Vízügyi Közlemények, 1945 (27. évfolyam)

1-4. szám - VIII. Szakirodalom

(10) loess ridges running diagonally in an irregular grouping. Here developed hundreds of troughs and lake basins for the accumulation of the surface water. The valleys sloping at an average of one per thousand discharge the water into the flood area at Csongrád— Magyarkanizsa, and therefore this territory, protected by flood control levees against floods on the Tisza, is in fact the collecting basin of the wild waters of the adjoining plateau. Out of 4700 km

2 territory, 600 km

2 constitute flood area. The drainage water regulation of this protected area was carried out mostly by now. The regulation of the surface waters running down from the neighbouring area is, however, in its initial stage yet. The canals built before the serious damages of 1940, further the weir at Ludvár and the 4 m

3/sec. capacity pumping plant below Szeged by far did not prove satisfactory in 1940 to 1942 to discharge the water since at the weir at Algyő water can be discharged freely into the Tisza at a stage lower than + 6,20 m only. (At a higher stage water discharge must be discontinued.) On account of the unsatisfactory water drainage flood areas of great extent were under water in every one of the three years above mentioned (Fig. 1), and the settlements from inundation could be protected with great difficulties only. Moreover great areas were under water on the plateau too where the water had to be kept back in many places for the protection of the flood area. The cause of the water damages of 1940 to 1942 was mainly the very rainy weather condition. The precipitation of the years 1936 to 1942 exceeded considerably the average (Table I), and its distribution was very unfavorable in addition (Table III). From the station at Szeged it appears that back for 71 years within each period of 21 to 22 years a wet cycle of 6 to 7 years is included (framed in Table IV), and out of these series the cycle of 1936 to 1942 by far exceeded all the previous ones (Fig. 2). In causing all of the water damages the subsoil water played a great part which rose in some places above the surface (Fig. 3). On the basis of the stage curves of the subsoil water it may be established that the horizontal movement of the subsoil water did not contribute considerably to the cause of the water damages. Neither had a lesser significance the extraordinary frosts in the origin of the water damages. Especially until the melting periods of 1940 and 1942 almost the total winter precipitation accumulated and the- frozen grounds had not permitted the infiltration of the water originating from the meltings, which consequently were spread all over the surface. A safe agricultural production cannot be expected unless the drainage of the extraordinary precipitations are properly solved. Although the water regulation has already been started in the years of 1940 to 1942 it is not yet clear for what rate of run-off the canals and the pumping plants sould be built. For the calculation of the run-off examples of regulated territories of similar character, unfortunately, are not available. Therefore the author is resorting to an approximate procedure. We must endeaver to enable the farmer to start his farm work at the latest in the second half of the month of April. The volume of the precipitation water originating in the meltings of the very extraordinary years of 1940 and 1942 may be taken as a basis of the calculations. Taking into account that many lakes and other deeps with impervious soil, which are very suitable for reservoirs, are present the run-off is established at the rate of 0,2 1/sec. ha. In accordance with this calculation it is suggested that the canal at Algyő be dimensioned for the discharge of 5 m

3/sec., the canal at Dongér for the discharge of 30,2 m

3/sec., and the main canals and pumps of the Szeged system together for the discharge of 25,2 m

3/sec. of water. The construction of the canal system should be completed by 1957 since at that time another wet period must be counted with on the basis of Fig. 3. The canals will influence the movement of the subsoil water to a small degree only. Their effect may be limited to the reduction of the raising of subsoil water level after the discharge of the- surplus water becomes possible. On the other hand in average and dry years the method of the storing of water must be assured in accordance with the methods dictated by nature by appropriate locking of the canals. Only in this way may water economy properly be solved.