HOLOCENE PALEOMEANDERS ALONG THE SEJM RIVER, RUSSIA

The geometries of three abandoned paleomeanders along the Sejm River i n western Russia are used to estimate former discharge characteristics and rates of meander migration during the last 5000 years. The presen tly active channel has a mean annual discharge of 71 m3s-1, while the estimated mean annual discharges of the paleomeanders range from appro ximately 90 to 135 m3s-1. Based on radiocarbon ages of channel-fill de posits, paleomeanders 'a' and 'b' were abandoned approximately 4000 to 5000 years ago, and paleomeander 'c' approximately 2000 years ago. Th ese ages produce an average rate of meander migration of 500 m per 200 0 years. Periods of meander abandonment correlate well with estimated ages of episodes of increased flooding for the Dniepr basin, of which the Sejm River is a tributary, suggesting that climatically-driven cha nnel change may have been broadly synchronous in the region.