded blocks. There is a number of small scree Cserhát and of the blocks on the left bank of the Danube is exsurgences, which dry-up during the dry season. Their heavily tectonized. Consequently it does not impede the discharge only rarely exceeds 0.2–0.3 l/sec. infiltration towards underlying strata. Towards the Pest Plain in S direction, the hydrogeo- Karstic aquifers logical setting becomes more varied. The Fót Formation consisting of sandstone and calcareous sandstone has a The karst water stored in the Triassic —in Austria and considerable extent and rocks that appear on the surface on Slovakia Middle Triassic, while in Hungary mainly Late the right bank of the Danube also appear at a lower terrain Triassic— are of major importance from the viewpoint of position. In continuation of the Dunazug Mountains sever- drinking water supply due to extreme permeability and al occurrences of the Miocene Tar Dacite Tuff Formation water storage capacity of those aqifers. are known, and S of it there are impermeable clay and The carbonate rocks having a thickness of several hun- clay-marl beds of the Miocene Baden Clay. At the south- dred metres as proved, but of several thousand metres as ern margin of the map sheet, the calcareous sandstone beds estimated, represent a drinking water base of outstanding of the Sarmatian Kozárd Formation are known, whereas in importance for Hungary. The original natural state has the SE corner, the Pannonian Basin marginal rocks of been strongly altered during the past decades due to a min- Great Hungarian Plain) appear. These comprise the imper- ing water withdrawal at a rate of 300 m3/min performed in meable clay-marl and lignite beds of the Late Pannonian the Eocene coal basins. The karst water level and the Tihany Formation and the lacustrine clay and sand beds of piezometric pressure level decreased by 30 m on the aver- the Zagyva Formation. age in the mountains, and by nearly 100 m in the mining

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areas. This caused, particularly along the major tectonic lukewarm and warm springs resulting from fault lines and lines the major springs (Tata, Dunaalmás) uprushing along supplied with water dominantly from the deep karst. Their faults found at the hill margins to run dry, as well as the water output was negatively affected by water intake water output of thermal springs of thermal karsts in activities at Tatabánya, Mány and Dorog, through a com- Budapest to decrease. In the early 90's, the mining activi- mon watershed formed in the Buda and Pilis Mts. ty was considerably reduced, and the restoration of the The occurrences of freshwater limestone originating karst water system began. For the time being, there are from spring activities in the region of Budapest, and the only two brown coal mines —the Mány mine and the Holocene alluvial deposits of the Danube forming a bank- Lencsehegy mine near Dorog— where water withdrawal filtered water base are of more than local importance from for mining safety purposes is performed, at a total rate of the hydrogeological point of view. 36 m3/min. Some water withdrawal pits established for In the Mesozoic basement of the Dunazug Mountains, mining purposes at Tatabánya and partly in Dorog were outcropping in a very small area at Esztergom only, Upper furnished with a regional drinking water supply network Triassic carbonate rocks are included. The recharge of even during the period of coal mining, the replacement of karst springs at Esztergom is provided from the water which with local water bases is a current task. catchment area in the Pilis Mts, along tectonic lines. From the regional point of view, we can find karstified The blocks outcropping on the left side of the Danube, carbonates in the NE part of the Transdanubian Range, featured by a small areal extent, are built up from Upper where the elevated blocks of the Gerecse, Buda and Pilis Triassic limestone and dolomite, and of the Eocene lime- Mts belong to the southern wing of the syncline. They are stone. A hydrological link is probable between the built up mainly of Mesozoic carbonates and form karst blocks. In their cover the silica-cemented Hárshegy Sand- type infiltration areas, including the Tertiary basins locat- stone is included but its thickness is not considerable and ed between them (SIPOSS 1988). it is heavily broken, therefore, it does not impede the in- The Gerecse Mts is divided into three parts with regard filtration. There are no springs near the basement blocks, to hydrogeology. The southern part of the mountains is and the infiltrating precipitation flows towards SE into built up by Upper Triassic, heavily crumbled Haupt- the depth towards the Nagyalföld (Great Hungarian dolomit of excellent water storage capacity. Its hydrogeo- Plain). logical behaviour is often similar to that of a porous rock, In the Slovak part of the region, most important are the being intensive fissured. The Upper Triassic Dachstein- karst waters of the Middle and Upper Triassic carbonate kalk constituting the bulk of the middle part is outcropping aquifers in the Malé Karpáty Mts. Some springs and karst or subcropping. This rock is of excellent permeability con- development are bound also to Lower Jurassic limestones. trolled by its karst type passage and cavity systems. In the vicinity of Bratislava, in the areas of Propadlé These here and there form considerable caves primarily (Jurassic — envelope), NE of Borinka and Píla there are linked with tectonic lines (JOCHA-EDELÉNYI &GONDÁR- small segments of these rocks, which drain the surface and SÕREGI 1996). Over it —towards NW on the surface, in the underground waters from the neighbouring complexes. accordance with the general direction of striking, and in The Mesozoic rocks, situated in tectonic position below the separate Tata block— Jurassic carbonate rocks are the overthrusted crystalline rocks, account for the forma- known. They partly show a behaviour similar to that of tion of karstic springs of several tens of litres per second Dachsteinkalk, and they partly have a poorer water storage