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a b s t r a c tIn the Great Hungarian Plain (GHP), one of the most complex fluvial systems of Europe developed through tectonic and climatic factors and vegetation change. The aim of the present study is to summarise these controlling factors and to describe the evolution of the GHP. Special attention is paid to the latest results on late Weichselian and Holocene development in the Tisza River and their effects on the river's largest tributary: the Maros River.Several tectonically active subsiding basins existing in the GHP have determined the direction of river courses and erosionaleaccumulational fluvial processes. As a result of uneven subsidence, the river's flow routes have shifted frequently. For example, the Danube and the Tisza shifted 80e100 km, abandoning their alluvial fans where extensive aeolian processes started. Upstream from the subsiding areas, incision propagated headward, which resulted in the development of floodplain levels and terraces. Though climate and vegetation changes also simultaneously influenced the rivers' hydro-morphology, channel pattern changes were found just along the margin of the plain, and only meandering paleo-channels remained in the center of the GHP. During dry and cold periods, braided patterns appeared in the alluvial fans, most likely the result of abundant sediment supply and due to the inability of sparse riparian vegetation to stabilise the banks effectively. Based on paleo-discharge calculations, by the end of the Pleistocene the rivers of the GHP produced three to eight times more discharge than they do currently, and discharge levels continuously decreased during the Holocene. However, due to the long length of the rivers, there is a considerable time lag between the response rates of the different river sections, which makes creating paleo-hydrological reconstructions even more difficult.

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The aim of the study was to identify the abandoned channels on the alluvial fan of the Maros River and to calculate their paleodischarge. As the first step of the investigation regional equations had to be made for discharge calculations based on the earliest available discharge data for the rivers of the Tisza catchment in Hungary. Equations between discharge and channel parameters were created with high correlation coefficient. Then the paleochannels were identified on the Hungarian part of the alluvial fan. The paleochannel generations are located in continuous zones with well defined boundaries. The density of the abandoned channels varies on the alluvial fan, as some areas densely covered by channels and on other areas almost free of paleochannels. Braided, meandering and misfit channels were separated, but only the morphometry of the meandering and misfit channels were measured (width, ratio of curvature, half-wavelength and cord-length). Based on these morphometric parameters and the discharge equations the mean discharge of the channels was calculated. The greatest discharge was around 6300 m3/s while the smallest was 31 m3/s. However, several abandoned meandering channels had slightly greater bankfull discharge (700-900 m3/s) as the present-day Maros River.