Glacier Meltwater Contributions and Glaciometeorological Regime of the Illecillewaet River Basin, British Columbia, Canada

Figures & data

Table 1. Glacier area statistics for the glacierized portions of the Illecillewaet Basin. The estimated mapping error in glacier area is 3%.

Size Range (km^2)	GlacierCount	GlacierCount (%)	Glacier Area(km^2)	GlacierArea (%)
0.00–0.99	63	80	16.6	30
1.00–2.99	11	14	18.7	33
3.00–4.99	4	5	14.8	26
5.00–5.94	1	1	5.9	11
Total	79		56.0

Fig. 1 Map of the Illecillewaet Basin with the Illecillewaet Glacier located to the northeast and the Greeley Hydrometric station located to the southwest (green dot). Glacier polygons from Tobias Bolch, UNBC and 20 m DEM from Parks Canada.

Table 2. Glacier area and elevation statistics for Illecillewaet Glacier and glaciers within the Illecillewaet River sub-basin (IRB), 2005.

Glaciers	Area (km^2)	Glacier cover in the IRB (%)	Elevations (m)
			Min.	Median	Max.
Illecillewaet	5.94	1.0	1993	2521	2911
Sub-basin	56.0	4.9	1592	2385	2942

Fig. 2 Percentage of glacierized area versus elevation for the Illecillewaet Glacier and in the Illecillewaet basin.

Fig. 3 Topographic contour map of the Illecillewaet Icefield study area, with an elevation contour interval of 50 m (100 m on the glaciers). The field instrumentation from summer 2009 is also indicated. AWS; automatic weathers station; RP: Rogers Pass; T and RH: temperature and relative humidity stations, respectively.

Fig. 4 Vertical profiles of Illecillewaet Glacier for winter (long dashed lines), summer (short dashed lines), and net mass balances (solid lines) for 2009 (black), 2010 (dark grey), and 2011 (light grey).

Table 3. Observed and modelled mass balance and glacier runoff, 2008 to 2011 (m w.e.) of Illecillewaet (Ille) Glacier and Illecillewaet River Basin (IRB). Uncertainty estimates are discussed in the text.

Season	2008–09	2009–10	2010–11	Average
Observations
Winter	1.48 ± 0.33	1.43 ± 0.31	1.39 ± 0.31	1.43 ± 0.18
Summer	−2.08 ± 0.48	−2.00 ± 0.46	−1.65 ± 0.38	−1.91 ± 0.25
Net	−0.61 ± 0.58	−0.57 ± 0.56	−0.26 ± 0.49	−0.48 ± 0.31
Runoff (10^6 m^3)	12.4 ± 2.8	11.9 ± 2.7	9.8 ± 1.9	11.3 ± 1.5
Model, Ille Glacier
Winter	1.55 ± 0.23	1.38 ± 0.21	1.44 ± 0.22	1.46 ± 0.13
Summer	−2.32 ± 0.42	−1.60 ± 0.29	−1.18 ± 0.21	−1.70 ± 0.18
Net	−0.77 ± 0.48	−0.22 ± 0.35	0.26 ± 0.30	−0.24 ± 0.22
Runoff (10^6 m^3)	13.8 ± 2.5	9.5 ± 1.7	7.0 ± 1.3	10.1 ± 1.1
Model, IRB
Winter	1.45 ± 0.36	1.30 ± 0.33	1.39 ± 0.35	1.38 ± 0.20
Summer	−2.68 ± 0.48	−1.91 ± 0.34	−1.43 ± 0.26	−2.01 ± 0.22
Net	−1.23 ± 0.60	−0.61 ± 0.47	−0.04 ± 0.43	−0.63 ± 0.29
Runoff (10^6 m^3)	150 ± 27	107 ± 19	80 ± 14	112 ± 12

Table 4. Monthly mean weather at the Illecillewaet Glacier AWS site, summer 2009.

Period	T min (°C)		T max (°C)	PDD (°C d)				f cs
May	−12.7	−1.3	10.2	40	72	308	0.80	0.85
June	−6.6	2.4	10.4	93	71	312	0.70	0.79
July	−6.2	5.7	15.4	191	69	300	0.62	0.80
August	−2.4	5.5	14.8	181	71	232	0.40	0.77
1–14 Sept.	−2.9	3.8	13.3	62	73	184	0.56	0.78
Season	−12.7	2.6	15.4	566	71	296	0.62	0.80

Table 5. Parameter values calibrated from field measurements.

Parameter	Description	Value	Units
βP	Winter snowpack lapse rate, 2009	0.92	mm w.e. m^−1
	Winter snowpack lapse rate, 2009–11	0.73	mm w.e. m^−1
βT	Temperature lapse rate	−0.0067	°C m^−1
TF	Temperature factor	0.9308	mm w.e. °C^−1 d^−1
SRF	Solar radiation factor	0.02974	mm w.e. m^2 W^−1 °C^−1 d^−1
τ	Atmospheric transmissivity	0.73
f cs	Average summer clear-sky index	0.80
αs	Fresh snow albedo	0.86
αi	Ice albedo	0.20
αf	Firn albedo	0.40
kdT	Regression parameter for f cs	3.08	% °C^−1
ke	Regression parameter for f cs	−2.07	% mbar^−1
DD t	Degree day threshold for snow	4.0	°C d
A	Half amplitude, diurnal ΔTd	5.8	°C
t lag	Lag time, diurnal ΔTd	2.9	hr

Fig. 5 Hourly temperature differences between the Rogers Pass AWS and Illecillewaet Glacier AWS for all days, 1 May to 14 September 2009 (asterisks), after correcting for the mean summer temperature difference between the sites (−7.8°C). The solid line shows the average temperature difference for each hour and the dashed line shows the best-fit sine wave introduced to correct for this diurnal pattern.

