Vízügyi Közlemények, 1986 (68. évfolyam)

2. füzet - Szekeres János: Többváltozós vízhozammérési módszer és alkalmazási lehetőségei

176 Szekeres János no confluence of a tributary and the main stream could be found, if the rating curve for steady flow, and the surface-slope curve for steady flow, in other words, if the diagram representing the relationship between surface-slope and water stage were available (Figs. 1 to 3). For the determination of slopes in water-surfaces the stages of neighbouring hydrometric stations are used. If there is a tributary between two adjecent stations (the main and the auxiliary), the water levels measured in the tributary are considered additionally as another variable to be taken into account. The method was used operationally since 1978 at 20 hydrometric stations in the Tisza-Valley for the determination of accurate discharge values. At the beginning of 1985 this method was applied for the calculation of discharges of the Danube at Budapest influenced by an ice-barrier at Budafok. The calculated and measured discharges and earlier determined discharges on the basis of old rating curves were compared in Table I. A precondition of use is that the distance between main and auxiliary stations should not be more than 10 km in case of small rivers, and 30 km if the streamflow is large. Also, water stages and discharges should be measured more accurately than otherwise.