Changes in river runoff in Latvia at the end of the 21st century

This study deals with future climate change impacts on the runoff of five Latvian river basins at the end of this century. Climate data series have been provided by the Faculty of Physics and Mathematics of the University of Latvia where the regional climate model Rossby Centre Atmosphere Ocean was selected for further statistical downscaling. Changes in hydrometeorological data have been analysed based upon one control run (period 1961 1990) and two future scenario A2 and B2 runs (2071 2100). The conceptual rainfall-runoff model, the latest version of METQ2007BDOPT, was used for simulation of hydrological processes in particular river basins. Simulation results revealed that in comparison to the control period, major differences in hydrometeorological parameters in future were observed according to A2 scenario, where long-term mean air temperature will grow by 4 degrees and precipitation by 12%, while mean annual river flow will decrease by 19%. Both scenarios demonstrate changes in seasonal runoff patterns where the major part of river runoff will be generated in winter, followed by spring, autumn and summer. The river hydrograph is going to take a different shape, where the maximum river discharges will occur in winter instead of spring.