Vízügyi Közlemények, Kivonatok, 1965

Dégen Imre: Az 1965. évi dunai árvíz és árvízvédelmünk fejlődése

(41) high and steep rise. After the 19th June the frost line rose to almost 4000 metres and caused, in combination with repeated rainfalls floods lasting for 10—14 days especially over the lower reach of the Inn and the upper reaches of the Salzach River. Large areas were again inundated. The most conspicuous feature of the Danube flood was the long duration of very great flood discharges and consequently the extremely large volume of water carried by the flood. Chapter 3 is devoted to floods that occured between July and September. On the 5th July a flood wave travelled down the catchment of the Dráva River, and reperated floods passed down a number of water courses in the eastern cathment of the Dráva River. In August floods occurred in the eastern valleys of the Dráva system, in the catchment of the Mure, below Graz, in the catchments of the Rába and Rábca Rivers, as well as in some parts of Steiermark and Karinthia. In September Tyrol and some parts of Karinthia. the catchment areas of the Isel, Upper-Dráva. Möll and Gail Rivers were affected by floods. Concludingly it can be established that rainfalls greatly in excess of normal averages may be regarded as the main causes of flood catastrophes in 1965. but melting of snow accumulated in this year contributed greatly to flood volumes. It is interesting to note the differences between floods in different catchments of Austria, which were characterized in the southern and eastern part by extreme discharges, while at other areas, as for example along the Danube, by the extremely long duration ol great discharges. Flood probabilities in the southern and eastern parts ranged on the average from 20 to 25 years and in extreme cases to 100 years, while the Danube flood on the Vienna gage and in the Linz gage corresponded to only 15 and 25 year probabilities, respectively. 2.2 THE 1965 FLOOD IN CZECHOSLOVAKIA By Inz. M. Gyalokay and Iné. J. Szolgay ( Czechoslovakia ) (For the Hungarian text see pp. 113) In Czechoslovakia

, on the left-hand side of the Danube a total area of 185 000 hectares is protected by flood levees. The length of the levees between Bratislava and the Vág-Danube is 195 km, below the V

ág-Danube 59 km, and along the left-hand tributaries, as a protection against backwater from the Danube, 40 km levees have been built (Fig. 1). In Chapter 1, in connection with a general review of hydrological conditions, it is emphasized that in Spring, 1965 when flood waves travelled down the Danube with medium to high stages, the groundwater level and the movement of groundwaters were governed by these flood waves