Flood of August 1950 

in the Waimea Area 

Kauai, Hawaii

> R. K. CHUN 

:^LOODS OF 1950

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1137-C

^repared in cooperation with the 

Territory of Hawaii

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1952
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 15 cents (paper cover)
PREFACE

This report on the flood of August 1950 in Kauai, 

T. H., was prepared in the Surface Water Branch, 

J. V. B. Wells, Chief. The material was assembled and the text was written by R. K. Chun, 

hydraulic engineer, under the immediate supervision of M. H. Carson, District Engineer.

Base data used in this report were collected in 

cooperation with the Territory of Hawaii. The 

Weather Bureau furnished a discussion on the 

meteorology of the storm and a map showing the 

path of the hurricane. The collection of data for 

indirect determination of peak discharges was 

supervised, and the computations made, by 

Hollister Johnson, hydraulic engineer.

Ill

CONTENTS

Page

Introduction ..................................................... 327

Stages and discharges at stream-gaging stations ..................... 327

Waimea River near Waimea, Kauai .............................. 331

Kawaikoi Stream near Waimea, Kauai ............................ 332

Mohihi Stream near Waimea/ Kauai .............................. 333

Makaweli River near Waimea, Kauai ............................. 334

Combined discharge of Waimea and Makaweli Rivers ............... 335

Summary of flood data ............................................ 337

Flood stages and discharges ..................................... 337

Annual floods in Waimea River ................................... 337

Physical features of Kauai'........................................ 342

Meteorological features of the flood ................................ 343

Precipitation................................................... 343

Meteorology, by R. H. Simpson, United States Weather Bureau ..... 344

ILLUSTRATIONS

Page 

Figure 46. Map showing location of flood determinations and rain

gages, and isohyetal lines for the period August 14-19,

1950 .............................................. 328

47. Graphs of hourly discharge, 1950 ....................... 330

48. Relation of unit discharge to size of drainage area ........ 336

49. United States Weather Bureau map showing path of

hurricane "Hiki, " August 1950. ........................ 345

TABLES

Page 

Table 1. Summary of flood stages and discharges in Kauai, T. H.,

in August 1950 ....................................... 338

2. Annual floods in Waimea River, for years ending June 30 . . 341

3. Daily precipitation, in inches, August 14-19, 1950 ........ 344

FLOODS OF 1950

FLOOD OF AUGUST 1950 IN THE WAIMEA AREA 

KAUAI, HAWAII

By R. K. CHUN

INTRODUCTION

On August 15-18,' 1950, Waimea River on the island of Kauai, 

T. H., had one of the severest floods in its history as a result of torrential rains, caused by a storm associated with the only typhoon ever 

recorded in the proximity of the Hawaiian Archipelego.- At one rainfall station in the basin, 50 inches of rain was recorded during a 72- 

hour period. Kawaikoi Stream, in the headwaters of Waimea River 

basin, reached a maximum discharge of 7, 980 second-feet, or 1,950 

second-feet per square mile.

A rubble wall along the right bank of Waimea River just below the 

mouth of Makaweli River, constructed to contain the flow, was overtopped and the entire town of Waimea was flooded. The. water was 

about a foot over the top of the wall at most places. No lives were 

lost, but damage to property was about $200, 000.

This report presents detailed records of stages and discharges at 

four gaging stations in the basin during the flood period August 15-18 

in the Waimea River basin, a summary of flood discharges at gaging 

stations on the principal streams on the island of Kauai, a description 

of the physical features of the drainage basin, a description of the two 

types of storms that prevail on the Hawaiian Islands, and a section on 

the meteorology of the storm of August 15-18. Figure 46 is a map of 

the island of Kauai, which shows the location of the gaging stations referred to in this report, the location of .rain gages in the area where 

rainfall was the greatest, and lines of equal rainfall for the period 

August 14-19, 1950.

STAGES AND DISCHARGES AT STREAM-GAGING STATIONS

Records of daily mean discharge for the year July 1950 to June 

1951 at gaging stations covered by this report will be found in a forth327
Figure 46. --Map showing location of flood determinations and rain gages, and 

isohvetal lines for the oeriod August 14-19, 1950.
STAGES AND DISCHARGES AT STREAM -GAGING STATIONS 329

coming Geological Survey water-supply paper, Surface Water Supply 

of Hawaii, 1950-51. Daily mean discharge, however, is generally 

insufficient for the detailed analysis involved in flood studies, which 

require knowledge of the rate of discharge and corresponding stages 

at more frequent intervals. The main purpose of this report is to 

provide such detailed information.

