TY - JOUR
T1 - Advance, Retreat, and Halt of Abrupt Gravel-Sand Transitions in Alluvial Rivers
AU - Blom, Astrid
AU - Chavarrias Borras, Victor
AU - Ferguson, Robert I.
AU - Viparelli, Enrica
PY - 2017/10/16
Y1 - 2017/10/16
N2 - Downstream fining of bed sediment in alluvial rivers is usually gradual, but often an abrupt decrease in characteristic grain size occurs from about 10 to 1 mm, i.e., a gravel-sand transition (GST) or gravel front. Here we present an analytical model of GST migration that explicitly accounts for gravel and sand transport and deposition in the gravel reach, sea level change, subsidence, and delta progradation. The model shows that even a limited gravel supply to a sand bed reach induces progradation of a gravel wedge and predicts the circumstances required for the gravel front to advance, retreat, and halt. Predicted modern GST migration rates agree well with measured data at Allt Dubhaig and the Fraser River, and the model qualitatively captures the behavior of other documented gravel fronts. The analysis shows that sea level change, subsidence, and delta progradation have a significant impact on the GST position in lowland rivers.
AB - Downstream fining of bed sediment in alluvial rivers is usually gradual, but often an abrupt decrease in characteristic grain size occurs from about 10 to 1 mm, i.e., a gravel-sand transition (GST) or gravel front. Here we present an analytical model of GST migration that explicitly accounts for gravel and sand transport and deposition in the gravel reach, sea level change, subsidence, and delta progradation. The model shows that even a limited gravel supply to a sand bed reach induces progradation of a gravel wedge and predicts the circumstances required for the gravel front to advance, retreat, and halt. Predicted modern GST migration rates agree well with measured data at Allt Dubhaig and the Fraser River, and the model qualitatively captures the behavior of other documented gravel fronts. The analysis shows that sea level change, subsidence, and delta progradation have a significant impact on the GST position in lowland rivers.
KW - alluvial rivers
KW - gravel bed rivers
KW - gravel front
KW - gravel-sand transition
KW - mixed-size sediment
KW - sand bed rivers
UR - http://www.scopus.com/inward/record.url?scp=85031418266&partnerID=8YFLogxK
UR - http://resolver.tudelft.nl/uuid:842174ef-df17-45ae-b558-6920b8171548
U2 - 10.1002/2017GL074231
DO - 10.1002/2017GL074231
M3 - Article
AN - SCOPUS:85031418266
SN - 0094-8276
VL - 44
SP - 9751
EP - 9760
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 19
ER -