Fig. 6 Observed (solid) and modelled (dashed) daily mean albedo at the Illecillewaet Glacier AWS (2450 m elevation).

Fig. 7 Observed versus modelled melt (m w.e.) at the AWS and ablation stakes during the calibration and verification periods.

Fig. 8 Modelled (a) positive degree days (°C d), (b) melt (m w.e.), (c) potential direct solar radiation (W m⁻²), and (d) absorbed solar radiation (W m⁻²) on Illecillewaet Glacier, July 2009.

Table 6. Sensitivity of modelled Illecillewaet Glacier 2008–09 mass balance and runoff to parameter uncertainties and climatic conditions. The final column is the percentage of glacier runoff associated with ice and firn melt as opposed to seasonal snow.

Experiment	Mass balance (m w.e.)			Runoff (10^6 m^3)
	Bw	Bs	Bn	Total	Snow	Ice	Ice (%)
Reference (2009)	1.55	−2.32	−0.77	13.8	9.4	4.4	32
TF −1 s.e.	1.55	−2.03	−0.48	12.0	9.2	2.8	23
TF +1 s.e.	1.55	−2.59	−1.05	15.4	9.5	5.9	39
SRF −1 s.e.	1.55	−2.11	−0.56	12.6	9.3	3.2	26
SRF +1 s.e.	1.55	−2.52	−0.97	15.0	9.5	5.5	37
TF, SRF −1 s.e.	1.55	−1.83	−0.28	10.9	9.0	1.9	17
TF, SRF +1 s.e.	1.55	−2.80	−1.25	16.7	9.5	7.2	43
f cs = 0.72	1.55	−2.07	−0.52	12.3	9.3	3.0	25
f cs = 0.88	1.55	−2.52	−0.97	15.0	9.4	5.6	37
No summer snow	1.55	−2.43	−0.88	14.4	9.1	5.3	37
Random snows, N = 10	1.55	−2.33	−0.78	13.8	9.3	4.6	33
Random snows, N = 20	1.55	−2.25	−0.70	13.3	9.4	3.9	29
No Bw plateau	1.57	−2.30	−0.73	13.7	9.5	4.2	31
βP  = 0.5 mm w.e. m^−1	1.35	−2.37	−1.02	14.1	8.3	5.8	41
βP  = 1.3 mm w.e. m^−1	1.74	−2.27	−0.52	13.5	10.2	3.3	24
Climate perturbations
ΔT = −2°C	1.55	−1.38	0.17	8.2	7.5	0.7	8
ΔT = +2°C	1.55	−3.57	−2.02	21.2	9.4	11.8	56
ΔP = −20%	1.24	−2.43	−1.19	14.4	7.6	6.8	47
ΔP = +20%	1.86	−2.24	−0.38	13.3	10.8	2.5	19
ΔT = +2°C, ΔP = +20%	1.86	−3.46	−1.60	20.6	11.3	9.3	45

Fig. 9 Sensitivity of modelled Illecillewaet Glacier runoff to perturbations in (a, c) summer temperature and (b, d) winter mass balance. (a, b). Winter (blue), summer (red), and net (black) mass balance, m w.e. (c, d). Glacier runoff (10⁶ m³) from 1 May to 14 September for total runoff (black), snow melt (red), and ice melt (blue).

Table 7. Modelled glacier runoff, Q_g , which includes meltwater from the seasonal snowpack on the glaciers, Q_s , and meltwater from glacier ice and firn, Q_i . IRB yield is the total basin discharge measured at the Greeley Hydrometric station for the period of study. The proportions of basin yield resulting from total glacier melt, snowmelt, and ice melt are expressed as percentages, f_g , f_s , and f_i .

Period	Modelled Runoff (10^6 m^3)			IRB yield (10^6 m^3)	fg (%)	fs (%)	fi (%)
	Qi	Qg	Qs
2009	149.8	82.4	67.4	1037	14.4	7.9	6.5
May	2.2	2.2	0.0	180	1.2	1.2	0.0
June	23.3	23.1	0.2	364	6.4	6.3	0.1
July	62.7	46.5	16.2	271	23.1	17.2	6.0
August	54.0	10.2	43.8	166	32.5	6.1	26.4
September	7.6	0.4	7.2	55	13.8	0.7	13.1
2010	107.2	71.2	35.9	1013	10.6	7.0	3.5
May	1.8	1.8	0.0	185	1.0	1.0	0.0
June	18.2	18.1	0.1	342	5.3	5.3	0.0
July	46.1	37.9	8.2	289	16.0	13.1	2.8
August	39.7	13.2	26.5	159	24.9	8.3	16.6
September	1.4	0.3	1.1	38	3.7	0.7	3.0
2011	80.1	68.5	11.5	1380	5.8	5.0	0.8
May	0.8	0.8	0.0	242	0.3	0.3	0.0
June	10.4	10.4	0.0	464	2.2	2.2	0.0
July	24.4	24.1	0.3	421	5.8	5.7	0.1
August	35.1	28.2	6.8	202	17.4	14.0	3.4
September	9.4	5.0	4.4	51	18.4	9.8	8.5
Average, 2009–11	112.3	74.1	38.3	1143	10.3	6.6	3.6

Fig. 10 Modelled glacier runoff in the IRB, 1 May to 14 September, 2009 to 2011, partitioned into snow (red), ice (blue), and total (black) runoff.