Temporal sequencing of annual spring runoff in major Arctic-draining rivers

For northern Arctic-draining rivers, the spring freshet is the dominant annual discharge event producing the majority of freshwater inflow to the Arctic Ocean. Freshwater storage and circulation within the ocean are affected by seasonality of the spring freshet, which can also have impacts on the Arctic cryosphere, biota and linkages to global climate through thermohaline circulation. Considering the potential consequences, it is important to establish the spatial and temporal variability of spring freshets of Arctic rivers. To accomplish this objective, historic flow data from selected hydrometric stations within four major watershed basins draining to the Arctic Ocean have been analyzed to extract flow metrics of the annual spring freshet. The drainage basins studied provide the greatest freshwater contribution to the Arctic Ocean: the Mackenzie (North America), Lena (Eurasia), Yenisey (Eurasia) and Ob (Eurasia) river basins. Occurrence date of peak flows, length of freshet, volume of freshet, and nominal freshet shape have been extracted for available years of record from hydrometric stations located at the outlets of the four rivers, as well as a subset of stations gauged on tributary systems. Results show the temporal sequencing of the four outlet stations located at the Mackenzie River at Arctic Red River, Lena River at Kusur, Yenisey River at Igarka, and Ob River at Salehard, and identify the major controls of extreme high and low flow years. Specifically, links are made with climatic drivers and atmospheric circulation patterns. Special focus is placed on the Mackenzie River tributary stations located within the Climatic Redistribution of Canada's Water Resources (CROCWR) region, as part of an integrated study of which a partial objective is to determine relationships of spring freshet variability with climatic driving forces and synoptic climatological patterns.