discharge. A narrow strip of limestone and cherty lime- capacity as compared to Dachstein Limestone, due to their stone, stretching from Èastá to Horné Oreany, is being argillaceous beds. The occurrences of freshwater lime- dewatered by springs with a total yield of 32–94 l/sec. stone in a considerable extent and thickness at the N and The most important concentration of the karstic waters NW parts of the Gerecse Mts originate from an important in this mountain range is bound to the Middle to Upper Quaternary hydrogeological event taking place in the area, Triassic limestone-dolomitic sequences of the KríΩna and namely a long-term spring activity. This has lasted even to Choè Units. Between Kuchyòa and Loonec the KríΩna date, being related to the uplift of the mountains (JOCHÁNÉ Unit carbonates form a SW–NE striking strip, which dips EEDELÉNYI &CSEPREGI 1994). steeply north-westwards to reach a considerable depth. The Buda Hills and the Pilis Mts consist dominantly of They are underlain by the hydrogeologically unfavourable dolomite and limestone beds. In the Buda Hills, in addi- sequences of the envelope unit, mainly by marly slates and tion to the carbonate rocks of the Dachsteinkalk and the limy sandstones of Albian and Cenomanian age. Un- hauptdolomit Formations, also the several hundred m favourable Carpathian Keuper sequences of the unit prop- thick beds of the Middle Triassic Budaörs Dolomite play a er represent an aquiclude for the karstic waters ascending considerable role in the “main karst water aquifer from the complex. Such hydrogeological setting does not sequence”. At the S–SW parts of both mountains, the well allow to assume a passage of karstic waters from the karstified, excellent aquifers belonging to the Upper KríΩna Unit into the underlier of Tertiary sediments of the Eocene limestone and featured by an abundance in caves Záhorská níΩina Lowland. This carbonate complex occu- of thermal spring origin (Pál-völgy, Szemlõ-hegy, Ferenc- pies an area of some 20.6 km2 and its dewatering, mainly hegy) [SCHMIDT (ed.) 1963] are known in a considerable into the Morava River, and partly into the Váh River thickness. The hydraulically uniform karst water aquifer drainage systems, takes place via springs and surface formed in karst rocks are tapped along the Danube by streams. A total discharge from this structure via springs is

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153 l/sec and 48–70 l/sec pass via concealed discharge depth of 4 to 8 m using 11 dug wells located between the into the surface streams. villages Nagyigmánd and Kocs, in the valley of Csicsói-ér In the Austrian part of the DANREG area an important (Csicsó brooklet). This medicinal water is due to a special karstic aquifer is the Badenian and Sarmatian Leithakalk, hydrogeological situation, namely, that the magnesium too, which occurs around the Leithagebirge. This content of Triassic dolomite clasts originating from the Leithakalk makes up with the accompanying Badenian Vértes is leached by the sulphatic groundwater due to and Sarmatian sands a single hydrogeological unit. The decomposition of the pyrite in the Pannonian grey clay. In recharge can be explained mostly by infiltration of brook- its original state the water has a magnesium sulphate con- lets, which come from the crystalline core of the tent of 42 to 70 g/l which is, however, suitable for medic- Leithagebirge and ooze away as soon as they reach the inal purposes only when diluted [SCHULHOF (ed.) 1957]. Leithakalk. This karstic aquifer provides for example the The karst water stored in the Upper Triassic rocks — radial well of Purbach which is able to produce 50 l/sec. featured by cracks and fissures— in the Transdanubian Range came to the surface through a number of famous Mineral and medicinal waters spring groups during the period preceding the large-scale water withdrawal. Several wells were used to expose ther- At the northwest foot of the Hainburger Berge mal water with Ca-Mg hydrogen carbonate content from (Austria) which represent the southernmost branch of the beds at a depth of several hundred metres, and —in some Malé Karpaty Mts there is the thermal water occurence of places at a depth of one— two thousand metres. Bad Deutsch Altenburg. It is connected with Triassic car- At Ács, an outlet water flowing out at a rate of 1700 bonates, within which the thermal water ascends from the l/min at a temperature of 70 °C and having a dissolved bottom of the Vienna Basin (WESSELY 1983). The whole matter content of 1120 mg/l was obtained from a dolomite discharge of the thermal water is several tens of l/sec filtered by Miocene limestone beds [BÉLTEKY (ed.) 1965]. (GANGL 1990, p. 3.). The content of dissolved matter At Komárom, an outlet water was obtained from

amounts to approximately 3200 mg/l, the content of H2S Triassic rocks filtered by Miocene and Oligocene beds, to 15 mg/l (ZÖTL &GOLDBRUNNER 1993, p. 272.). flowing out at a rate of 2500 and 550 l/min, at a tempera- In the same way the thermal springs of Mannersdorf at ture of 60 °C and 40 °C, respectively. the north-western foot of the Leithagebirge are connected At a part of Tata, named Tóváros, the karst water that with the occurrence of Triassic carbonates. The dissolved infiltrated in the outcrop areas found in the Vértes and substances amount to approximately 1500 mg/l Gerecse Mts before the period of karst water level reduc- (ZÖTL &GOLDBRUNNER 1993, p. 268.). tion, was flowing along major fault lines and broke to the In Edelstal —this village is situated in the south of the surface in springs forming ponds. The 160 springs supply- Hainburger Berge— there is the mineral water deposit of ing the 17 smaller or larger ponds had a total water output Römerquelle. The aquifer of this mineral water is Triassic of 130 000 l/min, at a temperature of 20 to 21 °C. dolomite and Pannonian sand. The content of dissolved The springs in Esztergom, in the area between Kis- matter runs around 1000 mg/l (ZÖTL &GOLDBRUNNER Duna-ág and Várhegy (Castle Hill) uprush within a circle 1993, p. 279.). with a radius of