484 HYDROLOGY
JFMAMJ JASONDJFMAMJ JASONDJFMAMJ JASOND
1963 1964 1965UBC Watershed ModelReconstitution of Seasonal Snowpacks (1963–1965)Goldstream River Basin2500’4500’6500’SNOWPACK WATER EQUIVALENT-INCHES123456789102030405060708090(^100) LEGEND
MOUNT ABBOT
GOLDSTREAM UPPER
FIDELITY MOUNTAIN
GLACIER
REVELSTONE
No 98 EL 6500 FEET
No 128 EL 6300 FEET
No 129 EL 6150 FEET
No 11 EL 4100 FEET
No 15 EL 1850 FEET
FIGURE 10 Comparison of computed snowpacks and snowcourse data.
One of the fi rst steps in calibrating a watershed is to study
the orographic precipitation gradients. The model algorithm
describing the variation of precipitation with elevation and
temperature is calibrated by comparing calculated snow-
packs at various time intervals with the snowcourse mea-
surements, as shown in Figure 10. The complete comparison
during accumulation and depletion of snowpacks requires
estimation of precipitation by elevation, the form of precipi-
tation, rain or snow, and the snowmelt occurring at various
times. The temperature lapse rate is therefore an important
ingredient in this part of the analysis, infl uencing both melt
rates and orographic gradients.
Reconstitution of outfl ow hydrographs is the next stage
of model calibration and two examples which have been
presented in detail previously, Quick and Pipes 48,50 will be
briefl y outlined. The Jordan River example, Figure 11, illus-
trates the considerable improvement which is achieved by
using temperature based snowmelt equations which account for
additional radiation melt and condensation melt components.
For comparison, the melt calculated from only the mean air
temperature is plotted. In periods of extreme snowmelt, the
melt rate can be approximately double the rate that might
be estimated from mean temperature alone. For the example
given, plots of temperature and precipitation at a base station
are presented for comparison with the outfl ow hydrograph.
In another example illustrated in Figure 12 for the
Spillimacheen River, an earlier paper, Quick and Pipes (1977)
discussed and compared the accuracy attainable using different
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