Vízügyi Közlemények, 2004 (86. évfolyam)

3-4. füzet - Konecsny Károly: A felső-tiszai közös magyar-ukrán vízrajzi távmérő rendszer egy éves üzemelésének értékelése

564 Konecsny Károly The installation of the remote sensing hydrometric system of the Upper Tisza Basin was started in Ukrainian territory (in the Sub-Carpathian area called Kárpátalja) utilising Hungarian funds. The system consists of 8 complex tele-hydrometric stations and four precipitation and temperature gauges located in high elevations at the ultra short wave transmission stations. On the 30

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h of October 2003 the Hungarian and Ukrainian heads of the relevant ministries launched the operation of the common Hungarian-Ukrainian hydro-telemetric system of the Upper Tisza Basin that was expanded to include additional 14 stations (Table T). Since this time the system have collected enormous amount of data. In Hungary, in the area of the Environmental and Water Management Directorate of the Upper Tisza (FETIKÖVIZIG), 19 telemetric water level gauges, 2 hydrometeorological stations, and 2 telemetric ground water level observation wells belonged to this system (Figure 2). By the end of

2004 the jointly developed transboundary system of the Upper Tisza Basin included 42 hydro-telemetric stations of which 20 was in Ukrainian territory in Kárpátalja (Table I, Figure 3). The system has four functional parts (Figure 3): the hydro-telemetric stations; the tele transmission network; the system's centres in Nyíregyháza and Ungvár/Uzhgorod and the connected other systems (hydrological data bases OHM and MAHAB, www.fetikovizig.hu). The system measures water level, precipitation and air temperature in five-minute intervals. The monitoring methods and the elements of the software and the hardware are identical on both Hungarian and Ukrainian territory. In the period 01 October 2003-31 October 2004 the joint Hungarian-Ukrainian telehydrometric system operated well and has increased the number of data collected in this river basin by an order of magnitude. Data were continuously transmitted and there were only a few temporary breakdowns. These included computer and software failures, ceasing of electrical supply, and the failures of the radio-transmission network at its data-collection tower. The time periods of these failures were seldom longer than 1-2 hours. The breakdown of the two ultra short wave radio transmission device, located in high mountains (Rahó-Terentyin and Pláj), was longer due to the difficult access route to these sites. Of the 8613 data measured by the 29 water-level gauging stations at 6:00h in the morning 1342 (15%) did not reach the telemetric centre of Nyíregyháza. In a monthly scale the largest datalack occurred in January 204, when 207 data were not transmitted. This situation was highly improved after the repair works of the transmission facilities made in April. The number of days with no data was determined on the basis of the ceasing of the transmission of the data measured simultaneously at the time of the morning water level gauge observations. Half (48%) of the total number of days with not data occurred in the district served by the Rahó-Tyeretyin transmission station (Figure 3). The remotely measured water levels were regularly compared to the readings of the relevant staff gauges (Figure 4). There were some significant differences between the two type of data for the following reasons: 1/ The locations of the traditional staff gauge and that of the sensor of the telemetric system are different; 2/ There are some construction errors in the foundation; 3/ The calibration of the pressure-head sensing device was inaccurate; 4/ Mechanic problems occurred at some of the recording water level gauges; 5/ There is an error in the traditional reading. Differences (errors) higher than 10 cm in the water stage data occurred mostly in such cross-sections where the water level variation is high (Figure 5). In the eight months between March and October most of the precipitation gauges were operating and therefore the state of the catchment basin could always been operatively assessed, There were no losses of data at nine stations out for the twenty, while for some further 6 stations the loss was very low (5%). Two-third of the stations operated in a reliable way (Table IT). In comparing the telemetered precipitation data to those measured by traditional gauges one should take the high spatial and temporal variability of precipitation also into consideration. The telemetric sensors of air temperature are located on the same site as those of the precipitation. Figure 6 shows the air temperature time series of two stations, one in Hungary (in