some 150 metres, are bound to major tec- The Balf medicinal waters that have been famous for tonic lines. They were used during the centuries for vari- centuries for the curative effect of drinking and bathing ous purposes (to make horses or ducks swimming, Turkish cures, break to the surface from groundwater springs bath, swimming-pool, slaughterhouse, then various forms welling forth at the SW corner of Lake Neusiedl/Fertõ). of bathing). The water had a temperature of about 28 °C. The six springs of low water output (6 to 22 l/min) are The yield of these springs, an average of 200 l/min was partly seasonal, giving sulphurous water. It is disputed linked with the water level of the Danube and eventually whether the hydrogen sulphide is of postvolcanic or palu- increased even to a tenfold value during a flood. A well dal origin, whereas carbon dioxide is clearly supposed to drilled in the beginning of the 20th century produced water be postmagmatic. The sulphurous water springs include flowing out at a temperature of 27 °C from Dachsteinkalk, the springs called Mária-, Fekete- and Wolfgang-forrás, with an initial yield of 3300 l/min [ˇKVARKA 1989]. whereas the springs named Savanyúvíz I. and II. and In the Lepence Valley (Visegrád), a water flowing out István are hydrogen carbonatic. In the 70's, a couple of at a temperature of 38 °C, with an output of 480 l/min., wells were drilled in order to check and control water was obtained from the andesite and from the tectonic zone withdrawal. in the cracked-fissured Dachstein Limestone underlying In Hegykõ village, a well with a depth of 1500 mm the Oligocene beds and the andesite. The water has a Ca- taps Tortonian clay-marl/sandy marl and Palaeozoic Mg hydrogen carbonate content, and a total dissolved sericite-muscovite schist and calcareous phyllite, supply- solids (TDS) content of 1627 mg/l. ing a medicinal water with a high —8 g/l— salinity and At Leányfalu, a water flowing out at a temperature of characteristic sodium hydrogen carbonate content, a tem- 45 °C, with an output of 560 l/min and a total dissolved perature of 57 °C and a considerable fluoride content matter content of 1161 mg/l was obtained from Triassic [BÉLTEKY (ed.) 1965]. limestone. In the Papsziget borehole (Szentendre), water The Igmánd medicinal water is a bitter water with flowing out at a temperature of 35 °C, with Ca-Mg hydro- magnesium sulphate which has been produced from a gen carbonate and a total dissolved matter content of 1472

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mg/l was obtained from Eocene limestone and Triassic The aquifer supplying Széchenyi Spa with hydrogen dolomite, with an output of 60 l/min only. carbonatic water is a Dachsteinkalk found at a depth of At Ráckeve, on the left side of the Danube, a water flow- nearly 1000 m. The water has a temperature of 76 °C and ing out at a temperature of 61 °C, with an output of 10001 an output of 3200 l/min. l/min and a total dissolved matter content of 812 mg/l was The Pascal Spa in the Zugló district of Budapest is obtained from Pannonian sand at a depth of nearly 1000 m. supplied with a hydrogen carbonatic water of a tempera- The Budapest springs supplied a daily amount of 40 ture of 70 °C at a rate of 900 l/min, from a Dachsteinkalk million litres of warm and 30 million litres of lukewarm hit at a depth of 1400 m. water before the period of an intervention into water cir- Since the southern boundary of the map sheet crosses culation, along the zone where the areas of the Trans- Budapest, several famous thermal water occurrences (such danubian Range which bumped into the depth and the as the Rudas and the Gellért Spa and bitter water occur- Great Hungarian Plain encountered, through springs flow- rences known in the SW part of Budapest are located out- ing out at the boundary between permeable and imperme- side it. able beds. At the northernmost part of the Buda side, the Eocene Porous aquifers and Triassic rocks in a Pünkösdfürdõ borehole supplied water at a temperature of 24 to 25 °C, with an output of Due to extensive sedimentation in the subsiding 2000 l/min. At Csillaghegy, lukewarm water at a tempera- Tertiary and partly Quaternary basins, many clastic ture of 19 to 22 °C is known, and the spring yielded deposits were generated, comprising also less permeable 2000 l/min. or even impermeable fine-grained sediments. Their verti- The boreholes drilled to a depth of several hundred cal or lateral extent is varying fastly. Thus providing only metres provided an output of 150 to 100 l/min. The springs limited possibilities for concentrated groundwater flow. at Roman Bath break to the surface from the alluvial muddy But still there is a huge enough mass of coarse-grained sand beds of the Danube. The Romans used it as drinking sediments serving as an important groundwater source water. It had a temperature of about 22 °C and at the site it both in Quaternary and Tertiary units, of confined water broke to the surface calcareous tufa cones were found. type, unconfined type and bank-filtered type. During the 19th century, the springs had a total output of 7388 l/min. At present, as shown by measurements, it varies Porous aquifers in Tertiary sedimentary basins between 2500 and 7100 l/min and is considerably influenced by the water level of the Danube. Most of the region is underlain by a Neogene sedi- The springs and dug wells belonging to Császár Spa mentary complex. In the east of the Alpine–Carpathian arc also took water from the alluvial sand beds of the Danube. there is the Pannonian Basin, within the Alpine–Carpath- The drilled wells penetrated into the Buda Marl. The water ian arc lies the Vienna Basin. Both are filled with Neogene of 55 to 62 °C temperature has chloride, sulphate and sediments. These basins were formed, as a result of intense hydrogen carbonate content. The springs of Lukács Spa tectonic downslip faulting, along their inner side. Their have a temperature range from 27 °C to 64 °C. The sites filling has in its deepest parts a thickness of several thou- where they break to the surface are in partly