Vízügyi Közlemények, 2004 (86. évfolyam)

1-2. füzet - Szalai József: A hidrológiai közelmúlt sajátosságai a talajvíz szintekben

A hidrológiai közelmúlt sajátosságai a talajvíz szintekben 167 Szabó Gy.\ Talajvízszint változása Pest belterületén. Hidrológiai Közlöny. 1960/2., pp. 106-115. 1960. Szalui J.: A talajvízszintek változása a Duna-Tisza közén a késő őszi-téli időszakban. VITUKI, 1996. * * * Special features of the near-past hydrology in the changes of groundwater levels by József SZALAI C.E. The near-surface groundwater level regime of the Hungarian lowlands is basically defined by the temporal and spatial distribution of precipitation. In some regions, however, other factors (such as the water regime of the River Danube in the Szigetköz region) may be also significant. The relationship between the precipitation in the vicinity of the observation well and the water level changes of that well can be well investigated by graphically comparing the time series of the deviation from the average of the annual precipitation to the time series of the groundwater level. Results of the regional investigations of the period 1951-2003 indicate that the cumulation of precipitationshortage and excess in the Kisalföld region cannot be well detected in the changes of the groundwater levels (Figure 1.). A closer relationship can be detected in the Kisalföld with the annual moving average. In the area of the Szigetköz the groundwater level was, before the diversion of the Danube (to the power canal of the Bős/Gabcikovó hydropower plant), basically defined by the water regime of the River Danube. In the period after the diversion of the Danube, and after the construction of the underwater weir (that was constructed for securing higher water levels and better inflow in/to the side river arms of the Danube) the state of the groundwater table was affected by a number of factors, in addition to hydrometeorological ones, such as the colmatation of the Dunacsúny/Cunovo reservoir. In other flat-land regions of the country, such as the region between the rivers Danube and Tisza, there is a marked relationship between the precipitation in the vicinity of the observation wells and the groundwater regime (figures 2 and 3). In the period 2000-2003 there were extreme weather events (Figure 4). The year 2000 was especially critical one from the point of view of the groundwater table. In the southern Hungarian lowland „Dél-Alföld" there was an exceptionally large precipitation shortage of 250-300 mm, in comparison to the average of the years 1961-1990. In the year 2001 there was precipitation-excess in the Alföld, while in 2002 areas of precipitation-shortage and excess occurred together in a capricious spatial distribution. In 2003 there was a nation-wide precipitation shortage, with a few exceptional areas. In the period 2000-2003 nearly all flatland areas suffered a loss of the groundwater resources, although the variation of groundwater levels followed a regular pattern (Figures 5., 6., 8, and 9). A small growth of groundwater resources was observed in certain districts of the region between the rivers Danube and Tisza.