Table S1: Hydrometric Stations Identification Number (Figure 1), Coordinates, Gauged Area, Daily Mean and Maximum Runoff

Supplemental Material Journal of Hydrometeorology Linking Atmospheric Rivers to Annual and Extreme River Runoff in British Columbia and Southeastern Alaska https://doi.org/10.1175/JHM-D-19-0281.1

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1 Supplemental Material for

2 Linking atmospheric rivers to annual and extreme river runoff in British Columbia and 3 southeastern Alaska

4 A.R. Sharma1 and S. J. Déry2

5 1Natural Resources and Environmental Studies Program, 6 University of Northern British Columbia, Prince George, British Columbia, Canada

7 2Environmental Science and Engineering Program, 8 University of Northern British Columbia, Prince George, British Columbia, Canada

9 Contents of this file

10 Figures S1 to S9 11 Tables S1 and S2 Supplementary M a t e r i a l | i

13 Figure S1: Time series of annual and seasonal maximum runoff for three selected

14 watersheds representing different hydrological regimes across BCSAK (Figure 1), WYs

15 1979-2016. The black dots indicate the AR-related maximum runoff values. The scales of

16 the y-axes are different for each panel. Supplementary M a t e r i a l | ii

18 Figure S2: (a) Distribution of the percentage of AR contribution to annual WY runoff in the

19 pluvial San Juan River using a first order estimate based on total Water Year (WY)

20 precipitation within the watershed and a direct calculation of the percentage of AR-related

21 runoff, WYs 1979-2012. White dots show the average contribution percentage, black

22 horizontal solid lines denote medians, vertical lines show the range in the contribution Supplementary M a t e r i a l | iii

23 percentage excluding outliers, and black dots show outliers defined as values >1.5 times

24 the interquartile range of the corresponding AR contribution percentage. Of note, direct

25 calculation of the AR-related runoff is only valid for pluvial watersheds because of the lag

26 between AR-related precipitation falling as snow and runoff in the nival, glacial, and the

27 hybrid watersheds. (b) Difference between the ratio of AR-related to total WY runoff and

푅 푃 28 the ratio of AR-related to total WY precipitation i.e., 퐴푅 − 퐴푅 in the pluvial San Juan 푅푇푂푇 푃푇푂푇

29 River, WYs 1979-2012. Supplementary M a t e r i a l | iv

31 Figure S3: Mean annual runoff (×103 mm year-1) at 168 hydrometric stations across

32 BCSAK, WYs 1979-2016. Supplementary M a t e r i a l | v

33 34 Figure S4: Standard deviation (SD) of the contribution of ARs to total annual runoff (%)

35 across BCSAK, WYs 1979-2012. Supplementary M a t e r i a l | vi

37 Figure S5: Percentage of AR-related annual maximum runoff due to direct contribution of

38 extreme precipitation within the extreme runoff day or previous six days across BCSAK,

39 WYs 1979-2012. Supplementary M a t e r i a l | vii

41 Figure S6: AR linkages to seasonal daily maximum runoff across BCSAK, WYs 1979-2016. Supplementary M a t e r i a l | viii

43 Figure S7: Temporal change in AR-related AM runoff percentage across BCSAK, WYs

44 1979-2016 as given by the Mann-Kendall trend test. The change over time is decreasing or

45 increasing if the p <0.05 otherwise there is no change. Supplementary M a t e r i a l | ix

47 Figure S8: Temporal change in AR-related seasonal daily maximum runoff across BCSAK,

48 WYs 1979-2016 as given by the Mann-Kendall trend test. The change over time is

49 increasing or decreasing if the p <0.05 otherwise there is no change. Supplementary M a t e r i a l | x

51 Figure S9: Mean daily air temperatures at different elevation grid cells during AR and

52 non-AR spring maximum runoff days for three selected watersheds representing the

53 pluvial, nival, and glacial hydrological regimes. Vertical solid lines show 0°C.

Supplementary M a t e r i a l | xi

54 Table S1: Hydrometric stations identification number (Figure 1), coordinates, gauged area, daily mean and maximum runoff

55 and coefficient of variation (CV) for WYs 1979-2016 in BCSAK.

STATION DAILY DAILY DAILY MEAN MEAN GAUGED GLACIER DAILY Nested STATION NUMBER LAT. LON. SLOPE MEAN MEAN MAXIMUM ANNUAL RIVER ELEVATION AREA COVERAGE MAXIMUM (Y=Yes, ID REFERENCED (°N) (°W) (°) RUNOFF RUNOFF RUNOFF RUNOFF (m) (km2) (%) RUNOFF CV N=No) TO FIGURE 1 (mm day-1) CV (mm day-1) (mm year-1) COASTAL BC AND SOUTHEASTERN ALASKA

