Field-scale water balance closure in seasonally frozen conditions
File(s)
Published version
Author(s)
Pan, X
Helgason, W
Ireson, A
Wheater, H
Type
Journal Article
Abstract
Hydrological water balance closure is a simple concept, yet in practice it is uncommon to measure every significant term independently in the field. Here we demonstrate the degree to which the field-scale water balance can be closed using only routine field observations in a seasonally frozen prairie pasture field site in Saskatchewan, Canada. Arrays of snow and soil moisture measurements were combined with a precipitation gauge and flux tower evapotranspiration estimates. We consider three hydrologically distinct periods: the snow accumulation period over the winter, the snowmelt period in spring, and the summer growing season. In each period, we attempt to quantify the residual between net precipitation (precipitation minus evaporation) and the change in field-scale storage (snow and soil moisture), while accounting for measurement uncertainties. When the residual is negligible, a simple 1-D water balance with no net drainage is adequate. When the residual is non-negligible, we must find additional processes to explain the result. We identify the hydrological fluxes which confound the 1-D water balance assumptions during different periods of the year, notably blowing snow and frozen soil moisture redistribution during the snow accumulation period, and snowmelt runoff and soil drainage during the melt period. Challenges associated with quantifying these processes, as well as uncertainties in the measurable quantities, caution against the common use of water balance residuals to estimate fluxes and constrain models in such a complex environment.
Date Issued
2017-11-01
Date Acceptance
2017-07-25
Citation
Hydrology and Earth System Sciences, 2017, 21 (11), pp.5401-5413
ISSN
1027-5606
Start Page
5401
End Page
5413
Journal / Book Title
Hydrology and Earth System Sciences
Volume
21
Issue
11
Copyright Statement
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License (https://creativecommons.org/licenses/by/3.0/)
the Creative Commons Attribution 3.0 License (https://creativecommons.org/licenses/by/3.0/)
Subjects
0406 Physical Geography And Environmental Geoscience
0905 Civil Engineering
0907 Environmental Engineering
Environmental Engineering
Publication Status
Published
Date Publish Online
2017-11-01