Hydrological changes across Northern Eurasia: contemporary status and future projections

Evidence pointing to significant change in the hydrological regime over the North Eurasian region were analyzed. Understanding alterations due to both global climate change and local anthropogenic influences are important to explore potential signals of global climate change and to assess their feedbacks to hydrological systems and the global climate, and to their impacts upon humans. We analyzed changes in annual, monthly and daily extreme discharge for river basins with minimal human impact along with total river inflow to the Arctic Ocean from the largest watersheds and sea basins. The effect of human impacts was estimated through water use data collected at the State Hydrological Institute (SHI), Russia. The role of reservoir regulation in discharge variability was analyzed with a newly developed Hydrograph Transformation Model (HTM). The model is based on the unit hydrograph approach and transforms daily hydrographs sequentially from upstream to downstream to reduce the effects of reservoir regulation. To explore potential future patterns of change in the hydrology of Northern Eurasia we used projections of climate changes simulated by two coupled atmosphere-ocean general circulation models (AOGCMs) to drive our hydrological models. Future simulations from the UNH Water Balance and Water Transport Models (WBM/WTM) which incorporate irrigation and reservoir effects were analyzed along with results from the SHI and UNH permafrost water balance models with improved frozen ground schemes. All models demonstrated a general tendency toward increases in river runoff although the changes across Northern Eurasia were not spatially uniform.