Vízügyi Közlemények, 1973 (55. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

The principal components of the project are the barrage, the reservoir and the two assoiated irrigation developments (Fig. 1.1

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9). The barrage, sited at a distance of 404 km above the mouth of the Tisza River consists of three combined structures (namely the weir, the hydroelectric station and the navigation lock), of the flood gate, the ancillary and shore works (Fig. 1.1-10). The three main structures have been constructed in a common construction pit in the flood plain, protected by an enclosure embankment (see papers 2.2 and 2.3). The principal problem for the engineers was the proximity of the Tisza River bed, the large area of the construction pit and, owing to the presence of pervious soil strata, the unwatering thereof. After extensive explorations and investigations, groundwater lowering in three stages was adopted (see paper 2.5). The correctness of the choice was demonstrated by the fact that construction work proceeded without difficulty or delay even during the exceptional flood in 1970 on the Tisza (see paper 2.8). Instead of steel sheet piling, a reinforced-concrete cutoff wall, constructed by the slurry-trench method, was adopted for controlling underseepage. The weir (see paper 2.6) consists of five spans, each 24 m long, closed by radial (Tainter) gates topped with tilting leaves. The gates are operated by oil-hydraulic hoists controlled electrically. The hydraulic design of the narrow piers is a novel solution. The powerhouse (see paper 2.7) incorporates four main generating sets of tubular design, each with a capacity of 7 MW. This is the first instance of using tubular turbines in Hungary. These were designed and manufactured in French-Hungarian cooperation. Reduced dimensions of the powerhouse and a higher efficiency can be claimed as advantages. The use of tubular turbines has resulted in saving 14,000 cu.m of reinforced concrete. The navigation lock is situated on the left-hand bank, displaced upstream relative to the weir axis. The 12 by 85 m lock chamber offers passage to 1350 ton barges. The mitre gates are operated by means of oilhydraulic jacks. Filling and emptying occurs through lateral ports. In the right-hand wall of the lock chamber a fish-pass is accommodated. Over the channel sections upstream and downsstream of the main structure the slopes are protected by a rip-rap lining dumped into a grid of precast reinforced-concrete beams. This solution has made considerable savings in construction time possible. The flood gate in the flood plain will be constructed in the second stage of development, for the full utilization of the reservoir, to pass part of the flood discharge. This spillway solution seems to be economically superior to a wider main structure. The net storage capacity of the reservoir will ultimately be 400 million cu.m, at a surface area of 127 sq.km. The headwater level will be raised in stage I to El. 87.50 m A.O.D., in stage II to El. 88.50 m A.O.D and in stage III to El. 90.50 m A.O.D. The highest stage on record in the Barrage cross section has been E. 90.73 m A.O.D. Storage by channel impoundment 262