Water Quality and Sediment Behaviour of the Future: Predictions for the
21st Century (Proceedings of Symposium HS2005 at IUGG2007, Perugia, July
2007). IAHS Publ. 314, 2007, 45-56
Modelling
discharge, water chemistry and sediment load from a subarctic river basin: the
Tanana River, Alaska
KAZUHISA A. CHIKITA1, TOMOYUKI
WADA1, ISAO KUDO2, DAISAKU KIDO1, YU-ICHI NARITA1 & YONGWON KIM3
1 Laboratory of Physical Hydrology, Faculty of
Science, Hokkaido University, Sapporo 060-0810, Japan
chikita@mail.sci.hokudai.ac.jp
2 Faculty of Fisheries Sciences, Hokkaido
University, Hakodate 041-8611, Japan
3 International Arctic Research Center, the
University of Alaska, Fairbanks, Alaska 99775-7340, USA
Abstract With reference to elevation effects on air temperature and rainfall, the time series of discharge,
suspended sediment concentration (SSC) and SiO2 in the Tanana River,
Alaska, are simulated by a conceptual model, the tank model. The
simulations are reasonable (correlation coefficient r = 0.684 to 0.953) for all the time
series obtained in the glacier-melt periods of 2002, 2004 and 2005. The smog
from large forest fires in the summers of 2004 and 2005 sporadically covered
the glacierized regions in the river basin, which were defined
by field observation and using satellite imagery. The correlation for the discharge series was
relatively low in or around the smog-covered periods. This is caused by the
overestimation of calculated glacier-melt discharge. The runoff analyses
revealed that, in spite of the 5.6% glacierized area, the glacier-melt discharge
comprises 35.2 to 54.2% of the river
discharge. The simulations of the SSC and SiO2 series suggest that
the suspended sediment originates mostly from glacierized regions, and SiO2
mainly from the mineral layer in the permafrost regions.
Key words forest fires; glacier; permafrost; sediment
load; Tanana River; tank model