TY - JOUR
T1 - Bar pattern and sediment sorting in a channel contraction/expansion area
T2 - Application to the Loire River at Bréhémont (France)
AU - Cordier, Florian
AU - Tassi, Pablo
AU - Claude, Nicolas
AU - Crosato, Alessandra
AU - Rodrigues, Stéphane
AU - Pham Van Bang, Damien
N1 - Accepted author manuscript
PY - 2020
Y1 - 2020
N2 - Bars are large sediment deposits alternating with deeper areas that arise from alluvial river bed instability and forcing. The present study aimed at investigating the combined influence of flow and longitudinal width variations on the co-evolution between bar pattern and sediment sorting in a sandy-gravel river reach. To this goal, a fully non-linear 2D numerical model was developed to reproduce the morphodynamic behavior of bars in a reach of the Loire River consisting in a typical channel expansion/contraction. Numerical results showed that varying water discharge promoted a competition between low and high bar modes: i.e., from alternate to multiple bar patterns. Low bar modes were associated with coarse sediment over bar tops and fine sediment in pools, and this sorting pattern was inverted for higher bar modes. Surface sediment was coarser and the degree of sediment sorting was greater after periods of low than high flow. Due to high sediment mobility, sediment sorting did not significantly modify bar morphodynamics.
AB - Bars are large sediment deposits alternating with deeper areas that arise from alluvial river bed instability and forcing. The present study aimed at investigating the combined influence of flow and longitudinal width variations on the co-evolution between bar pattern and sediment sorting in a sandy-gravel river reach. To this goal, a fully non-linear 2D numerical model was developed to reproduce the morphodynamic behavior of bars in a reach of the Loire River consisting in a typical channel expansion/contraction. Numerical results showed that varying water discharge promoted a competition between low and high bar modes: i.e., from alternate to multiple bar patterns. Low bar modes were associated with coarse sediment over bar tops and fine sediment in pools, and this sorting pattern was inverted for higher bar modes. Surface sediment was coarser and the degree of sediment sorting was greater after periods of low than high flow. Due to high sediment mobility, sediment sorting did not significantly modify bar morphodynamics.
KW - Alluvial bar
KW - Fluvial engineering
KW - Fluvial morphodynamics
KW - Heterogeneous sediment
KW - Numerical modeling
KW - Sediment transport
UR - http://www.scopus.com/inward/record.url?scp=85081397773&partnerID=8YFLogxK
U2 - 10.1016/j.advwatres.2020.103580
DO - 10.1016/j.advwatres.2020.103580
M3 - Article
AN - SCOPUS:85081397773
SN - 0309-1708
VL - 140
JO - Advances in Water Resources
JF - Advances in Water Resources
M1 - 103580
ER -