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SUMMARY:Glacier outburst floods: spatial and temporal evolution - Dr Jonat
 han Carrivick\, Leeds University
DTSTART:20130522T153000Z
DTEND:20130522T163000Z
UID:TALK41510@talks.cam.ac.uk
CONTACT:Steven Palmer
DESCRIPTION:Glacial lake outburst floods affect ice dynamics\, produce dis
 tinctive and widespread onshore and offshore geomorphological impacts and 
 are a hazard to populations and infrastructure. This presentation will fir
 stly review the status of research into the occurrence of glacier outburst
  floods\; those in alpine mountain ranges\, those from ice sheet margins a
 nd those from subglacial volcanic eruptions. It will then detail quantific
 ation of the evolution of a single outburst flood from flume\, field and n
 umerical model analyses. It will be shown that glacier outburst floods are
  initially controlled by a short acceleration due to the depth of impounde
 d water. Channel flow quickly converges to an inertial regime and thence t
 o a viscous regime dominated by channel bed friction. Outburst floods that
  enter intermediary lakes are dramatically attenuated in terms of propagat
 ion whilst basin filling proceeds to the outlet level\, dissipated of ener
 gy due to considerable flow recirculation during the rising stage of the f
 lood\, and after overtopping of the outlet are moderated in terms of peak 
 discharge. Outburst floods can have kinematic waves that are introduced to
  a flood via hydraulic ponding. A partitioning of flow regimes occurs due 
 to time-transgressive changes in channel cross-section\; specifically betw
 een inner channel and overbank regions. Furthermore\, net erosion along a 
 reach can be related to hydraulic persistence above a marker value and net
  deposition can be related to a ‘time to peak’ value. These findings s
 hed light on the diversity and complexity of the Quaternary record of outb
 urst floods\, provoke consideration of the requirements for modern hazard 
 management strategies and quantify the controls on rapid landscape change 
 due to outburst floods.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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