Freshwater input to the Ob' estuary and modern hydrological regime of the Northern part of Western Siberia

We focus on the freshwater input to the Ob' estuary and the Kara sea from the rivers in the Northern part of the Western Siberia (the rivers Poluy, Nadym, Pur and Taz - PNPT), as well as the the Ob' itself. While the intrazonal Ob' river with its huge watershed reflects influence of various environmental conditions, the PNPT rivers are characterised by more homogeneous natural conditions and this makes them a reliable and important indicator of the climate variability of the Arctic part of the Western Siberia. We assess the modern hydrological regime of the rivers flowing to the Ob' estuary and compare it with the historical observations. First we present seasonal and interannual variability and analyse temporal and spatial tendencies. We then quantify the contribution of various sources to the total runoff and analyse its particularities for each river as a function of climate changes and human impact. Volume of meltwater passed during spring flood is compared with estimates of snow from in situ, reanalysis and passive microwave satellite data. Finally, we estimate the role of wetlands in the transformation of the river runoff into the Ob' bay by applying satellite radar altimetry to estimate the variations of storage capacity of the wetlands.