MASS-BALANCE AND CHANGES OF SURFACE SLOPE, CREVASSE AND FLOW PATTERN OF ERIKBREEN, NORTHERN SPITSBERGEN - AN APPLICATION OF A GEOGRAPHICAL INFORMATION-SYSTEM (GIS)

The polythermal valley glacier Erikbreen (79-degrees-40'N 12-degrees-30'E), northern Spitsbergen, was investigated in 1970 and 1990 using digital photogrammetry and digital elevation model (DEM) techniques. The bottom topography was derived from radio-echo soundings. Based on the DEM, mass balance and changes of surface slope, crevasse and flow pattern were evaluated, and internal ice deformation velocities were calculated. Calculations of the total mass balance show that Erikbreen has not been in equilibrium for the last 20 years. The average surface lowering was 0.38 m/a and the volume had decreased by 5% to 6% from 1970 to 1990 or on the average by 3.5 x 10(6) m3 a-1 water. The glacier surface subsided over the whole glacier area except in minor areas with northfacing slopes in the accumulation area. The surface slope and the crevasse pattern, however, did not change significantly during the 20-year-period, except in areas below 100 m a.s.l.