Vízügyi Közlemények, 1992 (74. évfolyam)

3. füzet - Pálfai Imre: Az 1940-42. évi katasztrofális belvízjárás emlékezete (Szászhelyi Pál és Papp Ferenc hozzászólásával)

Az 1940-42. évi katasztrofális belvízjárás emlékezete 257 Trümmer A.: Összefoglalás az országos árvíznél szerzett tapasztalatokról és a teendó intézkedésekre vonatkozó javaslatokról. Vízügyi Közlemények. 1941. 1-2. szám. Trümmer A.: Az 1940-42. évi vízmentesítési munkálatok. Vízügyi Közlemények. 1945. 1-4. szám. * * * Remembrance of the catastrophic inland excess water inundation of 1940-1942 by Dr. Imre PÁLFAI, С. E. On the springs of 1940, 1941 and 1942 inland excess waters originating from melting snow had inundated 5000 sqkm, 4000 sqkm and 6000 sqkm areas, respectively, in the flat landes of Hungary (Fig. 2.). Mostly various areas of the Hungarian great plains "Nagy Alföld" were involved (Figures 1., 2. and 3.). Abundant summer and autumn rainfalls in the years 1940 and 1942 amplified the problem. Demages were enormous in spite of the highly intenzified damage fighting operations. Agricultural production was by 15-25% smaller, in each of the three years, that the average of the past decade. Damages to buildings and to the transportation network were also substantial. There were human victims of the excess water too. The extreme conditions were the result of the combined effects of several excess water generating factors, of which each one reached extreme values, in the period of concern. The thick snow cover that had accumulated during the winter of 1939/4 (Fig. 6.) melted abruptly. Substantial thaw inducing rainfall had further increased the already enormous runoff volume that could not infiltrate into the deeply frozen soil (Fig. 7.). The thus created large water surfaces were practically maintained throughout the year due to the almost uninterrupted summer rains (Fig. 8.). There was much precipitation in the winter of 1941/42 too, the bu Ik of which fell in the form of rain. In this period excess water was mainly due to the groundwater table that rose above groundsurface level over huge areas. In the Eastern part of the Nagy Alföld the summer of 1941 was also rainy (Fig. 9.). This caused further inundations and raised the groundwater table to even higher levels (Fig. 10.). Even more snow, than in the previous two years, fell in the winter of 1941/42 associated with extremely cold weather that resulted in deep soil frost (Fig. 12.). The groundwater table was very high and enormous areas became inundated in spite of the relatively slow melting process. The concept of "winter excess water index" has been introduced in this study, that combines all excess water generating factors into a single measure. In Eq. 1., describing the index, factors accounting for the water loading (sum of precipitation water during the winter, maximum snow depth) are in the nominator, while factors affecting the water bearing capacity of soil (ground water level in October and depth of soil frost in January) are in the denominator. The value of this index has been calculated for a period of sixty years (1931-1990) for two test areas; - one in the area between rivers Danube and Tisza, and the other one in the area between rivers Körös and Maros. For the former the results arc graphically illustrated in Fig. 13. while Table I. shows the index values in order of magnitude, marking the above discussed three winter periods. The winter of 1941/42 ranks in the first place, while that of 1939/1940 is the second one. The respective values of an index, the "summer excess water index", of similar character were the highest - on the basis of the same 60 year record - in 1940, while 1941 was ranked to the third place. It can be thus concluded that extreme weather conditions, in respect to both winter and summer excess inland water generation, were prevailing in the period of 1940-1942. Although the probability of return of such conditions is low, the respective authorities should be prepared for preventive and control actions even in these cases. * * +