calcite-filled sand metres. fissures of the Buda Marl. The chemical composition is These Neogene sedimentary complexes are composed similar to that of the Császár Spa water, but the contents of mostly of unconsolidated strata of gravels, sands and sulphate and chloride are at some sites are slightly higher. clays. These are locally cemented by the calcium carbon- In order to compensate for a decrease in the yield of natu- ate to form conglomerates, calcareous sandstones or ral springs, a couple of boreholes supplying water at an organogenic limestones. The Neogene sediments lie pre- output of 500 to 3500 l/min were drilled in both baths. dominantly horizontally, or dip at an angle of up to 10°. Boreholes on Margaret Island were drilled in order to Their thickness in both the Vienna and the Pannonian capture “runaway” springs found in the Danube. The bore- basins, increases towards the basin centres. The maximum holes drilled into the Buda Marl and the Eocene limestone thickness of the Neogene cover in these basins reaches had a maximum output of 10 500 l/min and a temperature even 5500 m. Both areas were subject to several marine varying between 43 °C and 68 °C. The water has a chlo- transgressions and regressions. ride, sulphate and hydrogen carbonate content. Recently, Alternation of non-permeable clays with permeable the water obtained from a borehole drilled into Triassic sands and gravels and their basin configuration causes rocks is being bottled for sale. groundwater levels to become confined and to acquire A borehole drilled at Tungsram Spa in Újpest has sup- either a positive, or a negative piezometric level. The plied water at a temperature of 24 °C, at a rate of 37 l/min, blocky structure of the basin filling, the granulometric from Eocene limestone. composition of sediments and their thickness and deposi- The wells supplying with water the Dagály Spa and a tional setting influence, in addition to other factors, the bath named Elektromos obtain it from a depth of 125 m circuit and the recharge of groundwater in the permeable and 250 m, respectively, from an Eocene limestone bed, at Neogene sediments. a temperature of 41 °C and 46 °C and at a rate of 6200 and Individual artesian horizons have only rarely a yield of 86 l/min, respectively. 10 l/sec, in most cases only 1–3 l/sec from one well.

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Several concomitantly pumped horizons may produce a On the basis of its tectonic setting the eastern margin- yield of up to several tens of l/sec. al part of the Vienna Basin on the Slovak territory has been divided into several units: The marginal blocky region of the Malé Karpaty Mts, VIENNA BASIN composed of slightly waterlocked Badenian sediments, In Austria the following geographic sectors of the overlain by Quaternary sediments (proluvial, fluvial and Vienna Basin are comprised by the DANREG region: deluvial sediments) of small thickness. We presume that North of the Danube there is the Marchfeld; south of the within the marginal blocks area of the Malé Karpaty Mts Danube there are the Rauchenwarther Platte, the there is a hydrogeological continuity between the Lower Arbesthaler Hügelland, and adjacent to them the north- Badenian gravels and the marginal Mesozoic deposits. eastern end of the Mitterndorfer Senke. The Upper Badenian, represented by clay, sand and sand- The Marchfeld and the Mitterndorfer Senke are cov- stone, is hydrogeologically insignificant. ered by mighty Quarternary sediments. By way of contrast Situated between Marchegg and Plaveck˝ Mikulá, the in the Rauchenwarther Platte and the Arbesthaler Zohor Depression is a distinctly sunken, 7–8 km wide and Hügelland —both lie about 50 m above the Marchfeld and some 36 km long graben, limited by faults. Two highs (the the Mitterndorfer Senke— the Pannonian underground is RohoΩník and the Lozorno ones) divide it into three par- screened by a more fragmentary Quarternary cover of tial depressions (Solonica, Pernek and Zohor–Marchegg gravels and loess. The Lower Pannonian is mainly build depressions). The depression is filled by Quaternary sedi- up by sandy-clayey sediments, the Upper Pannonian ments, which are of great hydrogeological interest. They includes mostly clay-marl. Therefore these Tertiary sedi- are underlain by Dacian sediments. Several aquifers locat- ments can be used for local water supply only. ed in Dacian sediments (sands and gravels enclosed in On the eastern margin of the Vienna Basin, on the clays) have been intersected in the Zohor depression by slopes of the Leithagebirge and the Hainburger Berge as deep hydrogeological wells. This groundwater is charac- well as in the Brucker Pforte which is situated in between, terised by artesian overpressure. not only Pannonian but also Sarmatian and Badenian sedi- In the Plavecká depression Sarmatian and Pannonian ments crop out. These consist mainly of gravel, conglom- sediments underlie Quatenary deposits. West of the line erate, Leithakalk, sand, sandstone and marl, respectively connecting Plaveck˝ Mikulá with Plaveck˝ Peter the clay marl. They are —above all the Leithakalk— of great Quaternary in the Plavecká depression is underlain by importance for the water recourses management in this Sarmatian and Pannonian sediments. Since the clayey region (compare chapter “Karstic aquifers”). sequences outnumber the beds of sands, sandstones and The Mattersburger Becken (also called Eisenstädter gravels, these sediments are of little hydrogeological inter- Becken or Wulkabecken) which is bounded by the est. The Lakár High is a Neogene horst. Also the Leithagebirge, the Ruster Höhenzug, and the Soproni- Láb–Malacky Horst consists of Pannonian and Pontian hegység (Sopron Hills) is also a part of the Vienna Basin. sediments. In the central region of the Mattersburger Becken The Kúty (Suchohrad–Gajary) depression is filled by Pannonian sediments from below a gappy Quarternary Dacian sediments (clays with abundant sand beds), over- overburden. The Pannonian is underlain by Karpatian, lain by Quaternary sediments. The following Lakár High