Modelling snow water equivalent and spring runoff in a boreal watershed, James Bay, Canada

• Published in: Hydrological processes Vol. 28; no. 25; pp. 5991 - 6005
• Main Authors: Oreiller, M, Nadeau, D. F, Minville, M, Rousseau, A. N
• Format: Journal Article
• Language: English
• Published: Chichester Wiley 15-12-2014; Blackwell Publishing Ltd; Wiley Subscription Services, Inc
• Subjects: blowing snow relocation; blowing snow sublimation; Computer simulation; Crocus; data collection; field measurements; forests; gamma radiation; gamma ray snow gauge; hydrological modelling; Hydrology; land cover; landscapes; Mathematical models; melting; mixed degree-day / energy balance snow module; Modelling; rain; Runoff; Snow; snowmelt; spring; stream flow; sublimation; Thermodynamic models; thermodynamics; Thresholds; watersheds; wind speed; Quebec; Canada, Quebec; ANW, Canada, Quebec, James Bay
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.10091

The hydrology of boreal regions is strongly influenced by seasonal snow accumulation and melt. In this study, we compare simulations of snow water equivalent (SWE) and streamflow by using the hydrological model HYDROTEL with two contrasting approaches for snow modelling: a mixed degree‐day/energy balance model (small number of inputs, but several calibration parameters needed) and the thermodynamic model CROCUS (large number of inputs, but no calibration parameter needed). The study site, in Northern Quebec, Canada was equipped with a ground‐based gamma ray sensor measuring the SWE continuously for 5 years in a small forest clearing. The first simulation of CROCUS showed a tendency to underestimate SWE, attributable to bias in the meteorological inputs. We found that it was appropriate to use a threshold of 2 °C to separate rain and snow. We also applied a correction to account for snowfall undercatch by the precipitation gauge. After these modifications to the input dataset, we noticed that CROCUS clearly overestimated the SWE, likely as a result of not including loss in SWE because of blowing snow sublimation and relocation. To correct this, we included into CROCUS a simple parameterisation effective after a certain wind speed threshold, after which the thermodynamic model performed much better than the traditional mixed degree‐day/energy balance model. HYDROTEL was then used to simulate streamflow with both snow models. With CROCUS, the main peak flow could be captured, but the second peak because of delayed snowmelt from forested areas could not be reproduced due to a lack of sub‐canopy radiation data to feed CROCUS. Despite the relative homogeneity of the boreal landscape, data inputs from each land cover type are needed to generate satisfying simulation of the spring runoff. Copyright © 2013 John Wiley & Sons, Ltd.