Hidrológiai Közlöny 2000 (80. évfolyam)

1. szám - Marton Lajos–Szanyi János: A talajvíztükör helyzete és a rétegvíz termelés kapcsolata Debrecen térségében

MARTON L. - SZANYI J.: A talajvtzttlkör és rétegvíztermelés kapcsolata 13 Interaction ol r shallow water table and deep groundwater abstraction in the city of Debrecen, Hungary Marton, L. - Szanyi, J. Abstract Keywords: MARTON LAJOS SZANYI JÁNOS During the last two decades a decreasing trend of shallow water table has been observed in the surroundings of the city of Debrecen, Eastern Hungary. Some experts consider that it is the consequence of the decreasing amount of precipitation in this cycle.

. The significant descending of shallow water table is remarkable from two points of view: on the one hand it may cause damages in sylviculture and may involve loss in agriculture in some places and, on the other hand, increases the danger of contamination of deep groundwaters. Analysing the records of groundwater levels and those of the precipitation, it was pointed out that descending water table levels attribute to the deep groundwater abstraction. It was shown by geodetic measurements that a depression cone has also been developed in the source bed due to the large-scale exploitation of waters from the major confined aquifer. The cross correlation analysis of water production and water table fluctuations affirmed the interaction The studied area, located in the southern part of Nyírség, has a relatively simple geological structure. The Pleistocene sediments ranging m thickness from about 200 to 300 meters, are largely interbedded fluvial fine and coarse grained sand as well as gravel. The Lower Pleistocene sequence is the major aquifer of regional extension, overlain and underlain by an aquitard and clayely Pliocene deposits, respectively. This major aquifer provides municipal water supply in the territory, therefore it is collectively referred to as the "Watcrwork Aquifer". The Middle Pleistocene Aquifer exploited mainly for industrial water supply is also overlain by an aquitard. The Upper Pleistocene Aquifer is the source bed with water table. I Iydrodinamically the basin forms a leaky aquifer system with downward leakage. In the city of Debrecen the deep groundwater has been pumping for municipal water supply for 80 years, which has been grown exponentially since the 1950s. The groundwater abstraction from this major aquifer is fairly large: the waterwork production reaches 20-25 million cubic meters annually. The discharge is so large that the water table influenced appreciably by pumping of confined aquifer. The major aquifer is believed to be well protected against pollution because of existing of overlying aquitards. Nevertheless the aquitards are not continuous, hydraulic windows can be found in some places. On the other hand, the exploitation of deep groundwaters causes long-term non-steady-state conditions, large-scale changes in flow patterns of the groundwaters and hydraulic short circuits to shallow aquifers. Thus contaminants may penetrate to wells in deep groundwaters even if the wells are believed to be protected against pollution. It seems therefore, that exploitation of deep groundwaters should be limited. Hydrogeology, precipitation, groundwater, groundwater abstraction, cross correlation oki. mérnök, a műszaki tudomány kandidátusa, az MTA Debreceni Területi Bizottsága munkabizottsági elnöke, a Vízgazdálkodás-tudományi Bizottságnak több éven át tagja. Kutatási területe az üledékes medencék hidrogeológiája, izotóp hidrológia, numerikus hidrológia. geológus-matematikus. Egyetemi tanulmányait Szegeden a József Attila Tudomány Egyetemen és Budapesten az Eötvös Loránd Tudomány Egyetemen végezte. A Debreceni Kossuth Lajos Tudomány Egyetem Ásvány- és Földtani Tanszékén volt ösztöndíjas három éven át. Jelenleg a Magyar Geológiai Szolgálat Dél-alföldi Területi Hivatalának geológusa Szegeden Kutatási területe a geostatisztika, a felszín alatti vízáramlások modellezése.