Calculation of drainage divides beneath the Svartisen ice-cap using GIS hydrologic tools

Abstract

The Svartisen Hydropower Scheme is Norway's most recent hydropower development. Most of the runoff from West Svartisen (221 km², Fig. 1) is delivered to the power station via 60 intakes around the western and eastern ice-caps, including one subglacial intake located beneath the Engabreen outlet glacier. Estimates of water input to each intake are important for management of the power station. Average water inputs are obtained by integrating area-specific runoff over the intake catchment area. Previous calculations of the positions of catchment divides on Svartisen have been based upon ice surface topography alone and are thus a mapping of ice divides. However, meltwater flow along the glacier bed is driven by a gradient in hydraulic head, which is dependent on bed topography as well as ice surface topography. Calculations on other glaciers (Bjornsson 1988, Kennett 1990) show that the positions of water divides can differ significantly from ice divides.