River ice cover influence on sediment transportation at present and under projected hydroclimatic conditions

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Kämäri, M. et al. 2015. River ice cover influence on sediment transportation at present and under projected hydroclimatic conditions. Hydrological Processes 29 (2): 4738–4755. http://dx.doi.org/10.1002/hyp.10522

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Title: River ice cover influence on sediment transportation at present and under projected hydroclimatic conditions
Author: Kämäri, Maria; Alho, Petteri; Veijalainen, Noora; Aaltonen, Juha; Huokuna, Mikko; Lotsari, Eliisa
Date: 2015
Language: en
Belongs to series: Hydrological Processes 29(22): 4738–4755
ISSN: 0885-6087
DOI: http://dx.doi.org/10.1002/hyp.10522
URI: http://hdl.handle.net/10138/298483
Abstract: A large number of rivers are frozen annually and the river ice cover has an influence on the geomorphological processes. These processes in cohesive sediment rivers are not fully understood. Therefore, this paper demonstrates the impact of river ice cover on sediment transport, i.e. turbidity, suspended sediment loads and erosion potential, compared with a river with ice-free flow conditions. The present sediment transportation conditions during the annual cycle are analysed, and the implications of climate change on wintertime geomorphological processes are estimated. A one-dimensional hydrodynamic model has been applied to the Kokemäenjoki River in SW Finland. The shear stress forces directed to the river bed are simulated with present and projected hydro-climatic conditions. The results of shear stress simulations indicate that a thermally formed smooth ice cover diminishes river bed erosion, compared with an ice-free river with similar discharges. Based on long-term field data, the river ice cover reduces turbidity statistically significantly. Furthermore, suspended sediment concentrations measured in ice-free and ice-covered river water reveal a diminishing effect of ice cover on riverine sediment load. The hydrodynamic simulations suggest that the influence of rippled ice cover on shear stress is varying. Climate change is projected to increase the winter discharges by 27–77 % on average by 2070–2099. Thus, the increasing winter discharges and possible diminishing ice cover periods both increase the erosion potential of the river bed. Hence, the wintertime sediment load of the river is expected to become larger in the future.
Subject: rivers
ice cover
sediments
ice
climate changes
sedimentation
geomorphology
hydrodynamics
erosion
turbidity
load
simulation
hydrology
climate
water quality
prediction
future
Kokemäenjoki River
Finland
Southwest Finland
2070-2099
Subject (ysa): joet
jääpeite
jää
sedimentit
ilmastonmuutokset
sedimentaatio
geomorfologia
hydrodynamiikka
eroosio
sameus
kuormitus
simulointi
hydrologia
ilmasto
vedenlaatu
Kokemäenjoki
Suomi
Varsinais-Suomi
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