Badenian and Sarmatian formations, which crop out in the is made up by Neogene (Karpatian) formations, overlain marginal regions of the basin. These include gravel, con- by thin Quaternary sediments. Less widespread are con- glomerate, sand, sandstone, Leithakalk, and marl, forming glomerates and sandstones with calcareous clay intercala- a permeable complex, whereas the very low permeability tions. The conglomerates and sandstones are fissure Pannonian sediments (mainly sandy clay) form an upper aquifers. The central part of the high is made up predomi- confining bed. nantly by calcareous clays. The hydrogeological wells As generally known the pre-Neogene basement of the drilled in this area were negative. The younger Neogene Vienna Basin is strongly structured (KRÖLL et al. 1993). In sediments (Upper Badenian and Sarmatian), which occur Austria the deepest part is situated east of Vienna; there in the western part of the high, are of no hydrogeological the Schwechat depression reaches more then 5200 m interest. The artesian wells have produced small yields beneath sea level. Further structures within the project (0.01–0.45 l/sec). area are the Gr. Engersdorf, the Marchfeld, the Lassee, and The Láb–Malacky Horst is an area of limited hydro- the Mitterndorf depression as well as the geological interest. The Pontian rocks are represented by Aderklaa–Matzen, the Zwerndorf–Vysoká, and the clays with fine-grained sand intercalations and lignite Enzersdorf Highs. From oil exploration it is well known seams (the Èáry Formation). It is general in this tectonic that in the central region of the Vienna Basin the mighty unit that the Neogene represents an impermeable footwall Tertiary sediments contains mainly stagnant saline of the Quaternary fluvial and eolian sediments. groundwater (WESSELY 1983). Only at the margins can be The Neogene rocks of the Suchohrad–Gajary depres- expected a deeper circulation of less saline groundwaters. sion are Dacian and Pontian sediments. They are overlain As recharge area one can presume mainly Triassic carbon- by Quaternary sediments. Outcropping are variegated ates but also Leitha limestones, Miocene gravels and sands clays, locally with gravels and sands (Gbely Formation) which crop out at the margin of the basin. and limy clays with sand and lignite intercalations (Èáry

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Formation). The clayey character of the formation, with formations. However, the aquiferous complexes are, in sand beds, was favourable for the formation of artesian general, only moderately watered and the groundwaters water horizons with, however, predominantly negative are bound to relatively smaller, for the most part, up to 10 water level. Their number influences the yield of wells, m thick sand beds. These are too indistinctive to allow for which ranges from 0.2–2.0 to 5–10 l/sec. their monitoring from a greater distance. In the Petroleum and natural gas, bound to the Upper Subcarpathian region the Quaternary is underlain by Sarmatian horizons of the Vienna Basin, spoil the ground- Pannonian sediments. In the central depression there are water quality in this formation already at depths of outcrops of Dacian and Rumanian sediments, which con- 100–120 m. The yield of artesian horizons, tapped by a stitute, together with the Quaternary ones, a single aquifer well, is some 6 l/sec, but locally even more. The best with free surface. In its deepest part— in the Gabèíkovo aquifers occur in the Upper Pannonian beds, composed of depresion (Gabèíkovo, Baka) the thickness of Dacian and sand and locally of fine gravel. Rumanian sediments attains 520–600 m. A complicated geological-tectonic setting of the broader surroundings of Komárno (southern parts of Nitra and PANNONIAN BASIN ≥itava drainage systems and of the Váh–Danube conflu- With regard to the tectonic setting the Austrian part of ence) has its bearing on a complicated hydrogeological the Pannonian Basin can be divided into the Neusiedler setting of this area. Tectonically shaped, lower, or higher Bucht and the Landseer Bucht. The Neusiedler Bucht highs of Neogene rocks alternate with troughs filled with which includes the Heideboden, the Parndorfer Platte, and Quaternary or Rumanian sediments, respectively. the Seewinkel is mainly filled with mighty Pannonian Northwards, the area centred around Kolárovo forms the sediment. Their thickness increases toward the east. The extensive Kolárovo depression (100–120 m) filled with deepest part of the Neusiedler Bucht reaches 3600 m Rumanian, Dacian and Pontian sediments. These are beneath sea level (KRÖLL et al. 1993). The Parndorfer sands, locally with fine gravel and with plenty of calcare- Platte —to the north it is limited by the Leitha Valley— ous-sandy concretions. The Kolárovo beds are underlain lies about 50 m above the surrounding plains. Its Tertiary by Upper Pannonian sediments. A characteristic feature of substratum is covered by older Pleistocene gravel. the area east of Komárno (Kravany–Chﬂaba) is that the Contrary to this the Tertiary of the Heideboden and the Quaternary sediments east of the Kravany fault are under- Seewinkel is mainly overlain by younger Pleistocene lain by Neogene volcanics and Paleogene rocks. gravels. Within the Tertiary sediments of the Neusiedler In the Fertõmellék Hilly Land there are good aquifers: Bucht the groundwater flow velocity is in general very the Sarmatian gravel and sand strata the water of which is slow. In the area of Neusiedl and Gols numerous artesian utilised by the wells at Csalánkert and Tómalom whereas wells should be mentioned (TOLLMANN 1985, p. 545). the Badenian and Sarmatian limestone beds are utilised by In the Landseer Bucht (Oberpullendorfer Becken) the Fertõrákos Water Works. The Badenian Clay occur mostly Pannonian sediments, overlain by a Formation is impermeable. The Lower Miocene Quaternary overburden, mainly loess. These Pannonian “Ligeterdõ” and “Brennberg” gravels are not important sediments consist chiefly of sands and make up an utiliz- from the hydrogeological point of view due to their