Flood risk in Siberia increased in recent years. This is most often associated with two main reasons: global climate change, and the increase in economic development in territories at risk of flooding and resulting human impacts on river basins. We tried to bring new data and results on this topic. The objective of this paper is to assess the change in the hydrological regime under climatic changes and the dynamics of flood recurrence on the river basins of southern East Siberia in the latter half of the 20th and the beginning of the 21st century. We used information on run-off and water levels obtained from hydrological stations of the Irkutsk and Ulan-Ude Administration for Hydrometeorology and Environmental Monitoring.
The annual and monthly mean run-off data series were subjected to statistical analysis. Linear trends and their significance were evaluated in general for the identical period from 1961 to 2006 at 37 gauging stations. Flood recurrence in the Angara and Lena river basins was calculated for two periods – before the expressed climatic changes (1960–1979) and for the expressed climatic changes (1980–2005). In general, the value of the annual run-off was unchanged. The intra-annual redistribution of run-off occurs, showing a reduction in the run-off from spring snowmelt and an increase in run-off for the autumn – winter low water period. Intra-annual run-off redistribution under climatic changes does not provoke an increase in extreme conditions. The analysis of flood recurrences showed no significant changes in the mean recurrence in basins. However, there was either a significant increase or decrease in the number of floods for some gauging stations. Remote sensing data were used to analyse the dynamics of human impact on such river basins. Copyright © 2013 John Wiley & Sons, Ltd.