Discharge calculation of paleochannels on the alluvial fan of the Maros river, Hungary

Abstract

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.

Reconstruction of Palaeo-hydrology and fluvial architecture at the Orosháza palaeo-channel of River Maros, Hungary

“…Bankfull discharges calculated by different approaches showed considerable variance (Table 3). In terms of the meandering reach discharges calculated on the basis of (Leopold and Wolman, 1957;Mackey 1978) were considerably, almost 50 % lower than the value received using the region-specific formula of Sümeghy and Kiss (2011). By using the equation of Dury (1976), setting up a relationship between discharge and cross-sectional area in case of meandering rivers, the received result was clearly and significantly overshooting the previous values.…”

“…The apex of the fan is at 130 m asl while its rim is between 80-85 m asl. The slope of the fan is not uniform, usually it is between 20 and 30 cm/km however near the edge there is a belt where it can reach occasionally 50 cm/km (Sümeghy and Kiss, 2011).…”

“…As a consequence, post formational loess deposition could not be significant. Partly because of this and due to supposedly fast avulsion processes (Sümeghy and Kiss, 2011) forms are still sharp and well detectable. For the present research two study sites were investigated, one on the braided, the other on the meandering section of the palaeo-channel (Fig.…”

Morphological and hydrological characteristics of paleo-channels on the alluvial fan of the Maros River, Hungary

“…Gábris (1986) suggested that from Laczay's classes only the so called developed and well-developed meanders should be used in paleo-discharge calculations. Finally, pa-laeo-discharges were calculated applying the regional equations developed by Sümeghy and Kiss (2011).…”

“…XII and XIII) fall into the developed class, while the remaining seven zones are well-developed (Table 3). For all zones the paleodischarge calculations were carried out using the mean horizontal channel parameters and the formerly created regional equations (Sümeghy and Kiss, 2011).…”