SALMON R NR A008000 146 56.0 130.1 1228 277 37.00 23.1 9.39 0.16 170.80 0.91 3397 N HYDER LEMON C NR A052000 159 58.4 134.4 1009 32 48.00 23.3 12.82 0.04 123.92 0.30 4815 N JUNEAU MENDENHALL R A052500 160 58.4 134.6 1009 220 56.00 23.3 13.31 0.02 110.53 0.21 4936 N NR AUKE BAY TAIYA R NR A056210 166 59.5 135.3 1069 461 29.00 23.5 6.42 0.03 37.53 0.14 2340 N SKAGWAY FISH C NR A072000 134 55.4 131.2 389 90 NA 23.7 11.58 0.03 91.38 0.16 4269 N KETCHIKAN OLD TOM C NR A085100 135 55.4 132.4 331 16 NA 23.8 6.49 0.04 84.88 0.23 2546 N KASAAN STIKINE RIVER 08CE001 AT TELEGRAPH 157 57.9 131.2 1368 29300 1.66 2.5 1.21 0.03 8.72 0.15 451 Y CREEK STIKINE RIVER 08CF003 NEAR 153 56.7 132.1 1286 51600 NA 2.8 2.65 0.02 11.90 0.13 971 N WRANGELL ISKUT RIVER 08CG001 BELOW 155 56.7 131.7 1227 9350 NA 2.9 4.26 0.02 32.23 0.34 1583 Y JOHNSON RIVER SURPRISE 08DA005 CREEK NEAR 147 56.1 129.5 1276 221 35.73 2.9 6.11 0.03 42.89 0.30 2290 Y THE MOUTH NASS RIVER 08DB001 ABOVE SHUMAL 133 55.3 129.1 1091 18500 11.79 3.4 3.65 0.02 23.86 0.28 1328 N CREEK NANIKA RIVER 08ED001 AT OUTLET OF 108 53.9 127.5 1306 741 10.10 3.9 3.39 0.02 20.75 0.16 1238 Y KIDPRICE LAKE MORICE RIVER 08ED002 117 54.1 127.4 1254 1910 10.76 4.3 3.41 0.02 16.38 0.06 1230 Y NEAR HOUSTON BUCK CREEK AT 08EE013 122 54.4 126.7 1120 580 NA 4.9 0.65 0.05 10.77 0.17 237 Y THE MOUTH SKEENA RIVER 08EF001 129 54.6 128.4 1121 42200 1.47 5.2 1.85 0.02 14.54 0.13 681 N AT USK ZYMOETZ 08EF005 RIVER ABOVE 124 54.5 128.3 1179 2980 4.69 5.2 3.07 0.03 25.24 0.41 1117 N O.K. CREEK EXCHAMSIKS 08EG012 RIVER NEAR 121 54.4 129.3 878 370 14.07 5.2 10.18 0.03 98.08 0.22 3732 N TERRACE Supplementary M a t e r i a l | xii

WANNOCK RIVER AT 08FA002 84 51.7 127.2 1209 3940 23.22 5.8 7.12 0.02 36.13 0.20 2518 N OUTLET OF OWIKENO LAKE SALLOOMT 08FB004 RIVER NEAR 91 52.4 126.5 1123 161 5.89 6.3 4.74 0.03 43.57 0.35 1686 N HAGENSBORG ATNARKO 08FB006 RIVER NEAR 89 52.4 126.0 1436 2430 0.70 6.3 1.02 0.01 8.06 0.11 351 Y THE MOUTH BELLA COOLA RIVER ABOVE 08FB007 90 52.4 126.2 1491 3730 10.55 7.2 2.16 0.02 11.61 0.17 763 N BURNT BRIDGE CREEK KEMANO RIVER ABOVE 08FE003 105 53.6 127.9 1169 583 13.19 7.6 6.87 0.03 63.45 0.37 2500 N POWERHOUSE TAILRACE KITIMAT RIVER 08FF001 BELOW HIRSCH 112 54.0 128.7 830 1990 4.48 7.7 5.74 0.03 56.86 0.38 2083 N CREEK HIRSCH CREEK 08FF002 NEAR THE 113 54.1 128.6 940 347 1.45 8.4 5.42 0.03 67.97 0.43 1997 Y MOUTH LITTLE WEDEENE 08FF003 RIVER BELOW 118 54.1 128.7 762 182 0.97 9.2 7.95 0.04 81.57 0.39 3059 Y BOWBYES CREEK HOMATHKO 08GD004 RIVER AT THE 62 51.0 124.9 1645 5720 22.35 9.2 4.10 0.02 24.13 0.26 1489 N MOUTH HOMATHKO RIVER AT INLET 08GD008 81 51.7 124.4 1453 500 0.47 9.4 0.31 0.02 2.40 0.23 113 Y TO TATLAYOKO LAKE KLINAKLINI RIVER EAST 08GE002 CHANNEL 66 51.1 125.6 1511 5780 19.81 9.5 4.51 0.03 22.04 0.31 1637 N (MAIN) NEAR THE MOUTH CHEMAINUS 08HA001 RIVER NEAR 3 48.9 123.7 642 355 NA 9.9 4.60 0.06 81.34 0.27 1661 N WESTHOLME KOKSILAH RIVER AT 08HA003 2 48.7 123.7 458 209 NA 10.5 4.00 0.08 71.45 0.19 1451 N COWICHAN STATION SAN JUAN 08HA010 RIVER NEAR 1 48.6 124.3 547 580 NA 10.6 7.21 0.06 104.85 0.19 2587 N PORT RENFREW ENGLISHMAN 08HB002 RIVER NEAR 27 49.3 124.3 576 324 NA 10.8 3.59 0.08 66.01 0.28 1316 N PARKSVILLE Supplementary M a t e r i a l | xiii

