Vízügyi Közlemények, 1987 (69. évfolyam)

2. füzet - Bratán Mária: A Fadd-Dombori üdülőterület

284 Br a tán Mária The resort-area of Fadd-Dombori by DR. M. BRATÁN (Ms), С. E. Between the village of Gerjen and the outlet of the Sió River two dead-channels are found on the right bank of the Danube River (Fig.l). They are the dead-channels of Fadd and of Tolna. The hydrographical and hydrometeorological features of the area are favourable for recreation. Especially, at the dead-channel of Fadd-with a water surface of 1 to 8 km

2, and with a storage capacity of 6.6 million m

3 at the highest permitted water level-where a considerable vacationing area came recently into being (Fig. 1) suitable for a simultaneous recreation of several thousand people. The water supply of the area is satisfactory but canalization does not exist. Wastewaters originating from the small vacation-homes are desiccated. The water regime of the dead-channel of Fadd is determined primarily by the position of the groundwater table, and secondly by the amount of precipitation. Waterhousehold balances-that are characteristic in our shallow lakes (Lake Balaton, Lake Velence)-cannot be set up in the dead-channel of Fadd. Underground inflow may be assumed as 0.175 m

3/s. Direct interconnection with the water regime of the Danube could not be observed. In the water stage time-series of the dead-channel of Fadd (Fig. 2) some characteristic fluctuations could be observed. The regime is characterized by the high-waters in spring and early summer, and by lows around the end of autumn. Annual fluctuations amounted to an average value of 0.60 m in the stages. According to a temporary water-stage control manual issued in 1983, the water level must be kept between 1.60 and 1.20 m during the first four months (I-IV.) of the year (Fig. 2). This range is decreased gradually to 1.20 and 0.80 m in September (Fig. 2). In extremely dry periods, the natural supply of water is insufficient, therefore, additional water must be introduced in the system (Fig. 3). One can take out 1.1 m

3/s from the Danube in average by a siphon at Dombori, if the high levels have a duration of 25 percent. The water supply is critical from the point of view of quality, moreover, seepage reduces its efficiency. The dead-channel at Fadd has been investigated regularly for its quality since 1969. The main canal of Paks-Fadd (Fig. 1) feeding the dead-channel of Fadd is moderately polluted on the basis of samples taken in three points of the watercourse. Its biological qualification is: mezoeutrophic. The saprobic Pantle-Buck number ranges between 2 and 2.3. For the improvement of the water quality in the dead-channel of Fadd total canalization and wastewater treatment would be needed beyond temporary partial solutions. Infiltration and desiccation are blamed first for the rather rapid deterioration of water quality and for the advancing of eutrophication. This latter is fostered by the wastewater supply received through the soil and the groundwater aquifer. * * * Le terrain de plaisance de Fadd-Dombori par Dr. BRAT AN M., ingénieur de génie civil Le long du tronçon du Danube de Gerjen á Г embouchure de Sió se trouve les bras morts danubiens de Fadd et de Tolna (voir Figure 1.). Les conditions hydrographiques, hydrologiques et météorologiques de ses zone sont trés favorables au point de vue de plaisance. Surtout la retenue d'eau á coté du bras mort de Fadd est développée et apte á la création d'une zone de repos et de récréation pour plusieures milles personnes. Il s' agit d'une zone qui se développe depuis 1959. La capacité de stockage de la retenue est de 6,6 million m

3, et la superficie du plan d'eau varie de 1 á 8 km

2 en fonction des niveaux d'eau admissibles (voir Figure 1.). La zone en question est déjà équipé par un réseau d'alimentation en eau potable, mais Г assainissement n' est pas résolu. Les eaux usées locales sont épandues.