Annual suspended sediment load of the Yenisei river

Field studies, including high-frequency sampling for suspended sediment flux estimation, were conducted in 2014–2016 in the city of Igarka, at the outlet of the Yenisei River. During spring freshet of each year, multiple suspended sediment concentration (SSC) peaks were observed, irrelated to water discharge fluctuations. The form of hysteresis loops evidences the importance of input from local in-channel sediment sources, i.e. banks and bedforms, and scouring of bed material, deposited during winter, in observed sharp SSC peaks. On the falling stage of the freshet, longer peaks are related to sediment waves from major tributaries, notably the Nizhnyaya Tunguska River. Annual sediment load was calculated based on the daily water discharge and observed SSC data, using sediment rating curves and LOADEST models as two reference methods. Mean annual suspended sediment load of the Yenisei River in Igarka is estimated at 8.1 ± 0.5 mln t., which significantly exceeds previously published values for the 1970–2001 period, from 4.6 to 5.9 mln t. Cumulative sediment load for 2014–2016 totals 24.2 ± 2.1 mln t.