Vízügyi Közlemények, 1973 (55. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

part by concrete slabs prefabricated at the construction site, over some part by rip-rap contained by a grid of r.c. beams. Some transition surfaces have been lined with hand-placed rubble and cut stone (Fig. 2.1—9). The former bend in the Tisza River — through which the cut has been excavated — was closed while the excavation of the cut was under way. Channel closure was effected over a rubble mound dike on the downstream side with material obtained from the cut excavation. The upstream part of the closed channel will serve as winter harbour. 2. The reservoir The backwater reach created by the Kisköre Barrage extends to the tailwater of the Tiszalök Barrage 120 km upstream. Over the 40 km long lower section the reservoir is formed by the wide flood plain confined by levees between which impoundment will be effected (see Fig. 2.1

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1 ). The useful storage volume in the reservoir between Els. 88.00 and 90.50 m A.O.D. is round 300 million cu.m In the final stage the retention level will be raised to 91.20 m A.O.D.

, increasing the storage capacity to round 400 million cu.m. The lake created has a surface area of about 127 sq.km at a maximum width of 6 km and 2.5 (later 3.2) m average depth. Over the impounded reach the strengthening of flood levees proved necessary. The freeboard of the levees is 1.5 m above the flood stage of 1% calculated probability and 2.0 m above the perspective retention level. The levees have been widened to 6.0 m crest width (Fig. 2.1—10). The effects of extended high storage levels have been offset by a larger levee cross-section, by a reed berm to control wave action and by a system of intercepting canals designed to collect and drain seepage waters. The same system of intercepting canals affords increased drainage capacity for surface runoff waters in the area protected. Sections of the intercepting canals where the impervious top cover is not penetrated are supplemented by pressure relief wells filled with filter gravel and extending down into the first water-bearing layer. Over the backwater rearch, channel improvement works in the interest of navigation include regulation measures, slope protection and the cutting of two bends. 3. The main irrigation canals The most important components in the distribution network are the Nagykunság and Jászság irrrigation canals, delivering water to the Nagykunság and Jászság irrigation projects (see Fig. 2.1—1). The Nagykunság main canal branches off immediately upstream of the barrage on the left-hand bank of the Tisza River. The conveying capacity of 80 cu.m,/sec is designed to deliver irrigation water to 126,000 hectares in the Nagykunság irrigation projects and to supply water in the future to the more distant Körös Valley. The supply is mostly by gravity. 272