SARITA RIVER 08HB014 NEAR 4 48.9 125.0 414 162 NA 10.8 10.52 0.04 198.59 0.31 3798 N BAMFIELD OYSTER RIVER BELOW 08HD011 47 49.9 125.2 914 298 0.51 10.9 4.02 0.05 53.19 0.26 1473 N WOODHUS CREEK ZEBALLOS 08HE006 RIVER NEAR 51 50.0 126.8 728 181 0.15 10.9 12.23 0.05 215.01 0.32 4285 N ZEBALLOS TSITIKA RIVER BELOW 08HF004 57 50.4 126.6 779 360 NA 10.9 5.44 0.05 76.54 0.36 1999 N CATHERINE CREEK LAVENTIE 08JA015 CREEK NEAR 106 53.6 127.5 1432 87 19.47 11.1 5.41 0.05 64.99 0.45 1939 N THE MOUTH NAHATLATCH RIVER BELOW 08MF065 49 50.0 121.9 1487 715 2.54 14.5 4.34 0.02 28.98 0.14 1583 N TACHEWANA CREEK COQUIHALLA RIVER ABOVE 08MF068 28 49.4 121.4 1205 720 NA 14.8 3.83 0.02 35.76 0.40 1380 N ALEXANDER CREEK CHEHALIS RIVER NEAR 08MG001 26 49.3 121.9 839 383 0.20 14.8 8.69 0.05 93.33 0.23 3139 N HARRISON MILLS LILLOOET 08MG005 RIVER NEAR 55 50.3 122.8 1551 2160 19.22 15.0 5.03 0.02 29.38 0.28 1786 Y PEMBERTON HARRISON RIVER NEAR 08MG013 25 49.3 121.8 1289 7870 8.25 15.0 4.87 0.01 18.62 0.09 1772 N HARRISON HOT SPRINGS CHILLIWACK RIVER AT 08MH001 16 49.1 122.0 1039 1230 NA 15.0 4.78 0.02 27.45 0.20 1684 N VEDDER CROSSING CHILLIWACK RIVER AT 08MH016 OUTLET OF 14 49.1 121.5 1267 329 NA 15.2 5.06 0.01 27.97 0.15 1839 Y CHILLIWACK LAKE SUMAS RIVER 08MH029 NEAR 9 49.0 122.2 24 149 NA 15.5 2.05 0.03 21.16 0.25 739 N HUNTINGDON SLESSE CREEK 08MH056 NEAR VEDDER 13 49.1 121.7 1079 162 NA 15.6 5.56 0.02 47.37 0.38 2046 Y CROSSING CHILLIWACK 08MH103 RIVER ABOVE 19 49.1 121.7 1251 645 NA 15.8 4.77 0.02 28.51 0.29 1698 Y SLESSE CREEK Supplementary M a t e r i a l | xiv

TULAMEEN 08NL071 RIVER BELOW 35 49.5 121.0 1554 256 NA 19.7 2.20 0.03 26.65 0.25 797 N VUICH CREEK YAKOUN RIVER 08OA002 NEAR PORT 107 53.6 132.2 213 477 NA 21.4 5.56 0.02 59.05 0.30 1990 N CLEMENTS PALLANT CREEK NEAR 08OB002 100 53.1 132.1 308 77 NA 21.4 9.16 0.02 73.60 0.29 3363 N QUEEN CHARLOTTE ATLIN RIVER 09AA006 167 59.6 133.8 1151 6810 NA 21.5 1.25 0.02 4.12 0.03 471 N NEAR ATLIN TUTSHI RIVER 09AA013 AT OUTLET OF 168 59.9 134.3 1237 992 NA 21.8 1.39 0.02 8.07 0.07 516 N TUTSHI LAKE NORTHERN INTERIOR AND PLAINS INGENIKA RIVER ABOVE 07EA004 154 56.7 125.1 1502 4200 0.01 24.0 1.20 0.04 11.31 0.21 891 N SWANNELL RIVER FINLAY RIVER 07EA005 ABOVE AKIE 156 57.1 125.3 1454 16000 NA 24.0 1.41 0.03 10.55 0.20 519 N RIVER OMINECA RIVER ABOVE 07EC002 143 55.9 124.6 1298 5490 0.05 24.4 1.42 0.03 12.86 0.13 523 N OSILINKA RIVER MESILINKA RIVER ABOVE 07EC003 148 56.2 124.6 1412 2980 0.10 24.4 1.30 0.03 11.43 0.14 480 N GOPHERHOLE CREEK PARSNIP RIVER ABOVE 07EE007 132 55.1 122.9 1139 4900 0.42 24.4 2.62 0.02 17.90 0.12 952 N MISINCHINKA RIVER CHUCHINKA 07EE009 CREEK NEAR 125 54.5 122.6 964 311 NA 24.8 1.47 0.06 18.34 0.15 519 N THE MOUTH HALFWAY 07FA003 RIVER ABOVE 151 56.5 122.2 1287 3780 NA 24.8 0.80 0.06 9.80 0.34 296 Y GRAHAM RIVER HALFWAY RIVER NEAR 07FA006 149 56.3 121.6 1141 9350 0.02 25.2 0.69 0.04 12.63 0.37 246 N FARRELL CREEK PINE RIVER AT 07FB001 141 55.7 121.2 1154 12100 0.18 25.3 1.37 0.03 15.81 0.27 482 N EAST PINE MURRAY RIVER 07FB002 NEAR THE 140 55.6 121.2 1221 5620 0.40 25.5 1.29 0.02 11.96 0.20 474 Y MOUTH SUKUNKA 07FB003 RIVER NEAR 139 55.5 121.6 1206 2510 NA 25.5 1.91 0.02 21.12 0.16 703 Y THE MOUTH Supplementary M a t e r i a l | xv

