Hungarian Geographical Bulletin 1/2009 [antikvár]

Strategy or disaster Flood prevention related issues and actions in the Tisza River basin Ferenc Schweitzer1 Abstract Changes in land use of the lowland landscape along the Tisza River have largely been shaped by processes that took place after flood control and regulation measures of that river. As a result fluvial accumulation has either been eliminated or restricted to the flood plain. At present humán settlements extend to somé segments of the low flood plain threatened by flood hazard. The amended Vásárhelyi Scheme focuses on raising embankments and extension of flood plain. Floods called the attention to problems that have to be solved, such as the stability of levee slopes. To prevent slope slumps it would be reasonable to start studies on flood control embankments in order to reveal sections endangered by an extreme water pressure during floods. Key words: geomorphology, flood hazards, flood plains, Tisza River Valley Rising from the Northeastern Carpathians, Tisza River flows into the Danube after covering 946 km. The catchment of the Tisza (157,186 km2) opens up toward the W and SW. Within its 700 km long section across the Alföld (Great Hungárián Plain), the water level remains below 100 m a.s.l. Along the middle and lower reaches in the plain its valley is asymmetric: geomorphologically it flows in a trough-shaped depression upon its low flood plain. Tisza River emerged in the Late Pleistocene and initially it crossed the plain with its tributary Szamos (Some§) eastward from its present-day channel. Its terraces of Pleistocene age are to be found in the latter regions. The river had been attracted to its present-day position by the Holocene depressions located east and north of Nyírség, the recent depression of Jászság and by the Szolnok-Titel trench. Its meandering channel changed frequently until the completion of water regulation, which were performed according to the concept of Pál Vásárhelyi. The flatland is rich in microrelief forms as evidenced by the presence of cut-off meanders, double and triple channels (Fig. 1). Masses of water provided by floods stepping out on the left bank between Tiszadob and Tiszafüred, flowing across 1 Director, DSc, Geographical Research Institute, Hungárián Academy of Sciences, H-1112 Budapest, Budaörsi út 45. E-mail: [email protected]