TY - JOUR
T1 - The role of sediment transport in the mechanics of jökulhlaups
AU - Fowler, A. C.
AU - Ng, F. S.L.
PY - 1996
Y1 - 1996
N2 - The classical theory of jökulhlaups used Röthlisberger's earlier theory of ice-channel drainage to describe the development of the flood Hydrograph. This theory has some drawbacks: the mechanism of initiation (breaking the seal) is opaque, the Manning roughness coefficient is too large and the hydrographs can reveal a sudden switching from channel opening to channel closure which is not simulated by the model. In this paper, we examine these features by exploring a more detailed model, which takes into account the physics of sediment erosion and its effect on channel morphology. We propose a theory in which channels need not be semicircular, but have shapes determined by a local balance between closure and melting, and in which erosion of the tunnel margins is taken into account; in particular, we derive theoretical predictions for sediment discharge, and we also propose a mechanism whereby the pressure seal over the caldera rim at Grímsvötn in Vatnajökull, Iceland, can be broken when the lake-level water pressure is still some 6 bar below the maximum overburden ice pressure.
AB - The classical theory of jökulhlaups used Röthlisberger's earlier theory of ice-channel drainage to describe the development of the flood Hydrograph. This theory has some drawbacks: the mechanism of initiation (breaking the seal) is opaque, the Manning roughness coefficient is too large and the hydrographs can reveal a sudden switching from channel opening to channel closure which is not simulated by the model. In this paper, we examine these features by exploring a more detailed model, which takes into account the physics of sediment erosion and its effect on channel morphology. We propose a theory in which channels need not be semicircular, but have shapes determined by a local balance between closure and melting, and in which erosion of the tunnel margins is taken into account; in particular, we derive theoretical predictions for sediment discharge, and we also propose a mechanism whereby the pressure seal over the caldera rim at Grímsvötn in Vatnajökull, Iceland, can be broken when the lake-level water pressure is still some 6 bar below the maximum overburden ice pressure.
UR - http://www.scopus.com/inward/record.url?scp=0030424992&partnerID=8YFLogxK
U2 - 10.3189/1996aog22-1-255-259
DO - 10.3189/1996aog22-1-255-259
M3 - Article
AN - SCOPUS:0030424992
SN - 0260-3055
VL - 22
SP - 255
EP - 259
JO - Annals of Glaciology
JF - Annals of Glaciology
ER -