minor able aquifer. water recharge and small areal extent. In regard to hydro- On the southern slope of the Sopron Hills crop out also geology, the Lower Pannonian rocks are less important gravels, Sarmatian marl, and Badenian sediments which than the Sarmatian ones, but both sequences are featured are composed of Leithakalk, sand, and marl. In by a positive pressure. In regard to water exploitation, the Deutschkreuz the mineral water “Juvina“ is being pro- confined waters of the Upper Pannonian that can be found duced from such Badenian sands. Its water temperature is at a greater depth are of greater importance. The sandy about 15 °C. This shows that this mineral water is ascen- beds found in the range of 40 to 200 m have the best water dent (ZÖTL &GOLDBRUNNER 1993, p. 218.). supply capacity. The regional groundwater flow directions In the Slovak part of the Pannonian Basin, most of the are from Seewinkel towards S–SE and from the Quaternary cover is underlain by Pliocene sediments, only Sopron–Vas Plain towards N–NE, towards the Hanság the marginal parts are floored by Miocene rocks. Main Channel as the direction of groundwater erosion Lithologically, clayey sediments prevail, with moving base for the wider environment. The pressure level in the sand beds. The uppermost part of Neogene —the Dacian- Pannonian aquifer sequence drops from a value of Rumanian— is composed predominantly of sand, gravel 150–160 m above the Baltic to a value of 115 m NW of the and clay. Sopronkövesd–Pereszteg Line. Thermal water can be pro- From the hydrogeological point of view, the lowland duced from a depth of greater than 800 m, from Miocene represents an extensive, indistinctly articulated artesian or Pannonian beds overlying the Palaeozoic (Petõháza — structure. The Dacian and Rumanian combined with the 71 °C, Hegykõ — 57 °C) [BÉLTEKY (ed.) 1965]. Quaternary sediments form a common unconfined A part of the northern foreland of the Transdanubian groundwater reservoir. Owing to the deep entrenchment of Range which is shown in our map has a uniform hydroge- Miocene sediments (to a depth below 100–2000 m), the ological setting. The Bakonyalja–Vértesalja area, then fur- hydrogeological features of the natural waters are essen- ther on, the major part of the Komárom–Esztergom Plain tially determined by the Pannonian, Pontian and Dacian stretching as far as the Danube are areas of Pannonian

deposits with a great thickness, overlain by thin discharges. The recharge is mostly done by infiltration of Quaternary deposits only. Its thickness is 4000 m at the rivers which come from the highly humid Alps. Rába Line, or at the sites where it has a surface, or subsur- In the area of the Rauchenwarther Platte and face position and becomes gradually thinner towards E as Arbesthaler Hügelland the Tertiary is covered by a far as the Dunazug Mts and towards SE towards the Quaternary overburden: Pleistocene aeolian deposits and Bakony–Vértes Mts, that is, the basin margins. The Late gravel plains. As a consequence there are more local Pannonian sequence which is better in regard to water sup- groundwater bodies of lower productivity. ply capability has a thickness of 1000 m at Ács and also The Quaternary filling in the Slovak part of Vienna becomes thinner towards the margins. At Tata, it is only Basin is divided into several neotectonic basins and rela- 100 m thick. It is also built up dominantly by clay-marl. tively uplifted structures. The intercalated sand beds are of medium, or poor water The marginal, blocky area of the Malé Karpaty Mts, supply capacity. Nonetheless —for lack of a better— they composed of Quaternary sediments (proluvial, fluvial and are tapped by the major part of the wells in a depth range deluvial sediments) of small thickness and of regionally of 50 to 200 m. low degree of permeability. We have only a few data on the water supply capacity The Zohor depression, between Marchegg and of the Miocene strata. A larger amount of water can only Plaveck˝ Mikulá, is a distinctly entrenched, tectonically be produced from them at the sites where they are also limited graben. Two partial highs (the RohoΩník and recharged presumably from the underlying Mesozoic Lozorno highs) divide it into three partial depressions (the karst. Such sites are the thermal wells at Bábolna and Solonica, Pernek and Zohor–Marchegg depressions). It is Komárom. filled by Quaternary sediments, which are of great hydrogeological interest. They are underlain by Dacian sedi- Quaternary porous aquifer ments. In the Solonica reservoir the thickness of aquiferous Quaternary sediments ranges from 29.0 to 78.0 m. The The Quaternary clastics offer an excellent opportunity Quaternary sediments in the Pernek groundwater reservoir to produce water when the have sufficient thickness and attain a thickness up to 120 m. In the Zohor–Marchegg effective porosity — even at a specific flow rate of 2000 reservoir the thickness of gravels and sands varies between l/min (33 l/sec), and in some cases even 12 000 l/min 48.0 and 103.0 m. (200 l/sec). In the Plavecká Depression larger amounts of groundwater have been documented, originating solely from con- VIENNA BASIN QUATERNARY COVER cealed groundwater transfers (62.8 l/sec) from the Malé Karpaty Mts, into the lowland. The Quaternary is under- As mentioned above in Austria considerable parts of lain by Sarmatian and Pannonian sediments. the Vienna Basin are overlain by mighty Quaternary sedi- The Lakár High is a Neogene horst. The Quaternary ments. In the Marchfeld the Quaternary gravel has an aver- sediments are 8.5 to 22.0 m thick. A complex of eolian age thickness of 10 to 20 m (SCHÛGERL et al. 1984). In sands represents an independent hydrogeological structure areas of stronger synsedimentary subsidence —such as the overlying the Karpatian formations, which serve as an the Marchfeld Depression and the Lassee Depression— its impermeable floor to the eolian sands. The footwall of thickness reaches more then 50 m. In the southern part of eolian sands is situated above the local erosional base. The the Marchfeld the groundwater