DICKEBUSCH 07FB004 CREEK NEAR 138 55.5 121.6 1100 86 NA 25.6 0.62 0.11 32.17 0.85 226 Y THE MOUTH MURRAY RIVER ABOVE 07FB006 131 55.1 121.0 1328 2410 0.93 25.7 2.07 0.02 18.35 0.20 758 Y WOLVERINE RIVER BEATTON 07FC001 RIVER NEAR 150 56.3 120.7 800 15600 NA 26.3 0.30 0.08 6.86 0.22 105 N FORT ST. JOHN BLUEBERRY 07FC003 RIVER BELOW 152 56.7 121.2 829 1750 NA 26.4 0.26 0.13 11.93 0.40 92 Y AITKEN CREEK KISKATINAW 07FD001 RIVER NEAR 144 56.0 120.6 913 3570 NA 28.6 0.24 0.10 9.75 0.74 88 N FARMINGTON POUCE COUPE RIVER BELOW 07FD007 142 55.9 120.0 784 2850 NA 29.3 0.21 0.18 13.05 0.95 69 N HENDERSON CREEK TUYA RIVER NEAR 08CD001 158 58.1 130.8 1194 3600 NA 1.0 0.90 0.07 10.24 0.20 324 Y TELEGRAPH CREEK KISPIOX RIVER 08EB004 NEAR 137 55.4 127.7 858 1870 0.68 3.5 2.07 0.04 18.20 0.41 755 Y HAZELTON BABINE RIVER AT OUTLET OF 08EC013 136 55.4 126.7 1006 6790 0.02 3.6 0.65 0.01 3.13 0.03 231 Y NILKITKWA LAKE BULKLEY RIVER 08EE004 128 54.6 126.9 1092 7360 2.80 4.5 1.58 0.02 10.12 0.09 567 Y AT QUICK GOATHORN 08EE008 CREEK NEAR 130 54.6 127.1 1245 132 0.40 4.5 1.15 0.03 12.34 0.32 420 Y TELKWA TELKWA RIVER 08EE020 BELOW TSAI 126 54.6 127.5 1353 368 6.99 5.2 3.36 0.03 24.49 0.30 1227 Y CREEK DRIFTWOOD RIVER ABOVE 08JD006 145 56.0 126.7 1212 407 0.31 11.4 1.78 0.04 17.66 0.26 653 Y KASTBERG CREEK STUART RIVER 08JE001 NEAR FORT ST. 123 54.4 124.3 973 14600 0.03 11.4 0.76 0.01 3.32 0.05 279 N JAMES TSILCOH RIVER 08JE004 NEAR THE 127 54.6 124.2 845 414 NA 11.5 0.54 0.11 7.80 0.16 192 N MOUTH MCGREGOR RIVER AT 08KB003 119 54.2 121.7 1374 4770 4.71 12.0 3.91 0.02 25.71 0.17 1345 Y LOWER CANYON Supplementary M a t e r i a l | xvi

MULLER CREEK 08KB006 NEAR THE 120 54.3 121.0 1378 134 0.99 12.1 3.04 0.03 26.64 0.21 1110 N MOUTH COTTONWOOD 10AC005 RIVER ABOVE 162 59.1 129.8 1392 888 NA 21.9 1.82 0.04 16.14 0.16 658 Y BASS CREEK LIARD RIVER AT 10BE001 LOWER 164 59.4 126.1 1213 104000 NA 22.5 0.94 0.02 6.17 0.09 348 N CROSSING TOAD RIVER 10BE004 ABOVE NONDA 161 58.9 125.4 1587 2570 2.76 22.6 1.44 0.02 11.76 0.27 529 N CREEK TROUT RIVER AT KILOMETRE 10BE007 163 59.3 125.9 1373 1190 0.27 22.9 1.18 0.02 8.89 0.35 436 N 783.7 ALASKA HIGHWAY TEETER CREEK 10BE009 NEAR THE 165 59.5 126.2 1022 211 NA 23.0 0.47 0.01 2.36 0.18 173 Y MOUTH INTERIOR MOUNTAINS DORE RIVER 08KA001 103 53.3 120.2 1877 404 17.95 11.5 3.04 0.03 22.19 0.16 1085 Y NEAR MCBRIDE FRASER RIVER 08KA004 114 54.1 121.8 1465 18000 4.23 11.5 2.21 0.02 12.35 0.08 778 Y AT HANSARD FRASER RIVER 08KA005 101 53.3 120.1 1770 6890 8.59 11.5 2.46 0.02 13.87 0.08 889 Y AT MCBRIDE FRASER RIVER 08KA007 99 53.0 119.0 1905 1700 5.17 11.5 2.31 0.02 16.15 0.10 830 Y AT RED PASS MCKALE RIVER 08KA009 NEAR 940 M 104 53.4 120.2 1796 252 6.88 11.6 2.84 0.03 23.38 0.21 1037 Y CONTOUR BOWRON RIVER 08KD007 BELOW BOX 111 54.0 122.1 1209 3420 0.17 12.1 1.84 0.02 11.70 0.12 644 Y CANYON QUESNEL RIVER 08KH001 92 52.6 121.6 1298 5930 1.80 12.2 1.88 0.02 8.42 0.03 694 N AT LIKELY CARIBOO RIVER BELOW 08KH003 93 52.7 121.7 1395 3260 NA 12.6 0.52 0.02 3.82 0.10 189 Y KANGAROO CREEK HORSEFLY RIVER ABOVE 08KH010 87 52.3 121.1 1502 785 0.09 12.8 2.17 0.02 15.88 0.10 783 Y MCKINLEY CREEK MOFFAT CREEK 08KH019 NEAR 88 52.3 121.4 1202 539 NA 12.9 0.55 0.04 5.89 0.22 199 Y HORSEFLY NORTH THOMPSON 08LB047 77 51.6 119.9 1528 4450 6.47 13.1 2.95 0.02 16.45 0.08 1074 Y RIVER AT BIRCH ISLAND ADAMS RIVER 08LD001 61 50.9 119.7 1261 3080 1.79 13.4 1.99 0.02 10.19 0.05 730 Y NEAR SQUILAX Supplementary M a t e r i a l | xvii

