Vízügyi Közlemények, 1999 (81. évfolyam)

1. füzet - Konecsny Károly: Az Erdélyi-fennsík és a hozzátartozó hegyvidék vízháztartása

Az Erdélyi-fennsík és a hozzátartozó hegyvidék vízháztartása 117 The analysis of average runoff was made on the basis of the discharge data of 158 river gauging stations (Table V.). Annual mean runoff values varied between 45 mm and 1840 mm, that is the ratio of minimum to maximum is 1:40 (Table VI., Fig. /.). Five regions were distinguished, in which runoff varied differently in function of the elevation above sea level (Fig. 6.). Gradient of runoff increased with the elevation. The highest gradient 200 mm/100 m was observed in the elevation range 1,000-1,200 m above sea level. The highest runoff, exceeding 1000 mm, was found in the northern slopes of the Fogaras snow-capped mountain, in the souther slopes of the alpine mountains of Cibles and Randai, in the Kelemen- Görgényi mountain, in the western slopes of Hargita and in the catchment of the River Aranyos in the Erdélyi-Szigethegység (Fig. 7.). The lowest average runoff of less than 50 mm was found in the western part of the High-plains of Erdély, where the effect of descending foehn type air masses can be felt. Monthly and winter- and summer half-yearly average runoff data were also analyzed (Table VII). It was found that the summer half-yearly runoff is 50% higher (60-80% in the higher mountains) than the winter half-yearly one. The ratio of them, however, varies unevenly (Fig. 8.). It was shown that in large areas of the Basin of Erdély the coefficient of variation (Cv), indicating the variability of runoff, is in a range (0.45-0.70) which is characteristic to the water regime of the Hungarian great plains, rather than to hilly land (Fig. 9.). Although no full coincidence in time was found, the number of runoff cycles is the same as the number of sunspot cycles (the time lag was 1-3 years, Fig. 10.). Distribution of runoff according to its components, that of the multiannual surface- and subsurface runoff (Figs 11 and 12.), was also analyzed. Runoff coefficients calculated with the corrected precipitation (á

c) varied over extremely wide ranges (0.09-0.94) as shown in Fig. 13. In the Basin of Erdély the corrected multiannual precipitation was 846 mm of which 627 mm (67%) is the évapotranspiration, 218 mm (26%) the runoff in the river channels of the rivers Szamos, Maros and Olt. Runoff consists mostly of surface runoff (70%), while subsurface runoff is only 30 %. Interflow plus infiltration (e.g. water flowing through the soil and thus potentially available for plants) amounted to 693 mm in average (Table VIII.). Precipitation of the growing season was twice as high as that of the winter half-year. Within this the months of the most intensive water exchange were May-June, with the highest precipitation (40% of the annual one) and évapotranspiration (43%). Nevertheless the highest runoff is expected, due to snow-melt, in March-May. The Basin of Erdély and the adjoining mountains are split into four "wetness regions" on the basis of the components of the annual water budget and thermal-energy conditions. These are (Fig. 14.): zone of abundant wetness (14% of the area), zone of ample wetness (18%), zone of variable wetness (53%), and zone of water shortage (14%). The theoretical total surface and subsurface water resource is 12 milliard m

3/year of which 9.97x 109 m

3/year is surface runoff (amounting to 27% of the total water resources of Rumania). In spite of this surface water resources are decreased to the half in drought periods. Groundwater levels are also decreasing and in the areas of low precipitation serious water shortage is faced. Wasserhaushalt der Siebenbürgischer Platte und des dazugehörigen Berglandes von Dr.-Geogr. Károly KONECSNY, PhD Die Siebenbürgische Platte und das hydrographisch dazugehörge Bergland liegen im Osten des Karpatenbeckens, in der Mitte Rumäniens. Die Ausmaße des Untersuchungsgebietes liegen in nordsüdlicher Richtung bei 260 km, in west-östlicher Richtung bei 290 km (Bild /), seine Flächengröße ist 45.440 km

2. Seine hydrogeographischen Grenzen verlaufen i.a. entlang der 1500-2500 m hohen, meistens aus Kristallschiefer bestehenden Bergklämme, die gleichzeitig die Wasserscheiden der drei