recharge is due mainly to water is supplied exclusively by the precipitation. infiltrating Danube water. A tract with a width of about The Quaternary terrace gravels of the Morava River four kilometres is influenced by the water level fluctua- situated on the Láb–Malacky Horst, with local eolian sand tions of Danube. Here the waterworks of Lobau is situat- cover (thickness 5–15 m), are not distinctly aquiferous. ed, which makes an important contribution to the water This due to their being located high above the erosional supply of Vienna — this waterworks is able to produce base. The Quaternary sediments of Kúty represent another 1000 l/sec. In the northern part of the Marchfeld the hydrogeologically important complex. In the hanging wall groundwater is being recharged mainly by precipitation. there are clays with the Dacian sandy intercalations, which The near-surface groundwater is used mainly by agricul- are also profusely aquiferous. Favourable hydrogeological ture, which has a high water demand to irrigate the fields. conditions have been observed in the Myjava River alluvi- Therefore the groundwater level has sunk considerably. um, between the villages Senica and ˇajdíkove Humence The Mitterndorfer Senke is the most important ground- (yields of wells 10–12 l/sec), near the Myjava–Morava water body of the Vienna Basin. Its Quaternary gravel and confluence. sand sequence reaches a thickness up to 150 m (BERGER 1989). Within the DANREG area —it includes only the DANUBE RIVER DRAINAGE SYSTEM north-eastern end of this Quaternary aquifer— its greatest thickness amounts about 30 m. In the Mitterndorfer Senke The Danubian deposits (gravels and sands — alluvium there are situated several important waterworks. in the area between Devín and Bratislava) in this area are Since toward the North-east the Quaternary aquifer of 2 to 18 m thick. They are overlain by inundation loams. the southwest-northeast oriented Mitterndorfer Senke The substratum consists of Sarmatian clay and granodior- becomes more shallow, in the North-east the groundwater ite. The direction of groundwater flows, as well as of

groundwater levels are in perpetual interplay with the The thickness of Quaternary deposits ranges from 8 to 20 water level in the river and in its deviation channel. m. The Quaternary is underlain by Neogene (Pontian– The PetrΩalka area is characterised by a smaller thick- Rumanian) sediments. The Kravany fault truncates the ness of fluvial gravels and sands (some 10–20 m), which whole structure to the east. Beyond this fault the overlie the Lower Pliocene clayey-sandy beds. The aquif- Quaternary is underlain by the Palaeozoic, or by Neogene erous gravels and sands have good permeability. The volcano-sedimentary rocks. water quality is at risk due to the extensive urban agglom- The Kolárovo Member (Pontian–Rumanian) fills the eration of PetrΩalka. depression between Kolárovo and Èalovo. There, the The features of the Èuòovo area are very favourable aquiferous Quaternary sediments directly overlie the also for the accumulation of groundwater. The permeability of aquiferous Upper Neogene sands and combined they form fluvial sediments in this area have the highest mean values a single hydrogeological structure with freatic surface. of the transmissivity coefficient T in Slovakia, with values The thickness of aquiferous sediments reaches 100–120 of filtration coefficient of up to 4.10–2 m/sec. The average m. The groundwater regime in this area is influenced by thickness of groundwater body is 100 m and the mean per- the Danube and its tributaries — Váh, Nitra and Mal˝ meability coefficient of 4.10–3 m/sec, is very high. Dunaj, as well as by a system of dewatering channels. The Podkarpatská (Subcarpathian) area on the left The Kravany-ˇtúrovo region. The older Danubian ter- hand side of Mal˝ Dunaj: the Quaternary is represented by races and the Holocene alluvial plains are composed of deluvial sediments, older Quaternary Danube terraces and Quaternary sediments. The terrace sediments are 10 to 15 recent Danube River deposits, whose thickness increases m thick. At their base there are well permeable aquiferous towards SE from 3–7 to 10–12 m. The extensive urban gravels and sands. The terrace groundwaters are recharged reconstruction and development of Bratislava precludes solely by precipitation water. At the terrace margins there the use of alluvial waters. Farther eastwards, the extraor- are springs with yields ranging from 0.2 to 5.0 l/sec. The dinary thickness (over 100 m) of well aquiferous gravels Holocene alluvial plain stretching along the Danube River and sands near Jelka provides good hydrogeological pre- is a low-lying, locally marshy plain. The thickness of sedi- conditions for groundwater accumulation. ments reaches 5–12 m, while the thickness of the aquifer- The ≥itn˝ ostrov region. The geological-tectonic struc- ous gravel and sand bed is 4–10 m. The groundwater is ture of the ≥itn˝ ostrov Island is not homogeneous. Due to directly influenced by the water level of the Danube. tectonics the thickness of Quaternary sediments increases Concerning the Austrian part of the Pannonian Basin towards the centre of the ≥itn˝ ostrov Island. The aquifer- —as mentioned above— in the Neusiedler Bucht mighty ous complex consisting of Quaternary to Rumanian grav- Quaternary gravels are widespread. The Tertiary floor of els and sands is the thickest in the area of Gabèíkovo and the Parndorfer Platte is covered by older Pleistocene Baka (520–600 m). gravels about 10 m thick. In the Heideboden and the The Gabèíkovo depression is an independent hydro- Seewinkel the Tertiary is overlain by younger Pleistocene geological region characterized by apeculiar geological gravels with an average thickness of about 20 m, which setting, amount of accumulated water and groundwater increases toward the east and reaches 50 m at the regime. The groundwater regime depends on the discharge Hungarian border. The gravels of Heidebodens and from the Danube and Little Danube and from precipita- Seewinkel make a relatively good aquifer (Gruppe