River Water Temperature in Relation to Local Air Temperature in the Mackenzie and Yukon Basins

Daqing Yang,Amber Peterson

doi:10.14430/arctic4627

Abstract

Water temperature has an important impact on many aspects of basin hydrology and ecology. In the northern regions, investigation of river thermal regimes and their changes over space and time is a challenge because of data limitations. This study determines the water temperature regimes at several locations within the Yukon and Mackenzie River basins and examines their relationship with air temperature. The Yukon and Mackenzie Rivers have distinct water temperature dynamics. They remain near zero from freeze-up in the fall to ice breakup in the spring and reach their peak temperature during mid-summer. For the locations examined, peak mean monthly water temperatures ranged from 9˚ to 15˚C, and mean July air temperatures ranged from 13˚ to 16˚C. The lags between water and air temperatures ranged from 1 to 40 days. The largest lag was found at the Great Bear River monitoring location, since water temperature at this site is strongly influenced by the heat storage of Great Bear Lake. Tests of three models, linear regression, logical regression (s-shape), and the physically based air2stream model, show that the air2stream model provided the best results, followed by logical regression. Linear regression gave the poorest result. Model estimates of water temperature from air temperature were slightly improved by the inclusion of discharge data. The water temperature sampling regimes had a considerable effect on model performance; long-term data provide a more robust test of a model. Comparisons of mean monthly water temperatures suggest significant spatial variability and some inconsistency between upstream and downstream sites that is due mainly to differences in data collection schemes. This study strongly demonstrates the need to improve water temperature monitoring in the northern regions.

Highlights

River thermal conditions influence biological and ecological processes within the basin and near the coastal regions
Water temperature data were collected at the Klondike River monitoring site during 2010 – 12
Water temperature data are lacking across the Mackenzie and Yukon River basins, longterm records with high temporal frequency

Summary

Introduction

River thermal conditions influence biological and ecological processes within the basin and near the coastal regions. As a result of climate change and human impacts, stream temperatures have warmed by several degrees over many regions, including the United States, Australia, and Russia (Webb and Nobilis, 1995; Liu et al, 2005; van Vliet et al, 2011). In high-latitude regions, water temperature and discharge significantly affect the freeze-up and breakup processes, the thickness of river ice, and thermal erosion along the riverbanks. Costard et al (2003) found water temperature and discharge to be the main factors in thermal erosion of the frozen riverbanks in the Lena basin. Liu et al (2005) and Yang et al (2005), using the long-term water temperature records over the Lena basin, discovered significant trends in river thermal conditions as results of regional climate warming and human impacts, reservoir regulation. In high-latitude regions, water temperature and discharge significantly affect the freeze-up and breakup processes, the thickness of river ice, and thermal erosion along the riverbanks. Marsh and Prowse (1987) examined the influence of stream heat on overlying ice cover of the Liard River and reported large spatial and temporal variations in water temperature and heat flux. Costard et al (2003) found water temperature and discharge to be the main factors in thermal erosion of the frozen riverbanks in the Lena basin. Liu et al (2005) and Yang et al (2005), using the long-term water temperature records over the Lena basin, discovered significant trends in river thermal conditions as results of regional climate warming and human impacts, reservoir regulation. Lammers et al (2007) analyzed water temperature data and calculated heat energy for the large Siberian rivers and reported a consistent increase in the decadal maximum temperature for the basins in the European part of Russia

Methods

Results

Conclusion