SEYMOUR 08LE027 RIVER NEAR 70 51.3 118.9 1390 805 2.52 13.6 3.91 0.03 26.84 0.16 1425 Y SEYMOUR ARM COLUMBIA 08NA002 RIVER AT 68 51.2 116.9 1751 6660 5.99 15.8 1.41 0.02 8.79 0.10 498 N NICHOLSON KICKING HORSE 08NA006 RIVER AT 72 51.3 117.0 1935 1850 5.07 15.9 1.89 0.03 13.52 0.14 688 Y GOLDEN COLUMBIA 08NB005 RIVER AT 75 51.5 117.2 1779 9710 5.61 16.0 1.53 0.02 8.62 0.13 541 N DONALD BLAEBERRY RIVER ABOVE 08NB012 74 51.5 117.0 1959 588 8.73 16.1 2.46 0.03 15.87 0.13 895 Y WILLOWBANK CREEK GOLD RIVER 08NB014 ABOVE PALMER 83 51.7 117.7 2030 427 18.88 16.1 3.69 0.03 22.84 0.12 1351 N CREEK SPLIT CREEK AT 08NB016 76 51.5 116.9 1986 81 NA 16.2 1.76 0.02 12.62 0.16 637 Y THE MOUTH CANOE RIVER 08NC004 BELOW KIMMEL 94 52.7 119.4 1922 298 25.81 16.3 4.31 0.03 24.21 0.13 1564 N CREEK GOLDSTREAM RIVER BELOW 08ND012 80 51.7 118.6 1655 938 8.52 16.5 3.58 0.02 23.22 0.11 1284 N OLD CAMP CREEK ILLECILLEWAET 08ND013 RIVER AT 63 51.0 118.1 1724 1170 9.76 16.9 3.91 0.02 24.10 0.10 1413 N GREELEY KUSKANAX 08NE006 CREEK NEAR 54 50.3 117.7 1638 337 0.08 17.0 3.57 0.02 41.10 0.28 1267 N NAKUSP BIG SHEEP 08NE039 CREEK NEAR 10 49.0 117.9 1390 347 NA 17.0 1.40 0.03 16.01 0.12 497 N ROSSLAND SALMO RIVER 08NE074 11 49.0 117.3 1445 1230 NA 17.2 2.24 0.02 20.86 0.14 809 N NEAR SALMO DEER CREEK AT 08NE087 31 49.4 118.0 1368 81 NA 17.2 0.97 0.03 11.84 0.13 351 N DEER PARK HIDDEN CREEK 08NE114 NEAR THE 23 49.2 117.2 1538 57 NA 17.3 2.49 0.03 23.58 0.21 893 Y MOUTH KOOTENAY RIVER AT 08NF001 60 50.9 116.0 1742 420 0.58 17.3 0.99 0.02 9.50 0.09 358 N KOOTENAY CROSSING KOOTENAY 08NG065 RIVER AT FORT 38 49.6 115.6 1742 11400 0.61 17.3 1.31 0.02 11.06 0.12 466 N STEELE MATHER CREEK 08NG076 BELOW HOULE 40 49.7 115.9 1634 136 NA 17.5 0.85 0.03 8.93 0.24 296 Y CREEK Supplementary M a t e r i a l | xviii

ST. MARY RIVER 08NG077 BELOW MORRIS 41 49.7 116.4 1862 206 NA 17.5 3.00 0.03 28.62 0.15 1090 Y CREEK MOYIE RIVER 08NH006 7 49.0 116.2 1450 1480 NA 17.5 1.13 0.03 12.09 0.13 389 N AT EASTPORT LARDEAU 08NH007 RIVER AT 53 50.3 117.0 1660 1620 NA 17.5 3.13 0.02 19.12 0.09 1117 N MARBLEHEAD DUCK CREEK 08NH016 NEAR 21 49.2 116.5 1504 57 NA 17.7 1.34 0.02 10.45 0.10 490 N WYNNDEL BOUNDARY 08NH032 CREEK NEAR 6 49.0 116.6 1433 251 NA 17.8 1.95 0.03 23.30 0.12 727 N PORTHILL ARROW CREEK 08NH084 NEAR 20 49.2 116.5 1537 79 NA 18.1 1.88 0.02 19.31 0.13 675 N ERICKSON DUNCAN RIVER 08NH119 BELOW B.B. 58 50.6 117.0 1887 1330 16.58 18.1 4.05 0.03 25.96 0.11 1468 N CREEK MOYIE RIVER 08NH120 ABOVE NEGRO 30 49.4 115.9 1689 240 NA 18.3 1.72 0.03 23.47 0.18 584 Y CREEK FRY CREEK 08NH130 BELOW CARNEY 52 50.1 116.8 2003 461 6.03 18.3 3.63 0.03 30.16 0.17 1293 N CREEK KEEN CREEK BELOW 08NH132 44 49.9 117.1 1956 92 2.19 18.5 3.13 0.03 26.91 0.19 1136 N KYAWATS CREEK SLOCAN RIVER NEAR 08NJ013 34 49.5 117.6 1551 3320 1.02 18.5 2.33 0.02 16.18 0.08 867 N CRESCENT VALLEY LEMON CREEK 08NJ160 ABOVE SOUTH 39 49.7 117.4 1668 178 NA 18.5 2.30 0.03 23.54 0.26 824 Y LEMON CREEK ELK RIVER AT 08NK002 36 49.5 115.1 1851 3110 0.75 18.6 1.32 0.02 13.72 0.22 464 N FERNIE ELK RIVER 08NK016 43 49.9 114.9 1951 1870 0.62 18.7 1.21 0.02 12.87 0.27 417 Y NEAR NATAL FORDING RIVER 08NK018 46 49.9 114.9 1954 619 NA 18.8 1.12 0.03 14.37 0.28 397 Y AT THE MOUTH LINE CREEK AT 08NK022 45 49.9 114.8 1950 138 NA 18.8 1.33 0.03 16.84 0.24 466 Y THE MOUTH KETTLE RIVER 08NN012 5 49.0 118.2 1334 9840 NA 20.7 0.73 0.03 6.85 0.11 271 Y NEAR LAURIER FLATHEAD 08NP001 RIVER AT 8 49.0 114.5 1740 1110 NA 20.9 1.96 0.02 23.96 0.19 686 N FLATHEAD CABIN CREEK 08NP004 NEAR THE 15 49.1 114.6 1793 93 NA 21.1 1.83 0.04 21.01 0.15 660 Y MOUTH SOUTHERN INTERIOR Supplementary M a t e r i a l | xix