wass- tion. Recent hydrogeological research into the regime of er 1996). Mainly in the Seewinkel its groundwater is this area has proved that this phenomenon is very com- intensively used by agriculture. Because in the Seewinkel plex. The pressure changes, brought about by large the groundwater recharge is predominantly done by pre- amounts of water, by height of the water column and by cipitation, it often comes to water shortage. the irregularity of the horizontal and vertical distribution The Sopron Basin, situated in the westernmost part of of variably aquiferous (because granulometrically differ- both Hungary and the Pannonian Basin, the Pleistocene ent) sediments, predetermine the regime at the surface and gravel cover of 3 m average thickness, overlying the at depth. In the Gabèíkovo depression the surface regime, Badenian clay, is the best aquifer. It is covered by a fine- with all signs of common groundwaters from Quaternary grained alluvial deposit. In the entire area named alluvia, takes effect to a depth of some 30 m. Below this Alpokalja (“foothills of the Alps”), it is there that the limit the influence of deep regime becomes evident with largest continuous groundwater stock is found which is all its dynamic features. also replenished by groundwater from side valleys. A part The aquiferous alluvium under the vaste ≥itn˝ ostrov of the Sopron–Vas Plain is formed by the alluvial fan Island represents a groundwater reservoir storing more found between the Ikva and Répce brooks, the material of than 10 billion m3. of relatively good quality water. The which was transported by the rivers from the Alps to the dynamic discharge throughout the ≥itn˝ ostrov profile is Pannonian terrain in the Pleistocene. This groundwater estimated at 8 m3/sec of water. aquifer is 5 m thick on the average, attaining even 10 m in The area of broader surrounding of Komárno/ the river valleys, along with the Holocene deposits. Any Komárom. This area is geologically and tectonically very considerable stock of water that can be exploited is only complicated, with higher, or lower highs of the Neogene found in the valleys. Complicated flow conditions prevail sequence and with depressions filled by Quaternary, or between the valleys, on the ridges, due to a variation in Rumanian sediments, respectively (Kolárovo Member). grain structure, and the groundwater — practically

blocked at the Pannonian terrain level — is stored in the The region called Hanság should be specially empha- Quaternary deposits. sized as an area which is peculiar in many aspects and has The Gyõr Basin is an asymmetrical Quaternary sedi- a low terrain level. It lies by 50 to 60 m deeper than the mentary basin with an axis that is roughly perpendicular to Alpokalja and it joins the shallow marshy Lake the Rajka–Gyõr Line. It is bordered by the Rába fault Line Neusiedl/Fertõ Basin. At this site, the groundwater practi- in SE. Geographically, it can be divided into several sub- cally flows in the gravel bed which is thin there. It is over- regions such as the Fertõ–Hanság Basin, Rábaköz, lain by alluvial sand, mud, peat and peat mud in which the Szigetköz, etc. It is a Quaternary fluvial clastic sequence water level has a subsurface position of 0 to 2 m. Its stock which attains a maximum thickness of 700 m at Szigetköz of water originating from precipitation and from the grav- being adjacent to Csallóköz. It consists of various types of el bed with the high terrain level is controlled by the chan- clastics but the enormous amount of stored water forms an nel system. As concerns water circulation, brief periods integral hydraulic system. This can be concluded from the are dominant. close connection between aquifer levels of the basin, fea- In the western wing of the Gyõr Basin, in the southern tured by varying position in space and varying lithological margin of Lake Neusiedl/Fertõ, the water supply capacity facies. The flow and pressure conditions of this enormous of the Quaternary beds is lower due to the fact that they stock of water are controlled mainly by the Danube. In the become thinner and have a finer granulometry. There, area called Szigetköz, the connection between the Danube water is taken from the Late Pannonian shallow confined and the groundwater can be studied through a water level aquifer (BOROVICZÉNY et al. 1992). period of 30 years for eight well series perpendicular to the A Quaternary deposit of greater hydrogeological sig- Danube. Further well series were made later for which a nificance in the northern foreland of the Transdanubian shorter detection period is available but they make the Range is only found in the Danube Valley and at a section analysis of the connection more complete. The Quaternary between smaller and larger bays connected with the clastics offer an excellent opportunity to produce water — Danube such as the Komárom–Almásfüzitõ one. At the at a specific flow rate of 2000 l/min, and in some cases Gyõr–Almásneszmély section, several older Pleistocene 4600 l/min— in the area of the entire basin, at various fluvial terraces, or terrace debris are found. These — depth ranges. In most cases, a well does not produce water except for those that are in a direct connection with the from a depth exceeding 100 m because quality is already river water— are of minor hydrogeological significance, accompanied by proper quantity by that depth. The region- due to their areal extent and position. The regional flow al flow of groundwater points, in the north, from the direction of groundwater points towards the River Rajka–Bratislava region towards SE, and from the south- Danube. ern area towards NE, that is, from both directions towards Along the Danube, its terrace formations of various the Hanság Main Channel and the River Répce, reaching age and terrain position are important aquifers. The allu- the Danube Valley through these depressions at the vial deposits at Szentendre Island supply a water base for Mosoni-Duna/Gyõr–Duna axis (Magyarország...1989). the northern part of Budapest.

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