Percolation of meltwater in the snowpack and subsequent refreezing has animportant retardation effect on runoff and therefore cannot be neglectedwhen studying the surface mass balance of the Greenland ice sheet.In this study we make a detailed comparison of three different treatments toaccount for meltwater refreezing in large-scale parameterisations used formodelling the Greenland ice sheet. These three treatments respectively followReeh (1989), Oerlemans (1991), and Pfeffer et al (1991), and are characterizedby varying degrees of complexity and physical basis. We discuss the roleof meltwater retention in the light of the overall mass-balance of theGreenland ice sheet and its sensitivity to climatic change. Wemake use of new high-resolution datsets for surface elevation andaccumulation rate which take into account recent data sources. The degree-daymodel to calculate the snow- and ice melt has also been refined and recalibratedby comparing mass-balance characteristics with available observations on aregional basis. We will also present a new calculation of the different zones(facies) which characterize the accumulation area of the Greenland ice sheet.