The aim of this thesis is to evaluate the meltwater contribution from the western margin of the Greenland ice sheet by a detailed analysis of a large regional hydrological basin.

An assessment of the regional climatology is obtained using data from previous investigations combined with data collected during the current project. The specific mass-balance of Amitsuloq ice cap in the centre of the investigated region is established for the period 1982-1990 and a correlation coefficient of R^2=0.93 found between the specific summer-balance and the annual discharge of the Tasersiaq basin. The change in the equilibrium line altitude from the coast to the ice-sheet margin in West Greenland is established as 3.4 m pr. km. The 3 m air-temperature lapse rate on the ice sheet shows strong variations from month to month, varying between 0.4 and 1.1 C/100m.

Remotely sensed data sets are retrieved from aircraft and satellites, yielding a detailed elevation model, a bedrock elevation model and temporally and spatially distributed albedo data. The AVHRR Polar Pathfinder (APP) albedo data is validated with AWS albedo measurements on the ice-sheet margin showing that the APP albedo is on average 0.042 less than the locally measured albedo with a root-mean-square error of 0.07. The narrow-to-broadband conversion used in the APP albedo generation algorithm was checked by comparing to field measurements and found to perform equally well over the entire range of measured broadband albedos from 0.09 to 0.63.

Observation and modelling of the surface energy-balance on the ice-sheet margin indicate that the incoming longwave radiation is the largest energy-source for melt, followed by the net shortwave radiation and then the sensible heat flux. The variation in the absorbed shortwave radiation due to changes in the albedo is found to be most important in explaining variations in the melt rate. The regional ablation is calculated with a distributed energy-balance model utilizing AVHRR-derived albedo maps available for 1997. The standard deviation of the modelled ablation is found to be roughly 10% of the mean ablation for a given altitude.

Delineation of the hydrological catchment within the ice sheet is obtained by combining all available elevation data for the ice-sheet surface and bedrock to establish the water pressure potential at the bedrock. The areal extent of the ice-sheet part of the Tasersiaq basin is found to vary in a non-linear way with rising water pressure potential.