Forecasting changes in river water resources of Russian Federation based on CMIP5 runoff data

Abstract

The article is devoted to the analysis of river runoff data provided by the latest generation of the Coupled Atmosphere-Ocean General Circulation Models (AOGCMs) in the framework of the CMIP5 project. The main aim of this research is to forecast the probable changes in river water resources of the main rivers of the Russian Federation. At the first stage of investigation, a comprehensive analysis of the river runoff computational models and the quality of the initial AOGCMs information were carried out. This analysis was performed in several steps. First, the average long-term model river runoff for the base period of 1981–2000 was compared with the average long-term values of the observed discharge for the seven largest rivers of the Russian Federation (Volga, Pechora, Northern Dvina, Ob, Lena, Yenisei and Amur). In addition, the spatial distribution of the river runoff throughout the territory of Russia provided by the AOGCMs was analyzed. Then, the adequacy (negative or unrealistic runoff values) of the simulated future runoff changes for each of the forecast scenarios was checked. If any of the verification tests revealed incorrect model data, the model was excluded from further research. As a result, 24 AOGCMs were selected. At the second stage of research, a model ensemble was formed based on the 24 selected models for the implementation of forecasting estimates. The forecasting estimates were carried out for two forecast periods (2021–2040 and 2041–2060) in relation to the 1981–2000 period. Calculations were performed for two (RCP4.5 and RCP8.5) forecast scenarios. As a result, future changes in river water resources of the 34 largest rivers of the Russian Federation were obtained and analyzed; additionally, maps of future changes in annual runoff depth over the territory of Russia were constructed.