DEAN RIVER BELOW 08FC003 96 52.9 125.8 1350 3780 NA 7.6 0.44 0.03 5.35 0.20 134 N TANSWANKET CREEK STELLAKO 08JB002 RIVER AT 110 54.0 125.0 970 3600 0.19 11.2 0.50 0.01 4.07 0.05 165 N GLENANNAN NAUTLEY RIVER 08JB003 NEAR FORT 115 54.1 124.6 950 6030 0.12 11.4 0.45 0.02 3.76 0.06 150 N FRASER FRASER RIVER 08KB001 109 54.0 122.6 1281 32400 3.04 11.7 2.16 0.02 11.23 0.09 776 N AT SHELLEY SALMON RIVER 08KC001 NEAR PRINCE 116 54.1 122.7 849 4300 NA 12.1 0.59 0.05 6.73 0.11 203 Y GEORGE BAKER CREEK 08KE016 98 53.0 122.5 1095 1570 NA 12.1 0.29 0.06 4.59 0.15 101 N AT QUESNEL LITTLE SWIFT 08KE024 RIVER AT THE 97 52.9 121.8 1461 133 NA 12.1 1.82 0.03 20.55 0.20 659 N MOUTH WEST ROAD 08KG001 RIVER NEAR 102 53.3 122.9 1162 12400 NA 12.2 0.26 0.03 2.46 0.08 87 N CINEMA QUESNEL RIVER 08KH006 95 52.8 122.2 1271 11500 2.28 12.8 1.78 0.02 7.93 0.04 661 N NEAR QUESNEL CLEARWATER RIVER NEAR 08LA001 79 51.7 120.1 1357 10200 2.37 12.9 1.91 0.02 10.76 0.06 691 N CLEARWATER STATION BARRIERE 08LB020 RIVER AT THE 67 51.2 120.1 1281 1140 NA 12.9 1.12 0.01 9.92 0.12 403 N MOUTH FISHTRAP 08LB024 CREEK NEAR 65 51.1 120.2 1266 135 NA 13.0 0.50 0.04 7.03 0.23 179 Y MCLURE NORTH THOMPSON 08LB064 64 51.0 120.2 1369 19600 2.72 13.1 1.89 0.02 10.21 0.08 682 N RIVER AT MCLURE BARRIERE RIVER BELOW 08LB069 69 51.2 119.9 1431 624 NA 13.3 1.57 0.02 15.66 0.19 576 Y SPRAGUE CREEK HARPER CREEK 08LB076 NEAR THE 73 51.4 119.9 1631 168 NA 13.3 2.06 0.03 19.30 0.15 736 Y MOUTH SOUTH THOMPSON 08LE031 59 50.8 119.7 1196 16200 0.63 13.6 1.57 0.02 7.80 0.05 593 N RIVER AT CHASE THOMPSON RIVER NEAR 08LF051 56 50.4 121.4 1253 54900 1.14 13.7 1.20 0.02 5.97 0.05 439 N SPENCES BRIDGE Supplementary M a t e r i a l | xx

PENNASK 08LG016 CREEK NEAR 50 50.0 120.1 1679 87 NA 13.8 0.73 0.05 15.05 0.23 259 Y QUILCHENA COLDWATER 08LG048 RIVER NEAR 42 49.9 120.9 1429 316 NA 14.1 1.86 0.02 20.90 0.17 664 Y BROOKMERE CHILKO RIVER 08MA001 NEAR 86 52.1 123.5 1635 6940 6.77 14.1 1.11 0.02 5.48 0.06 397 Y REDSTONE CHILKO RIVER 08MA002 AT OUTLET OF 78 51.6 124.1 1748 2110 9.30 14.1 1.79 0.02 7.84 0.02 648 Y CHILKO LAKE LINGFIELD 08MA006 CREEK NEAR 82 51.7 124.1 1773 98 NA 14.3 0.68 0.04 12.97 0.21 255 Y THE MOUTH CHILCOTIN 08MB005 RIVER BELOW 85 51.8 122.7 1402 19300 2.51 14.4 0.46 0.02 2.43 0.12 168 N BIG CREEK BIG CREEK BELOW 08MB007 71 51.3 123.1 2124 232 3.07 14.5 1.02 0.02 11.31 0.31 378 Y GRAVEYARD CREEK INONOAKLIN 08NE110 CREEK ABOVE 48 49.9 118.2 1442 298 NA 17.3 3.81 0.03 32.21 0.14 1366 N VALLEY CREEK ASHNOLA 08NL004 RIVER NEAR 22 49.2 120.0 1794 1050 NA 18.9 0.65 0.02 11.30 0.14 219 N KEREMEOS SIMILKAMEEN 08NL007 RIVER AT 32 49.5 120.5 1487 1850 NA 19.1 1.11 0.02 16.80 0.14 382 Y PRINCETON TULAMEEN 08NL024 RIVER AT 33 49.5 120.5 1352 1760 NA 19.1 1.08 0.02 13.32 0.17 360 Y PRINCETON SIMILKAMEEN 08NL038 RIVER NEAR 29 49.4 120.2 1379 5590 NA 19.3 0.74 0.02 7.52 0.16 264 N HEDLEY PASAYTEN 08NL069 RIVER ABOVE 17 49.1 120.6 1633 562 NA 19.3 1.25 0.03 13.09 0.17 451 Y CALCITE CREEK SIMILKAMEEN RIVER ABOVE 08NL070 18 49.1 120.7 1622 407 NA 19.5 1.68 0.03 18.14 0.15 600 Y GOODFELLOW CREEK VASEUX CREEK 08NM171 ABOVE SOLCO 24 49.2 119.3 1700 117 NA 19.7 0.67 0.05 11.64 0.17 242 N CREEK GRANBY RIVER 08NN002 AT GRAND 12 49.0 118.4 1373 2050 NA 20.6 1.29 0.03 12.62 0.12 467 Y FORKS BURRELL CREEK ABOVE 08NN023 37 49.6 118.3 1474 224 NA 20.8 1.65 0.03 17.96 0.10 599 Y GLOUCESTER CREEK

