APPLICATION OF INDEXED SNOWMELT ALGORITHMS IN A NORTHERN WETLAND REGIME

Applications of snowmelt models in Canada's north have been limited la rgely to energy balance models concentrating on micro scale studies or macroscale applications. The latter rely solely on basin-wide, optimi zed parameters for hydrological simulation and often neglect some of t he major physical processes controlling melt production. Although phys ically realistic models can be implemented at the micrometeorological scale, the data requirements are often too numerous to make these type s of models practical to apply at the meso- or macroscales. On the oth er hand, the standard lumped model approach often oversimplifies the p hysical processes and fails to reveal subtle differences between land cover types and their specific response to meteorological inputs. This paper focuses on the use of indexed snowmelt algorithms derived for i ndividual land cover component characteristics of the wetland dominate d region of the lower Liard River Valley, NWT, Canada. These algorithm s use an hourly temperature index and a combination radiation-temperat ure index approach to estimate snowmelt within the different land cove r types. The algorithms developed are incorporated into a fully distri buted hydrological model (SPL7) that uses the grouped response unit (G RU) method for basin discretization. Snowmelt indices are estimated fo r both approaches using snow cover depletion data obtained during an e xtensive field campaign. The indices are then validated using historic al data from complementary studies. Results show that the radiation-te mperature algorithm provided slightly improved calibration results; ho wever, both algorithms validated equally well. (C) 1998 John Wiley & S ons, Ltd.