Canadian Forest Service Publications

Assessment of water budget for sixteen large drainage basins in Canada. 2014. Wang, S.; Huang, J.; Li, J.; Rivera, A.; McKenney, D.; Sheffield, J. Journal of Hydrology 512:1-15.

Year: 2014

Available from: Great Lakes Forestry Centre

Catalog ID: 34950

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1016/j.jhydrol.2014.02.058

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Abstract

This study represents the first attempt to examine the spatial and seasonal variations of the surface water budget by using state-of-the-art datasets for sixteen large Canadian drainage basins with a total area of 3.2 million km2. The datasets used include two precipitation grids produced using measurements and reanalysis models, land surface evapotranspiration and water surface evaporation estimated using the EALCO model, streamflow measured at hydrometric stations, and total water storage change derived from GRACE satellite observations. The monthly water imbalance resulted from these datasets varied from 7.0 mm month−1 to 21 mm month−1 among the studied basins, which was 30% on average of the corresponding monthly precipitation. The accumulated water budget imbalance over the 7 years of 2002–2008 varied from close to zero to ±10 mm month−1. The positive and negative imbalances among the sixteen basins were largely offset and the all-basin imbalance was very close to 0. The uncertainties in precipitation, streamflow, evapotranspiration and total water storage change all contributed to the water budget imbalance and their relative magnitudes were found to vary with basin and season. In most cases, precipitation showed the largest uncertainties, which had similar magnitudes to the water budget imbalances. While improvements are noted in comparison with previous water budget studies over the regions, the water imbalance obtained for some basins is quite large, suggesting that considerable improvements in both the observation networks and models are necessary before the water budget closure can be substantially improved over this region.

Plain Language Summary

Understanding Canada’s regional water budgets is essential in water resources management and environmental applications. A water budget is the summation of inputs, outputs, and net changes to a particular water resource system, i.e. drainage basin or watershed, over a fixed period. Climate change and anthropogenic disturbances can have significant impacts on the water cycle of a water resource system. Therefore a water budget is essential in determining the magnitude of these impacts and to evaluate possible mitigation actions. This paper proposes and evaluates methods to characterise the spatial and seasonal variations of the water budget for drainage basins across Canada by using satellite imagery, field measurements, and modelling outputs. This paper also tries to identify the uncertainties and knowledge gaps in the current understanding of the water budget. The results of this research could support the assessment of climate changes impacts on water resources; i.e. glacier shrinkage and snow cover decrease, by providing more accurate quantitative estimates of water budgets.

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