Vízügyi Közlemények, 2002 (84. évfolyam)
2. füzet - Tóth Mária: Mikor fakadnak újra a tatai források?
210 Tóth Mária Due to the subsidence of water levels the springs of the Lake Öreg became sinks and other smaller springs have also acted similarly. The loss of pressure-head of the main karstic aquifer resulted in the increase of free (open) karstic water surfaces. From the second half of the year 1990 the pressure-head of the main karstic aquifer started to rise again also in the Tata region (Figure 3.). The reappearance of the first spring was detected in the spring-lake Katona of Fényes Fürdő. The yield of the spring was measured as 0.135 m 3/s on the 12 t h of March, 2002. Nevertheless, there are some problems encountered in the case of the rebirth" of the springs. The originally marshy, wetland areas were built in and the authorities releasing the construction permits did not consider the possibility of the rebirth of the springs. The reconstruction of the former drainage system of the endangered parts of the town became an urgent task. The regeneration process of the karstic aquifer was accelerated by the wet years of 1994—95 and 1996-99, when the precipitation and infiltration was by 20-20% higher than in the average years. The marked decrease of both industrial and drinking water abstraction rates, since about 1990, also enhanced this regeneration process. The solution of these problems is facilitated by the flow model of the Tata region, which can predict the rise of karstic water levels for the time horizon of 2010. The time of reappearance of the springs and their discharges can also be forecasted. This local hydraulic model can consider the details of the local features and thus can give more accurate prediction. The hydraulic modelling of karstic areas has serious drawbacks relevant to the fragmented type of the aquifers and their high variability. In the case of the karstic aquifers of the mountain DKH, however, the karstic water observation network, consisting of about 200 wells and having about 30 years long records, provides significant help. The contour-line, map of the Mesozoic base-mountain (Figure 4.) and the topographic map of the terrain (Figure 5.) also supports modelling attempts. The time series of measured and model calculated values are compared in Figure 6, indicating a good fit. The predicted water level time series, up to the year 2010, is shown in Figure 7. It is evident that the curves flatten-out, when the springs of Fényes will rise again and their discharge increases with the time. Figures 8 and 9 show the calculated hydraulic potential values, relative to the terrain level, for the years 2005 and 2010, respectively. Variation of spring discharges, as predicted by the model, is shown in Figure 10. The reliability of the model is proven by the fact that the points of time of the predicted and actual reappearance of the spring Fényes are very close to each other. Namely, the water level of the spring Fényes (Katona) reached the overflow sill level ( 1 20 m.a.B.S.) in April 2002, while the time predicted by the model was three months earlier. The likely explanation of the diffierence is that for the year 2001 the model used not the actual hydrometeorological input data, but the average ones and the actual infiltration must have been lower than the average. * * * Wann werden die Quellen von Tata wieder Wasser schütten? von Mária TÓTH Die Karstquellen-Gruppen der Stadt Tata stellen eine der bedeutendsten Anzapfungen des Hauptkarstwasser-Reservoirsystems des Transdanubischen Mittelgebiiges dar (Bild 1). Laut der Anfang des vorigen Jahrhunderts stattgefundenen Einschätzungen hat ihre Gesamtschüt-
