Author(s)

Kazuhisa A. Chikita, Tomoyuki Wada, Isao Kudo, Yongwon Kim

Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Japan.
Faculty of Science, Hokkaido University, Sapporo, Japan.
International Arctic Research Center, University of Alaska, Fairbanks, USA.

The covered-ice breakup in subarctic to arctic rivers in the early snowmelt season often gives any damage to instruments monitoring physical and chemical factors of water. The serious condition has brought few time series data during the snowmelt runoff except the river stage or discharge. In this study, the contribution of snowmelt runoff to the discharge and sediment load is quantified by monitoring water turbidity and temperature at the lowest gauging station of U. S. Geological Survey in the Yukon River, Alaska, for more than 3 years (June 2006 to September 2009). The turbidity was recorded by a self-recording turbidimeter with a sensor of infrared-ray back-scattering type, of which the window is cleaned by a wiper just before a measurement. The turbidity time series, coupled with frequent river water sampling at mid-channel, produce time series of suspended sediment (SS) concentration, particulate organic carbon (POC) concentration and particulate organic nitrogen (PON) concentration (mg?L^–1) by using the high correlation (R² = 0.747 to 0.790; ^P < 0.001) between the turbidity (ppm) and the SS, POC and PON concentrations. As a result, the three-year time series (5 September 2006 to 4 September 2009) indicated that the snowmelt runoff, continuing about 40 days (late April or early May to early June), occupies 14.1% - 24.8% of the annual discharge (1.94 × 10¹¹ to 2.01 × 10¹¹ m³), 8.7% - 22.5% of the annual sediment load (3.94 × 10⁷ to 5.08 × 10⁷ ton), 11.6% - 23.7% of the annual POC flux (4.05 × 10⁵ to 4.77 × 10⁵ ton), and 10.3% - 24.5% of the annual PON flux (2.80 × 10⁴ to 3.44 × 10⁴ ton). In the snowmelt season, the peak suspended sediment concentration preceded the peak discharge by a few days. This probably results from the fluvial sediment erosion in the river channels.

Yukon River; Suspended Sediment Concentration; POC; PON; Sediment Load; Snowmelt Runoff; Glacier-Melt Runoff

Chikita, K. , Wada, T. , Kudo, I. and Kim, Y. (2012) The Intra-Annual Variability of Discharge, Sediment Load and Chemical Flux from the Monitoring: The Yukon River, Alaska. Journal of Water Resource and Protection, 4, 173-179. doi: 10.4236/jwarp.2012.44020.