Vízügyi Közlemények, 1948 (30. évfolyam)

2. szám - VII. Szakirodalom

(40) LOW WATER REGULATION OF THE TISZA RIVER. By B. IVÁNYI. Part I. (For figures and tables see pages 131 159 of the Hungarian text.) D. C. «27.42 (282.243.742) + 627.15 1. General statements. The River Tisza collects the waters of the eastern part of the Carpathian basin, and carries them on to the Danube. The extent of the region drained by the Tisza is 157,18« square kilometers, its hydraulic data are given in figures No. 1 and 2. In its great length and little slope the lower course of the Tisza — on a smaller scale — closely resembles, from a hydraulic point of view, the lower course of the Mississippi, and the mighty rivers of the vast plains of South America, India and China. Its valley —- once the bottom of a sea —• is a level tract of country, with hardly any descent, its main characteristic being its exceedingly wide flood area, which in some places extends for 50 km. As a result of the frequent inundations, the flood control of the Tisza valley was started in the middle of the 19th century. In order to accelerate the run down of the flood waters, the meandering course of the river was curtailed by 112 cut-offs, in consequence its lower course, originally 1213 kilometers was shortened to 760 kilometers (that is 37%). After this, over a period of several decades, the greatest flood control installations of Europe were built up, which are of world-wide significance. (2,470,000 hectares protected area, 3950 km dam, 18,000 km ditch and 104 pumping stations with a round 184 m

3/see capacity.) These mighty works of construction are generally referred to as the "Tisza Regulation"

, although in reality they do not include the fixing of the channel, the protection of the banks, nor the regulation of the shoalv fords. Previous to the regulation the entire length of the flatland section of the Tisza was navigable. Nowadays, however, regular navigation is carried on only below Szolnok, where the necessity for low water regulation first arose. The lowest recorded level of the Tisza was that of the year 1841—1842, and the "0" point of the gauges was fixed at that level. The lowest low water of the period just before the beginning of the low water regulation, was recorded in 1904, as the consequence of an extremely arid year. The lowest water levels recorded up to 1904 are given in table No. I. We can learn from these records, that through the numerous cut-offs, the low water level, compared with the pre-regulation time, sank considerably, even sometimes 3 meters. The lowering of the water level was mostly due to the sinking of the river bed, but it was also caused by the increase of the surface slope, the widening of the river bed, and by the more violent flow, the discharge of low water was diminished. The author has investigated the depth conditions of the fords previous to regulation in the entries of the Szolnak gauge over a recorded period of 30 years. If Szolnok water level sinks to cm — 30 — 60 — 110 Lowest depths of fords below Szolnok dm 18 — 19 16 12 And between Szolnok and Tiszafüred at the same time dm 16 12 9 And even below Szolnok, the minimum depth sinks to dm 10—11. With the ships of the Tisza one can transport economically to greater distances, if the depth of the river is dm 16 or therebouts. The records given in table No. II. of the duration of the water level, show how irregular is the flow of the Tisza and in consequence how essential was and still is its regulation. The frequency and the duration of the occurence of the different low waters are as follows: