Distribution of River Water and Suspended Sediment Loads in the Deltas of Rivers in the Basins of The Laptev and East-Siberian Seas

Abstract

The article presents estimates of the annual and seasonal distribution of river water and suspended sediment load and their variability in complicated fork river deltas of the Laptev and East-Siberian Seas. The estimates are based on the methodology, which includes a complex of developed or improved methods for hydraulic-morphometric parameterization of channels, hydraulic calculations and physical and numerical modeling. A particular emphasis is given to rivers Lena and Kolyma deltas that belong to different types according hydrologic regime. In the Lena delta only its lower part is influenced by the sea. In the Kolyma delta the whole of the water area including the head of the delta experiences the influence of the sea. The main factor affecting water runoff and sediments distribution in the Lena delta branches is river runoff. For the Kolyma delta under the conditions of steady water motion the water content ratios of the main arms remain quite stable at different combinations of water discharges in the river and background sea level. At large surge level rises there is a considerable redistribution of water discharges over the delta area, reverse currents are observed (negative discharge values). A comparative analysis of estimates of the water runoff distribution in the Kolyma delta obtained by different methods shows that hydraulic calculations are sufficient for most applied tasks. Further studies should be focused on developing methods to calculate sediment transport for assessing the distribution of pollutants in deltas and their export to the sea.