The impacts of near-bed flow characteristics on river bed sediment transport under ice-covered conditions in 2016–2021

Global climate change has been projected to affect hydrology, the ice-covered flow period and river morphology (including changed sediment transport conditions) in northern high-latitude regions. To understand impact of expected shortening on bedload transport, one needs present these rivers with annually occurring ice cover. Thus, aims are (1) define impacts cover near-bed characteristics during hydrologically varying years, (2) analyse mid-winter bed potential. The analyses based Acoustic Doppler Current Profiler (ADCP: 2016–21) Velocimeter (ADV: 2020–21) measurements performed conditions sandy small (circa 20 m wide) Pulmanki River Finnish Lapland. Despite winter, occurs even harshest conditions. critical velocities shear were exceeded winters 2016–2021, occurred according measurements. Three different situations regarding velocity conditions: high measured discharges indicate throughout meander bend; low cause (3) having intermediate potential being higher at upstream inlet apex sections bend but clearly lower downstream apex. confinement by cover, i.e. bottom-fast ice, explains variation. highest section a symmetrical bend, where measurement cross-sections narrower shallower. lowest apex, channel from relatively narrow wider deeper.