Climate Change Impact On Water Balance Components In Arctic River Basins

Climate change impact on the water balance components (including river runoff, evapotranspiration and precipitation) of five Arctic river basins (the Northern Dvina, Taz, Lena, Indigirka, and MacKenzie), located in different natural conditions, was investigated using a physically-based land surface model SWAP and meteorological projections simulated at half-degree spatial resolution by five Global Climate Models (GCM) for four Representative Concentration Pathways (RCP) scenarios from 2005 to 2100. After the SWAP model calibration and validation, 20 projections of changes in climatic values of the water balance components were obtained for each river basin. The projected changes in climatic river runoff were analyzed with climatic precipitation and evapotranspiration changes. On average, all rivers’ water balance components will increase by the end of the 21st century: precipitation by 12-30%, runoff by 10–30%, and evapotranspiration by 6-47% depending on the river basin. The partitioning of increment in precipitation between runoff and evapotranspiration differs for the selected river basins due to differences in their natural conditions. The Northern Dvina and Taz river runoff will experience the most negligible impact of climate change under the RCP scenarios. This impact will increase towards eastern Siberia and reach a maximum in the Indigirka basin. Analysis of the obtained hydrological projections made it possible to estimate their uncertainties by applying different GCMs and RCP scenarios. On average, the contribution of GCMs to the uncertainty of hydrological projections is nearly twice more significant than the contribution of scenarios in 2006–2036 and decreases over time to 1.1-1.2 in 2068–2099.