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Dr Alison Banwell, BSc, PhD

Institute Associate

Alison studied Geology and Physical Geography at the University of Edinburgh from 2004 – 2008. Already a keen climber and mountaineer, it was there that she developed a fascination for glaciers. In 2008, Alison received a NERC Doctoral Training Grant to fund her PhD at the Scott Polar Research Institute, University of Cambridge. Fieldwork has taken her to Greenland and under the ice in Svalbard.

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PhD Research

Supervisors: Ian Willis, Neil Arnold & Andreas Ahlstrom (Geological Survey of Denmark & Greenland)

My PhD research focussed on the hydrology of the ~2,300km2 Paakitsoq region of West Greenland. I developed a distributed, physically-based numerical model of melt and water movement through the surface, englacial, and subglacial components of the ice sheet hydrological system. Ultimately, the model enables the calculation of subglacial water pressures in response to the main controlling variables of subglacial drainage system structure and surface meltwater inputs. This is important following recent studies indicating that surface meltwater is reaching the bed of the Greenland Ice Sheet and modulating glacier sliding rates at the ice sheet margin. However, the hydrological characteristics of this drainage system and the degree to which variations in subglacial water pressure enhance or impede ice flow remain uncertain.

The supraglacial melt model component includes: i) an energy-balance model calculating spatial and temporal variations in melt rates across snow and ice, and ii) a subsurface model routing water vertically down through unsaturated snow, accounting for conduction and re-freezing within the snowpack. The supraglacial routing model routes water: i) in a saturated layer at the base of the snowpack, or ii) across ice, towards lakes / moulins. Once a lake is full, input discharge is routed to the lake outlet using the DEM topography. Water flows in a series of 'cascades' from its initial source cell through a series of full lakes, until it either reaches a lake which is yet to overflow, or reaches the edge of the DEM domain. Meltwater can be routed englacially from the surface to the ice / bed interface via moulins or supraglacial lake drainage events following hydrofracture. Discharge and hydraulic head within subglacial conduits are modelled using an adaptation of a component (EXTRAN) of the US EPA Storm Water Management Model (SWMM), modified to allow for enlargement and closure of ice walled conduits.

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