Morphometry of Paleochannels of the Rostov Lowland (Central European Russia)

The Rostov Lowland features numerous ancient paleochannels that are clearly visible on satellite images and are located outside the meandering belts of the main rivers. Notably, three generations of paleochannels larger than the current river meander are associated with the Usty–Kotorosl river system. The reasons for their increased size, their isolation from the modern river network, and the presence of multiple generations remain unclear. Resolving these questions could shed light on the historical development of the lowland during the Late Pleistocene and Holocene, including establishing connections between paleochannels and nearby lake Nero. This study examines the morphometric parameters of these paleochannels, comparing them with modern river meanders. It analyzes longitudinal profiles along the channels and floodplains of both ancient and modern rivers, offering hypotheses about past configurations of the river network and factors driving its reorganization. The findings indicate that most paleochannels are approximately two or three times as large as their modern counterparts–distinguishing them from other large paleochannels within the Volga River basin. A new review of remote sensing data enabled a comprehensive tracing of a paleochannel through which the Usty River once flowed into Lake Nero's basin. Small meander cirques within this paleochannel have parameters similar to those of current river meander. The increase in the catchment area of Lake Nero led to the formation of large paleochannels by the Vyoksa River. The small size of modern meander in the upper reaches of the Kotorosl River has previously led to misinterpretations regarding paleochannel sizes. The characteristics of longitudinal profiles along the Usty–Kotorosl river system suggest that change of the Kotorosl River's valley occurred relatively recently, transitioning from its ancient to modern river valley.

river bed deformation, paleohydrology, internal delta, river sediments, river gradient, ancient valley, large palaeomeanders, Holocene, drainage changes