Runoff Modeling for the Tom’ River Basin in a Changing Climate

A methodology for assessing hydrological consequences of climate change in the Tom’ River basin was implemented using the results of calculations with an ensemble of CMIP5 global climate models in combination with the ECOMAG river runoff formation model. The calibration and verification of the model for the Tom’ River basin was carried out using stream gauging station and EWEMBI reanalysis data for the periods 1989–2002 and 2003–2016. As initial climatic data, the authors used data from four main ISI-MIP2 models: GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, and MIROC-ESM-CHEM. Under the considered scenarios, the runoff volume is expected to increase by 10–20% on average by the end of the 21st century relative to the baseline historical period. Under the RCP 8.5 scenario, the hydrograph will be transformed: the peak discharges will increase, the onset of a spring flood will be shifted to earlier dates, and its duration will be reduced. Statistical parameters of the simulated series of maximum discharges (normals, coefficients of variation, discharges of a 1% probability) for the period of the climate forecast have also been estimated. An increase in maximum discharges by 10% is possible in the second half of the 21st century.