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Abstract

In northern Europe, the risks of transport infrastructure and dams are related to changes in volume and magnitude of spring floods happening to rivers. We analyzed step-changes in time series of the spring flood runoff and yearly maximum water discharges that happened on 12 rivers located in Greenland (Denmark), Iceland, Norway, Sweden, Finland and the Russian Federation. The selected rivers are unregulated, with hydrometric records at sites available for 25–160 years. The step (jump) changes were detected wherever in the time series of the volume of spring flood or yearly maximum water discharge collected at 36–45 % of the records. The step changes are detected in 60 % river catchments covered by forest, polar tundra or tundra mixed with glaciated areas. In Finland and northern Russia, most of the step changes date to the early 1980s or 1990s; the step changes the volume and/or magnitude of spring floods have increased on average: by 24 – 38 % of northern Russian rivers, and by 11 – 14 % of Finnish rivers. Our results show that reconsidering the hydrological risks of those transport infrastructure which are located in the northern Finland and Russia.