Vízügyi Közlemények, 1999 (81. évfolyam)
4. füzet - Szlávik Lajos-Galbáts Zoltán-Kiss Attila-Kisházi Péter-Rátky István: A Fehér-, Fekete- és Kettős-Körös árvizei, árvízvédelmi rendszere és a Kisdelta szükségtározó
606 Szlávik L.-Galb áts Z.-Kiss A .-Kisházi P.-Ràtky 1 . The regulation works started first on the Fehér-Körös , in 1833. A substantial mistake was made by not leaving any space for the natural development of the river and this situation caused many problems during the past one and half century. Generally speaking, the regulation of the River FehérKörös can be considered successful. Floods are passing without causing disturbances and the slope conditions correspond to the channel bed material. However, the very narrow flood berm, the rightbank levee, which runs closely and parallel to the collapsing high banks, can be considered a mistake. The works of the rivers Kettős- and Hármas-Körös mostly reached their objectives. Flood waves of the Körös rivers reach the confluence with the River Tisza (at Csongrád) earlier than those of the Tisza. This situation stems from the much shortened length of the Körös rivers, which was originally four times longer than the length of the valley and now the length of the river is only few km longer tan that of the valley. The width of the flood channel, the flood berm, is sufficient, although the track of the levees could have been more favourable at certain locations. High floods of the Körös river system had caused, until 1889, substantial levee failures, without exception: there were 14 levee failures in 1876, 85 in 1879, more than 30 in 1881 and 14 in 1888. In the spring of 1895 there were 3 high flood, of which the one in April exceeded the level of the flood of 1888, but there were no levee failures, since the most important elements of the flood control system of the rivers Fehér-, Fekete- and Kettős-Körös have been completed by 1890. The flood of 1895 stayed already within the levees, due to the successful flood control operations. Later in 1913, 1915 and 1919 there were floods exceeding the earlier maximum water stages, but they all stayed within the levees (Table III.). After the Trianon (Versailles) treaty, which cut the area of Hungary to one third of the earlier size, a substantial number of the water associations of Hungary fell outside the new country borders and the area of some of them were split into two or even three parts by the new borders. This situation had a heavy impact on the flood control system: the once unified technical system and the control organisation were split into parts. After the 2 n d World War, until the high flood of 1966, there were no development works, worth mentioning, made in the flood control system. However, in the past three and half decades, considerable development of the flood control system of the Fehér-, Fekete- and Kettős-Körös river system has been achieved (Figure 2.). There were extremely high and fierce floods in the Fehér-, Fekete- and Kettős-Körös river system in 1966, 1970, 1974, 1981 and 1995 (Table II.). Each of these floods caused levee rupture or necessitated emergency storage. Nevertheless, very useful experiences were gained during these floods, initiating significant development work of the flood control system. In the Fehér-, Fekete- and Kettős-Körös river system there were 18 significant development projects made since 1966 (including those approved for implementation by the end of the year 2000). The emergency flood storage reservoirs of Mérges and Mályvád (Figure 3.) were built for improving the flood safety of the settlements near to the rivers. The hydrological regime of the Fehér-, Fekete- and Kettős-Körös rivers varies within extremes. Water level fluctuation reaches, and sometimes exceeds, 10—11 m (Table III.). In the period 1901—1999 there were 187 floods of the Fehér-Körös, the peak of which was higher than the level corresponding to level I. flood defence preparedness. On the River Fekete-Körös 204 flood waves of peaks higher than the level I. Preparedness of the gauge Remete was registered (Table IV.). Flood hydrographe of the Fehér- and Fekete-Körös rivers, which have exceeded the level I. flood-defence preparedness in the 20 1 Century, are shown in Figures 4 and 5.. In the 20 t h Century there were 17 floods of these rivers, which can be considered significant ones from some point of view (Table II.), such as: their consequences, the significance of the related flood defence experiences in improving the flood control system. These floods occurred in the following years: 1913, 1915, 1919, 1925, 1932, 1940,1962, 1966,1970, 1980, 1981, 1988,1989, 1995, 1999. Hydrographs of these significant floods in the sections of the gauges of Gyula and Remete are shown in Figures 7. and 8.
