Vízügyi Közlemények, Kivonatok, 1965

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

(33) Forecasting experiences gained during the flood have been compiled in Chapter 4. The method of forecasting used during the 1965 flood is briefly described (Table XII). The errors of forecasts prepared from stage at Bratislava for Budapest and Mohács, as well as of those prepared on the basis of stage at Engelhartszell for Bratislava and Budapest, are presented in Table XIII. The difference between forecast and actual stages is seen to be small. From data on forecast peak stages (Table XV) it will be perceived that the maximum error of the forecast issued at the time of the Engelhartszell peak, i.e. 4 to 5 days before the peak in Budapest and 6 to 7 days before peak at Mohács, remained smaller than 20 to 25 cm. Average errors of 1, 2, 3 and 4 day forecasts issued during the flood period for the major gaging stations are shown in Table XVI. The mean error of daily forecasts did not increase in comparison to the mean error of daily forecasts issued during the preceeding years, and this in spite of the extraordinary stage fluctuations. The great number of modifying factors which came into effect during the 1965 flood was taken into consideration with the help of approximating estimates. Flood forecasting aids prepared previously on sound basis must be completed in the future with additional aids representing the influence of various modifying factors. Individual flood waves are known to be originated by a combination of a great number of factors. With the present method of computation procedure no allowance can be made for all of the factors, consequently no essential improvement of accuracy can be expected from this method in forecasts issued on future flood waves. It appears desirable to use in the future electronic computers for forecasting purposes, the capacity of which would permit the inclusion of all factors influencing the passage of waves. The relationship approximating most closely actual conditions could then be selected with the help of programs prepared in advance. 2, FLOODS AND FLOOD CONTROL IN 1965 OVER THE DANUBE REACHES IN NEIGHBORING COUNTRIES The development and progression of the flood over the Danube were influenced greatly by meteorological and hydrological events on neighbouring reaches of the stream and over the catchment areas in adjacent countries. The account presented on the Danube flood and the control measures taken would therefore be uncomplete without a slightly more detailed treatment of flood history over adjacent Danube reaches. A description is given for this reason on flood events in 1965 in Austria as well as on flood control measures in Czechoslovakia and Yougoslavia.