Vízügyi Közlemények, Kivonatok, 1965

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

1. THE DANUBE FLOOD IN SUMMER 1965 1.1 HYDROLOGICAL CONDITIONS BEFORE AND DURING THE DANUBE FLOOD By K. Body, meteorologist, J. Csoma, Dr. Z. Károlyi, J. Szilágyi, Civ. Engrs. (For the Hungarian text see 51) From a survey of past floods on record it will become apparent that the flood wave which passed down the Danube in Summer, 1965 surpassed as regards both stages and duration all previous ice-free floods on the Hungarian reach of the Danube. The flood wave was occasioned by an adverse combination of meteorological circumstances. Hydrometeorological causes of the 1965 flood are described in Chapter 1. Owing to the absence of mild periods during the winter period, stages over the Hungarian Danube reach were exceedingly low (below 20 per cent) in the first half of March, in spite of the considerable amounts of precipitation which fell on the catchment area. In the period between the 1st October and 15th March the average runoff was no more than 1900 cu.in/sec and remained thus below the long-term average of 2360 cu.m/sec. The low rate of runoff during the winter period provided the first warning on the accumulation of extraordinary water reserves over the upper catchment in the headwater region. In the situation described above, the meteorological factors — rise of temperature and rainfall — which govern the regime of the Danube, ensued in a very adverse succession (Figs. 1—3, Tables I

—V). Under their combined effect flood waves of successively higher stage travelled down the river after the middle of March. Over the milder slope of the" Hun-