Vízügyi Közlemények, Kivonatok, 1965

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

(36) (Fig. 2). Before the middle of June groundwater stages were already very hilgh, or groundwater was under a high pressure ana, rising from the soil, large areas were inundated. Ruptures of the levees and the causes of their development are discussed in Chapter 2. The stability of the levees, but especially that of the levee subsoil was severely tested by the flood, which was unparalleled in the near past as far as the duration of high stages is concerned. The period around peaking proved to be critical for the levees, where the river stage was higher by 3.5 metres than the groundwater table. On the 15th June, immediately before the ruptures, the number of boils along the 114 km length of levee above the Vág-Danube attained 2313, of which 75 % were within 10 metres from the levee toe. Boils could be observed, however, even at distances of 350 m from the toe. The first rupture occurred on the 15th June in the levee below the Vág-Danube at Zhitavska Tony. An area of 10 000 hectares was inundated including several villages, railway and highway lines. The rupture was caused by subsoil failure and attained a length of 80 m. The second rupture occurred on the 17th June 31,7 km upstream from the town Komárom situated at the mouth of the Vág-Danube, in the vicinity of the village Csicsov (Fig. 3). An area of 55.000 hectares was inundated. The rupture was caused by subsoil erosion due to boiling and increased in length to 77 metres. At the point of the first rupture the levee was 3 m high with crest and base widths of 7 and 26 m, respectively. The corresponding dimensions at the second rupture were 5 m, 6 m and. 29 m. The slopes on the river side were inclined at 1 : 3, on the landward side at 1 : 2 and at the second rupture the levee was supported on the landward side by a 4 m wide gravel berm. Conditions after these ruptures are described in Chapter 3. Increased attention is paid to the second rupture and the progress of inundation of the protected area is demonstrated in Fig. 4. Closure of the crevasse was considered the most urgent task after the rupture. Work was greatly complicated by the foreshore forest which prevented access to the levee on water, so that a trail had to be blasted for vessels. Traffic on the levee crest was frequently interrupted by rainfall after the rupture. Current was first deflected by sinking seven rubbleloaded barges. A 671 m long ring-dyke was then built on the foreshore. Closure was completed only on the 18th dav after the rupture. The removal of water from the inundated o.reas is described in Chapter 4. The volume of water entering through the rupture and the magnitude of inundated area is plotted against time in Fig. 5. Drainage of water could be effected through sluices built into the levees of the Vág-Danube and through-cuts in the same levee (Fig. 6). After August drainage was mainly concentrated on drainage canals.