Suspended sediment and bedload transport rates for the Tanana River near Fairbanks, Alaska, can be related to water discharge, and annual sediment loads can be computed using these relations. For a site near Fairbanks, the average annual (1974-79) load is 24 million metric tons of suspended sediment and 321,000 metric tons of bedload. Upstream, near North Pole, the average annual load is 20.7 million metric tons of suspended sediment and 298 ,000 metric tons of bedload. For both sites bedload is usually 1 to 1.5 percent of suspended sediment load. Particle size distribution of suspended sediment is similar at Fairbanks and North Pole. Median particle size is generally in the silt range, but at some low-water discharges, it is in the very fine sand range. Median particle size of bedload near North Pole is generally in the gravel range, but at some low transport rates, it is in the medium sand range. In 1977 median bedload particle size was comparable at the two sites, but in 1978 the median size was markedly smaller at Fairbanks. In 1979, generally coarser material was transported at both sites, but the decrease in bedload particle size was even greater between the sites. At both sites and at all water discharge and sediment transport rates, suspended load particles are significantly smaller than bedload particles. At North Pole in 1979, median bed material particle size was in the course gravel range; at Fairbanks it was in the medium gravel range in the main channel but in the fine sand range in the overflow part of the channel. (USGS)
