Vízügyi Közlemények, 1981 (63. évfolyam)

2. füzet - Bartha Péterné-Bartha Péter: Az 1979. évi tiszai árvíz hidrometeorológiai viszonyai

Az 1979. évi tiszai árvíz 217 Hydrometeorological conditions during llic 1971) flood on the Tisza River by Mr. and Mrs. P. Hartha In January-February, 1979, an extraordinary hydrometeorological situation developed over the catchment area of the Tisza River, which gave rise to two major flood waves on the Tisza and her tributaries. The flood waves exceeded along several river sections the highest peaks observed thus far. The moisture feeding the heavy rains, which triggered the flood waves in 1979 originated invariably from the Mediterranean region (Mediterranean-type circulation, Fig. 2). The rainfall depths in the Tisza catchment are shown in Table I. Around the frontal zone ( Fig. 1 ) a discrete vortex developed (Fig. 3) on December, 31, owing to the pronounced deformation of the thermobaric field. The moist current in the warm segment of the two cyclones was abnormally intensive ( Fig. 4), especially in the Carpathian Basin. The t-m-t (catchment area — rain depth — rainfall duration) curve of the precipitation triggering the first flood wave is illustrated in Fig. 9. The flood hydrographe on the Tisza River, and on the Bodrog and Szamos rivers are shown in Figs. 10 and 11, respectively. On January, 1st, 1980, extremely cold air masses invaded the Carpathian Basin. The influx of cold air can be explained by the fact that the West-East oriented low pressure zone, which persisted for several days, changed into a vast cyclone with its center above the Northern-Carpathians. The cold air was transported on the back-side of the cyclone, covering the Tisza catchment with snow having a water content equivaleni to 30 — 50 mm. The precipitation triggering the second flood wave started on Ihe 24th January (Fig. 6) and was centered over the catchmcnts of the Bodrog River and the central section of the Tisza River ( Fig. 2). The precipitations reached peak intensities on the 29th January ( Figs. 7, 8). In fact, two flood waves developed, which could be distinguished clearly in the upstream gaging section Tiszabecs ( Fig. 10). The extreme height of the resulting stages will be perceived from Table II. The results of forecasting (Section 3) have been summarized in Tables IV and V. The forecast on the first flood wave was strongly disturbed by the sudden inflow of cold air. This effect was so strong that the peak at Szeged preceded by five days the peak at Szolnok (Table IV). The forecasts on the second flood wave were correct and accurate, not only for the upper — but also for the central — and lower sections of the Tisza River (Table V), since the development of the flood wave was not followed by an abnormal drop of temperature, i.e., an extreme change in weather conditions. * * * Hydrometroloyische Verhältnisse des Theisshoohu assers 1У7У von Margarita fíarthaBaiandina und Péter Bartha In Januar—Februar des Jahres 1979 entstand im Theiss-Einzugsgebeit eine ausserordentliche hydrometeorologische Lage, die an der Theiss und ihren Nebenflüssen zu zwei grossen Hochwasserwellen führte. Die Höhe der Hochwasserwellen überschritt an mehreren Strecken die bisher beobachteten Maxima. In beiden Fällen war die Feuchtigkeitsquelle des die Hochwasserwellen von 1979 auslösenden Niederschlagszyklus der Raum des Mittelmeeres („Zirkulation mediterranen Typs", Bild 2.). Die im Theiss-Einzugsgebiet gefallenen Niederschlagsmenge teilt Tafel I. mit. Rund um die Frontalzone (Bild 1.) bildete sich am 31. Dezember, infolge einer starken Deformation des thermobarischen Feldes ein selbstständiger Wirbel (Bild 3.), wobei es im warmen Sektor der beiden Zyklone, besonders aber im Karpatenbecken, zu einer ausserordentlich intensiven Feuchteströmung kam (Bild 4.). Bild 9. stellt die t —m —t Kurve (Gebiet-Niederschlagshöhe-Niederschlagsdauer-Kurve) der die erste Hochwasserwelle auslösenden Niederschlagstätigkeit dar. Die Theiss-Hochwasserwelle zeigt Bild 10, diejenigen der Flüsse Bodrog und Szamos aber Bild 11.