Hydrology and runoff routing of glacierized drainage basins in the Kongsfjord area, northwest Svalbard

Abstract. Freshwater discharge from tidewater glaciers modulates fjord circulation and impacts fjord ecosystems. There can be significant delays between meltwater production at the glacier surface, and discharge into the fjord. Here, we present a hydrological analysis of the tidewater glaciers around Kongsfjorden, northwest of Svalbard, examining the pathways of glacier surface melt to the glacier fronts. To simulate discharge hydrographs at the outlets of the major drainage basins in the Kongsfjord area we use 1) a simple, heuristic routing model and 2) the physically-based model HydroFlow to route runoff derived from a coupled surface energy balance – snow model. Plume observations at one of the tidewater glacier outlets and measurements of proglacial discharge of a land-terminating glacier are used for model calibration. Our analysis suggests that the local subglacial topography diverts a substantial amount of water from the drainage area of the glacier Kongsbreen to the neighboring glacier Kronebreen, across the border of their surface catchments. This is supported by the relative sizes of the plumes observed at the respective glacier fronts. Runoff from the glaciers on the south side of the fjord is one order magnitude lower than runoff from the glaciers on the east and north sides of the fjord, reflecting differences in the size of the glaciers. We derive discharge hydrographs at all the major outlets of Kongsfjord basin, presenting here a detailed analysis of two of the glacierized basins. The average annual discharge period from the tidewater glaciers due to surface runoff was 105 ± 10 days. The largest discharge comes from Kronebreen, which is equivalent to around 40 % of the total freshwater flux to the fjord.