Vízügyi Közlemények, Kivonatok, 1965
Dégen Imre: Az 1965. évi dunai árvíz és árvízvédelmünk fejlődése
THE 1965 DANUBE FLOOD AND THE DEVELOPMENT OF FLOOD CONTROL IN HUNGARY By I. DÉGEN, Civ. Eng. (For the Hungarian text see pp. 5) The 417 km long Hungarian reach of the Danube river was exposed to extraordinarily high waters for a period of four months in 1965. Over a length of 390 km peak .stages during the six flood waves surpassed highest stages so far on record and presented a test of unparalleled duration for the protecting capability of the levees, for the agencies responsible for flood contrcl and for the ten-thousands of men mobilized for the defence of levees against the extreme highwater. Crevasses of the levees could be prevented by resorting to up-to-date methods of flood protection only. Chapter 1.1 deals with the main data and causes of the flood. The 1965 flood was made extraordinary by the height duration and runoff volume of successive flood waves. Over the reach above the characteristic change of slope of the Hungarian Danube, i.e., above the village Gönyü (Fig.3), the flood peak approached, but did not attain the highest ice-free stage experienced during the 1954 highwater. However, over the entire Hungarian and Yougoslav Danube reach below Gónyü, design stage determined by the 1954, 1895 and 1897 floods were surpassed (Fig. 2). It is interesting to note from the profile showing peak stages (Fig.3) that the slope of the 1965 flood over almost the full length of the Hungarian Danube was flatter than that of the 1954 highwater. The extremely long duration of the flood is illustrated well in Fig.4, in which durations of past major floods are compared and from which it is to be seen that the 1965 flood exceeded substantially in duration the 1954 flood and even the very long 1926 flood. The extreme duration of the flood will be appreciated by considering that the levee foreshores at Mohács were inundated during the 1954 flood for 27 days, in 1926 for 81 davs, while during the 1965 flood for 128 days. One of the most important flood parameters is the discharges carried by individual flood waves and the total flood runoff. The character of the 1965 flood is perhaps best reflected by the trends of the stage- and discharge hvdrographs (Fig. 6) and by the vast runoff volume conveyed in this period (Fig. 5). From the beginning of highwater, from March 26 to
