Vízügyi Közlemények, 1955 (37. évfolyam)

1-2. füzet - XIV. Lászlóffy Woldemár: Az árvíz előrejelzése

и новые дамбы, или укрепили в значительной мере уже существующие. Из-за водопроницаемого, элювиального грунта в основании по Дунаю стало необхомимым устранить просачивающиеся воды, обезвредить пробивающиеся родники. В конечном счете 5% защищаемых территорий по Дунаю были затоплены, что обозначало значительные потери народному хозяйству. FLOOD AND PREVENTION WORK E. Se г/ and J. Sik (Fig. and pictures on pp. 7—25. of Hungarian text. Annexes at the end of the volume) UDC 627.512+627.515 (439.1) The .gigantic Danube flood of July 1954 put the Hungarian flood prevention organization, in charge of the protection of an area of 400 000 hectares along a section of 416 km length, to a very hard test. The total length of protective works is 800 km ; almost everywhere flood stages exceeding the hitherto highest crests — except those caused by ice jams — and of very long duration had to be combated. Table I. lists the highest flood crests free from ice, Annex II. shows the development of the flood wave at the principal gauges, and Fig. 1. compares the duration of the flood with the former inundations. Annex IV. presents the areas protected by the District Water Boards controlling prevention work, as well as their lines of protection. Defence lasted from July 8 to August 1. The flood attained its highest level along Szigetköz Island downstream from Bratislava, where it was higher than the crown of the levees in several places, so that along 20 km the levees had to be topped by improvised dams (Annex I.) The Danube flows here at its entry into the Carpathian basin on a self-built alluvial cone. Its slope falls from 0,00045 to 0,00010, therefore it deposits its load and silts up its channel by 2—4 cm every year. The principal cause of the high flood level was this silting up of the channel, which conjointly with the most pervious subsoil led to numerous seepages and pipings. The first dangerous soaking of the levee near the sluice of the Moson Danube Branch at Rajka could be made harmless on July 13 by the speedy assignment of a mechanized sheet-piling unit, and the burst of the levee could be prevented by building into the channel of the Danube Branch 1000 eu. m. of stones in a few days by the assignment of considerable labour force. On July 15 and 16, immediately before the flood crest, the levee burst through hydraulic ground failure at 3 places and a fourth break was caused thereby that the high velocity flood flow was turned by the bank of an old arm against the levee and washed it off gradually (Pictures 1 — 3). Water flowing through the four breaches of 390 m aggregate width inundated 20 600 hectares and dislodged temporarily 30 000 inhabitants. (Pictures 4 — 8). There was no loss of human life. Plugging the breaches could not be started immediately for difficulties of communication and material transport, and the overflowing water subsequently filled the low-lying areas of Szigetköz, island between the Danube and the Moson Danube Branch surrounded by levees, and threatened to inundate the left-bank suburbs of the City of Győr (Annex III.). It was attempted to rehabilitate the old levee on the border of the city to a protective work by the assignment of a large number of earth-moving machines, but the water broke through the pervious subsoil and flooded one suburb of Győr, Bévfalu. (Pictures 8 — 14.) Along the oth?r sections flood prevention work was successful. Cooperative effort of the country saved the railstation of Komárom and the principal highway. (Picture 15.) At Almásfüzitő construction of the levee protecting the works and settlements was not entirely completed ; with a large number of earth-moving machines 18 000 eu. m. of earth were built into the levee in a few days. (Picture 16). Much work was to be done in the town of Esztergom too, where levees had to be topped as well. North of Budapest tough flood prevention work was done to save crops on sections where the narrow floodland is only protected by low, so-called summer levees. South of Budapest levees are built to control flood's caused by ice