Supplementary M a t e r i a l | xxi

56 Table S2: Mann-Whitney-Wilcoxon (MWW) test results of the distribution of AR-related and non-AR-related annual daily

57 maximum discharge for 168 watersheds across BCSAK, WYs 1979-2016. The mean is rounded to their closest whole number.

58 Column MWW indicate whether the hypothesis Is the mean amount of AR-related daily maximum discharge significantly greater

59 than non-AR-related discharge rejected or accepted at p <0.05.

MEAN MEAN STATION AR-RELATED AR-RELATED NON-AR-RELATED NON-AR-RELATED NUMBER DAILY STATION ID DISCHARGE DAILY MAXIMUM DISCHARGE WSCORE P-VALUE MWW REFERENCED MAXIMUM NUMBER DISCHARGE NUMBER TO FIGURE 1 DISCHARGE (mm day-1) (mm day-1) COASTAL BC AND SOUTHEASTERN ALASKA A008000 146 63 21 79 17 147 0.92 no A052000 159 92 28 43 10 215 0.00 yes A052500 160 95 36 42 2 72 0.01 yes A056210 166 29 20 22 18 230 0.04 yes A072000 134 71 37 49 1 34 0.09 no A085100 135 79 37 52 1 35 0.07 no 08CE001 157 7 12 6 26 187 0.17 no 08CF003 153 10 20 10 18 217 0.14 no 08CG001 155 24 26 17 12 249 0.00 yes 08DA005 147 38 25 29 13 254 0.00 yes 08DB001 133 18 19 15 19 233 0.07 no 08ED001 108 16 18 15 20 198 0.30 no 08ED002 117 12 17 11 21 191 0.37 no 08EE013 122 7 6 6 32 118 0.20 no 08EF001 129 10 20 9 18 238 0.05 yes 08EF005 124 23 19 16 19 254 0.02 yes 08EG012 121 75 36 47 2 65 0.03 yes 08FA002 84 27 38 yes 08FB004 91 33 37 20 1 26 0.26 no 08FB006 89 5 19 5 19 174 0.59 no 08FB007 90 9 26 7 12 240 0.00 yes 08FE003 105 53 33 37 5 127 0.03 yes 08FF001 112 48 36 30 2 63 0.04 yes Supplementary M a t e r i a l | xxii

08FF002 113 51 36 30 2 57 0.09 no 08FF003 118 68 37 48 1 30 0.16 no 08GD004 62 21 26 17 12 188 0.16 no 08GD008 81 2 12 2 26 159 0.47 no 08GE002 66 19 28 16 10 174 0.14 no 08HA001 3 66 38 yes 08HA003 2 62 38 yes 08HA010 1 83 38 yes 08HB002 27 57 37 10 1 37 0.05 no 08HB014 4 151 38 yes 08HD011 47 40 38 yes 08HE006 51 139 38 yes 08HF004 57 63 38 yes 08JA015 106 52 30 34 8 185 0.01 yes 08MF065 49 25 26 24 12 182 0.21 no 08MF068 28 27 28 17 10 202 0.02 yes 08MG001 26 79 37 15 1 37 0.03 yes 08MG005 55 24 33 19 5 116 0.08 no 08MG013 25 13 21 13 17 176 0.54 no 08MH001 16 22 35 20 3 61 0.34 no 08MH016 14 22 26 18 12 199 0.09 no 08MH029 9 16 34 15 4 65 0.57 no 08MH056 13 38 35 26 3 85 0.04 yes 08MH103 19 23 30 16 8 170 0.04 yes 08NL071 35 26 17 18 21 259 0.01 yes 08OA002 107 43 38 yes 08OB002 100 54 38 yes 09AA006 167 3 23 3 15 182 0.40 no 09AA013 168 4 1 6 37 3 0.93 no NORTHERN INTERIOR AND PLAINS 07EA004 154 9 5 8 33 102 0.21 no 07EA005 156 8 8 8 30 111 0.64 no 07EC002 143 10 9 10 29 133 0.47 no 07EC003 148 9 5 8 33 92 0.35 no 07EE007 132 15 16 15 22 195 0.29 no 07EE009 125 15 11 13 27 163 0.33 no 07FA003 151 6 4 6 34 67 0.53 no 07FA006 149 7 9 7 29 147 0.29 no 07FB001 141 12 15 10 23 209 0.14 no 07FB002 140 9 18 9 20 192 0.37 no 07FB003 139 17 16 17 22 172 0.55 no 07FB004 138 13 8 18 30 110 0.64 no Supplementary M a t e r i a l | xxiii

