Changes in hydrological regime in High Arctic non-glaciated catchment in 1979–2020 using a multimodel approach

Abstract

Assessing hydrological consequences of climate change at the catchment scale is recently among key problems in hydrology. This study focuses on the estimation of changes in the hydrological regime in the Fuglebekken catchment in SW Spitsbergen (Svalbard). For this purpose, 50 rainfall-runoff models were calibrated using available hydrometeorological observations. The models were validated based on archival flow and SWE observations, and proxy data from time-lapse cameras. Six models (FLEX-IS, GSM-SOCONT, PRMS, HBV, Nordic HBV, and GR4J) with the best performance were applied to reconstruct the past hydrological conditions and analyse the trends in flow regime in the period 1979–2020. Statistically significant changes at 0.05 level in the flow regime indicators were detected, including the number of days with the active flow during the calendar year (10.8 d per decade), during the mid-May‒November period (9.8 d per decade), the date of the first day with the flow (−4.7 d per decade), and the last day with the flow during mid-May‒November (8.4 d per decade). A statistically significant increase in runoff was estimated for two periods from mid-May to the end of June and the second part of August till mid-November. The changes in the first period result from increases in air temperature and earlier snowmelt-driven floods. An estimated runoff increase in the second period corresponds to large increases in rainfall. The increase in air temperature, earlier disappearance of snow, and decrease in precipitation in July and the first part of August result in runoff reduction. The presented results show that the Fuglebekken ‘catchment's hydrological regime has already changed. The magnitude of the changes is larger compared to catchments located in lower latitudes.

Keywords

• Hydrological regime
• Climate change
• Svalbard
• High Arctic catchment hydrology
• Multimodel approach