Kobuk River - Surface Water and Hydrology

Surface Water and Hydrology

The Kobuk River is ice covered 6 months of the year and in general, late October to late May is a period of relatively low flow. Annually, the hydrograph reflects two flood peaks: the first is associated with spring break-up and the second, a lesser peak, is associated with late summer precipitation. As the snowpack begins to melt toward the end of May, flow in the Kobuk River increases with most of the runoff occurring during June. Flow during the summer (July through September) is dominated by variable precipitation events.

Most of the major tributaries of the Kobuk River flow from the north, draining the mountains in the southern Brooks Range. From east to west, these include the Reed River, Beaver Creek, Mauneluk River, Kogoluktuk River, Shungnak River, Ambler River, Akillik River, Tutuksuk River, Salmon River, and the Squirrel River. Within Kobuk Valley National Park, are the Kallarichuk, Kaliguricheark, and Adillik rivers. All of their headwaters are in the Baird Mountains. The major tributaries flowing north from the Waring Mountains are the Pah River, Pick River, and Niaktuvik Creek. The Pah River drains a lowland area of the basin. Most major tributaries draining high relief areas have higher unit runoff than tributaries draining the lower relief areas.

Walker Lake is at an altitude of 194 metres (636 ft) in the headwaters of the Kobuk River. Other surface water features within the basin include Lake Selby, Nutuvukti Lake, and Norutak Lake. Additionally, numerous small lakes and ponds occur in the lowlands along the river, some formed as detached oxbows of the meandering river and others formed where permafrost has melted and caused depressions.

Flow records are available from USGS monitoring stations at Ambler and Kiana. Average annual flow for the Kobuk River at Ambler has ranged from 5,839 cubic feet per second (165.3 m3/s) to 14,890 cubic feet per second (422 m3/s) over the period of record 1966-78, with peak discharge ranging from 30,000 cubic feet per second (850 m3/s) to 95,000 cubic feet per second (2,700 m3/s). Near Kiana, average annual flow has ranged from 10,020 cubic feet per second (284 m3/s) to 24,960 cubic feet per second (707 m3/s) for the period 1977-99 with peaks of 45,000 cubic feet per second (1,300 m3/s) to 161,000 cubic feet per second (4,600 m3/s). Peak flows can result from large volumes of water released when ice jams fail. Flow records are also available for Dahl Creek, a tributary of the Kobuk River with a confluence near the town of Kobuk.