07FB006 131 15 17 13 21 229 0.07 no 07FC001 150 5 13 3 25 255 0.00 yes 07FC003 152 9 12 5 26 241 0.00 yes 07FD001 144 6 10 4 28 177 0.12 no 07FD007 142 10 5 4 33 78 0.59 no 08CD001 158 8 18 7 20 206 0.23 no 08EB004 137 16 16 12 22 233 0.05 yes 08EC013 136 2 7 2 31 109 0.51 no 08EE004 128 7 14 7 24 199 0.18 no 08EE008 130 9 12 9 26 172 0.32 no 08EE020 126 25 13 18 25 254 0.00 yes 08JD006 145 15 12 13 26 181 0.22 no 08JE001 123 2 13 2 25 199 0.13 no 08JE004 127 6 6 6 32 94 0.55 no 08KB003 119 22 17 19 21 246 0.03 yes 08KB006 120 24 13 21 25 220 0.04 yes 10AC005 162 16 6 12 32 144 0.03 yes 10BE001 164 5 15 4 23 213 0.12 no 10BE004 161 8 12 8 26 151 0.57 no 10BE007 163 6 9 5 29 128 0.54 no 10BE009 165 1 10 1 28 129 0.65 no INTERIOR MOUNTAINS 08KA001 103 17 22 15 16 238 0.04 yes 08KA004 114 10 16 9 22 220 0.10 no 08KA005 101 12 16 10 22 243 0.02 yes 08KA007 99 13 15 11 23 224 0.06 no 08KA009 104 21 13 19 25 216 0.05 no 08KD007 111 10 19 8 19 253 0.02 yes 08KH001 92 6 17 6 21 202 0.25 no 08KH003 93 3 14 3 24 218 0.07 no 08KH010 87 14 13 12 25 202 0.12 no 08KH019 88 4 8 4 30 159 0.09 no 08LB047 77 13 18 13 20 217 0.15 no 08LD001 61 6 21 7 17 152 0.79 no 08LE027 70 23 25 20 13 226 0.03 yes 08NA002 68 6 25 5 13 188 0.22 no 08NA006 72 11 19 10 19 238 0.05 yes 08NB005 75 6 25 6 13 183 0.27 no 08NB012 74 13 17 11 21 233 0.06 no 08NB014 83 21 22 18 16 233 0.05 yes 08NB016 76 10 18 10 20 176 0.55 no 08NC004 94 22 26 21 12 162 0.43 no Supplementary M a t e r i a l | xxiv

08ND012 80 18 18 17 20 204 0.25 no 08ND013 63 20 22 18 16 231 0.05 no 08NE006 54 22 18 22 20 199 0.29 no 08NE039 10 10 9 12 29 85 0.94 no 08NE074 11 16 11 16 27 148 0.52 no 08NE087 31 10 10 8 28 212 0.01 yes 08NE114 23 18 11 18 27 144 0.56 no 08NF001 60 7 11 6 27 180 0.16 no 08NG065 38 7 23 7 15 153 0.73 no 08NG076 40 6 10 6 28 132 0.61 no 08NG077 41 25 15 22 23 224 0.06 no 08NH006 7 8 13 8 25 160 0.54 no 08NH007 53 14 14 13 24 202 0.15 no 08NH016 21 8 8 7 30 128 0.40 no 08NH032 6 17 13 17 25 162 0.51 no 08NH084 20 14 10 14 28 130 0.64 no 08NH119 58 25 17 20 21 297 0.00 yes 08NH120 30 20 13 15 25 232 0.02 yes 08NH130 52 26 15 24 23 231 0.04 yes 08NH132 44 25 18 21 20 269 0.00 yes 08NJ013 34 12 14 11 24 200 0.17 no 08NJ160 39 18 11 16 27 198 0.06 no 08NK002 36 7 13 8 25 166 0.46 no 08NK016 43 7 14 8 24 164 0.55 no 08NK018 46 8 11 8 27 167 0.29 no 08NK022 45 9 13 10 25 170 0.42 no 08NN012 5 5 11 5 27 151 0.48 no 08NP001 8 15 8 13 30 159 0.09 no 08NP004 15 19 15 16 23 244 0.02 yes SOUTHERN INTERIOR 08FC003 96 4 11 2 27 189 0.10 no 08JB002 110 2 5 1 33 110 0.13 no 08JB003 115 2 11 1 27 187 0.11 no 08KB001 109 9 20 8 18 226 0.09 no 08KC001 116 5 6 4 32 143 0.03 yes 08KE016 98 3 8 3 30 156 0.10 no 08KE024 97 20 10 15 28 218 0.01 yes 08KG001 102 2 10 1 28 192 0.04 yes 08KH006 95 6 12 6 26 135 0.75 no 08LA001 79 8 13 8 25 169 0.43 no 08LB020 67 8 13 7 25 185 0.25 no 08LB024 65 4 12 5 26 142 0.68 no Supplementary M a t e r i a l | xxv

08LB064 64 8 15 8 23 176 0.47 no 08LB069 69 11 14 11 24 164 0.56 no 08LB076 73 16 7 16 31 113 0.45 no 08LE031 59 5 20 5 18 198 0.30 no 08LF051 56 4 21 4 17 204 0.23 no 08LG016 50 8 13 8 25 168 0.44 no 08LG048 42 17 23 15 15 205 0.17 no 08MA001 86 4 19 4 19 119 0.96 no 08MA002 78 5 25 6 13 78 1.00 no 08MA006 82 7 19 8 19 133 0.92 no 08MB005 85 1 15 2 23 109 0.97 no 08MB007 71 6 14 8 24 143 0.78 no 08NE110 48 26 15 23 23 227 0.06 no 08NL004 22 5 9 5 29 133 0.47 no 08NL007 32 8 15 9 23 176 0.46 no 08NL024 33 10 17 8 21 257 0.01 yes 08NL038 29 5 17 6 21 179 0.50 no 08NL069 17 10 15 10 23 186 0.35 no 08NL070 18 15 16 14 22 203 0.22 no 08NM171 24 6 9 8 29 93 0.91 no 08NN002 12 9 9 10 29 124 0.60 no 08NN023 37 13 9 15 29 108 0.79 no