Keywords

modeling, aggregation, hrus, slope and aspect, snow melt

Start Date

1-7-2006 12:00 AM

Description

Reliable hydrological modeling at small to medium scales is very difficult. At these scale, models require incorporation of both detailed process understanding and inputs along with information gained from observations of basin-wide streamflow phenomenon; essentially a combination of deductive and inductive approaches. At Granger Creek, part of the Wolf Creek Research Basin in the mountains of the Yukon Territory, Canada, sparse and shrub tundra cover the basin and soils are frozen at the time of snowmelt. Wind redistributes snow to north facing slopes and shrub tundra areas, while spring melt rates are much higher on south facing slopes due to increased incident solar radiation. Soil moisture and porosity are higher on north facing slopes and notably smaller on south facing slopes, reflecting cumulative differences in summer evaporation losses and the presence of permafrost on north slopes. Observations of streamflow show that peak flows are due to snowmelt, and that the timing of the peak is associated with the timing of snowmelt in the shrub-tundra vegetation zone, while the duration of the peak is associated with the duration of snowmelt on north facing slopes and high elevation zones. Despite small scale observations of rapid and early snowmelt on the south facing slopes, melt from these slopes occurs well before the spring hydrograph rise. To incorporate information from our recent advances in process understanding and in basin streamflow behavior, a ‘hydrological response’ landscape unit modeling approach is used including information on: slope, aspect, shrub canopy, snow water equivalent, soil structure and soil moisture in order to predict snow-cover depletion and runoff generation. The importance of landcover parameters to snow covered area depletion, water balance and streamflow is investigated by a sensitivity analysis on parameter values and spatial aggregation of response units by comparisons to not only streamflow, but also to snow cover depletion.

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Jul 1st, 12:00 AM

The Use of Inductive and Deductive Reasoning to Model Snowmelt Runoff from Northern Mountain Catchments

Reliable hydrological modeling at small to medium scales is very difficult. At these scale, models require incorporation of both detailed process understanding and inputs along with information gained from observations of basin-wide streamflow phenomenon; essentially a combination of deductive and inductive approaches. At Granger Creek, part of the Wolf Creek Research Basin in the mountains of the Yukon Territory, Canada, sparse and shrub tundra cover the basin and soils are frozen at the time of snowmelt. Wind redistributes snow to north facing slopes and shrub tundra areas, while spring melt rates are much higher on south facing slopes due to increased incident solar radiation. Soil moisture and porosity are higher on north facing slopes and notably smaller on south facing slopes, reflecting cumulative differences in summer evaporation losses and the presence of permafrost on north slopes. Observations of streamflow show that peak flows are due to snowmelt, and that the timing of the peak is associated with the timing of snowmelt in the shrub-tundra vegetation zone, while the duration of the peak is associated with the duration of snowmelt on north facing slopes and high elevation zones. Despite small scale observations of rapid and early snowmelt on the south facing slopes, melt from these slopes occurs well before the spring hydrograph rise. To incorporate information from our recent advances in process understanding and in basin streamflow behavior, a ‘hydrological response’ landscape unit modeling approach is used including information on: slope, aspect, shrub canopy, snow water equivalent, soil structure and soil moisture in order to predict snow-cover depletion and runoff generation. The importance of landcover parameters to snow covered area depletion, water balance and streamflow is investigated by a sensitivity analysis on parameter values and spatial aggregation of response units by comparisons to not only streamflow, but also to snow cover depletion.