The Sagavanirktok River is the second-largest river on the North Slope of Alaska (drainage basin area = 14,364 km², 5,500 mi²; length = 267 km, 165 mi). Maximum discharge recorded during the spring breakup was 2,320 m³/sec (82,000 cfs); flow ceases during the winter freeze. The river flows through terrain underlain by continuous permafrost ranging up to 300 m (1,000 ft) thick. It is a coarse-gravel, braided river that is degradational through most of its length, becoming aggradational on the last 20 km (12 mi) of delta plain. The active channels contain longitudinal bar complexes and large transverse bars, including T-bars at the ends of chutes incised into the inactive fluvial plain. Chutes form during spring breakup owing to blockage of he river by ice from icings (aufeis), or by ice drives that jam and direct the river laterally onto the inactive fluvial plain.

Relict fluvial systems also exist as terraces elevated 10-30 m (30-100 ft) above the active river. This terrain contains wind-aligned lakes developed in the permafrost active layer. Next to the terrace scarp is an eolian levee composed of silt and fine sand derived from the active river.

Numerous small, high-gradient alluvial fans have formed along hills adjacent to the lower alluvial plain. Coarse gravel is transported downfan to the Sagavanirktok River primarily by debris flows that have prominent sieve lobes at the ends of U-shaped channels. The flows are fed by spring runoff, melting of ground ice during the thaw season, and by ground-water-fed springs (small icings).

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