Detailed records of discharge for the gaging stations in Waimea 

River basin appear on the following pages. For each station, the 

records include a description of the gaging station, daily mean discharge, and total runoff for the"4-day period August 15-18, and hourly gage height and discharge for the 4-day period. Hydrographs for 

Waimea River near Waimea and Makaweli River near Waimea for the 

4-day period are plotted in figure 47.

As peak discharges were much greater than the range covered by 

the stage-discharge relation as defined by current-meter measurements, it was necessary to determine the peak discharge by some indirect method--in this case, by the slope-area method. A fuller description of the slope-area method is presented in Water-Supply Papers 

773-E, 796-G, 798, 799, 800, 816, 843, and 888.

206719 O- 52 - 2
DISCHARGE, IN THOUSANDS OF S
STAGES AND DISCHARGES AT STREAM-GAGING STATIONS 331

Waimea River near Waimea, Kauai

Location. --Lat 21°58'55", long. 15Q°39'5Q n ,13 miles upstream from confluence 

with Makaweli River and 1.8 miles north of Waimea. Altitude of gage, 25 ft 

(hand levels from estuary at confluence with Makaweli River).

Drainage area. --57. 8 sq mi.

Gage-height record. --Water-stage recorder graph except for periods 3 a.m. to 

5 p. m" Aug. 16, 5 a. m. to 1 p. m. Aug. 17, and 7 a. m. to 12 p. m. Aug. 18, 

record for which was based on readings on Aug. 16 and 17, current-meter 

measurement on the 18th, and shape of stage graphs at nearby streams.

Discharge record. --Stage-discharge relation defined by current-meter measurements below 5, 100 cfs (3, 300 mgd) and extended by logarithmic plotting 

on basis of slope-area determinations at gage heights 10. 28 ft, 13. 6 ft, and 

19. 0 ft. Gage heights used to half-tenths between 3. 0 and 4. 2 ft, hundredths 

below and tenths above those limits.

Maxima. --August 1950: Discharge, 34, 000 cfs (22, 000 mgd) 6 a. m. Aug. 17, 

r9~5TT(gage height, 18. 7 ft).

1943 to July 1950: Discharge, 37, 100 cfs (24, 000 mgd) 2:30 p. m. Feb. 7, 

1949 (gage height, 19. 3 ft), from rating curve extended above 5, 100 cfs by 

logarithmic plotting on basis of slope-area determinations at gage heights 

10. 28 ft, 13. 6 ft, and 19. 0 ft.

Mean discharge and runoff. August 15-18, 1950

Day

August 15 

13

Cfs

4,760 

17,400

Day

August 17 

18

Cfs

15,500 

2,820

Mean discharge, in cfs, for period ... 10, 100 

Runoff, in inches ................... 26. 0

Gage height and discharge at indicated time, 1950

Hour

1

2

3

4

5

6

7

8

9

10

11

N

1

2

3

4

5

6

7

8

9

10

11

12

August 15

Gage 

height 

(ft)

1.45

1.46

1.46

1.46

1.47

1.47

1,47

1.48

2.55

3.00

3.74

4.03

4.20

6.20

7.00

6.36

6. 15

9.70

14.48

14.00

13.80

14.50

16.00

17.50

k , Discharge 

(cfs)

2.24

2. 38

2.38

2.38

2.54

2.54

2.54

2.71

84.3

186

498

681

774

2,230

5,000

2,410

2,230

6,390

16,100

14,400

13,900

16,100

21,400

27,900

August 16

Gage 

height 

(ft)

18.0

17.4

16.7

17.5

18.4

18.3

17.5

16.0

14.5

13.5

13.2

13.5

14.0

13.6

12.5

11.5

11.0

10.7

10.5

10.5

10.7

11.0

15.0

16.7

Discharge 

(cfs)

30, 200

27, 400

24, 300

27, 900

32, 300

31,900

27, 900

21,400

16, 100

13,200

12, 400

13, 200

14,400

13,400

11,000

9,210

8, 360

7,890

7,580

7, 580

7,890

8,360

17,600

24, 300

August 17

Gage 

height 

(ft)

16. 31

15.8

16.1

17.0

18.0

18. 7

17.8

16.5

15.5

14.5

13.8

13.4

12.8

12.2

11.5

11.0

10.2

10.4

10.0

9.5

3.1

9.8

10.0

9.7

Discharge 

(cfs)

22, 600

20, 600

21,800

25,500

30, 200

34, 000

29, 200

23, 500

19,500

16, 100

13, 900

12, 900

11,500

10, 400

9, 210

8, 360

7, 120

7,430

6,810

6, 110

5, 550

6,530

6,810

6, 390

August 18

Gage 

height 

(ft)

9.3

8.9

8.6

8.2

7.8

7.5

7.2

7.0

6.7

6.5

6.3

6.1

6.0

5.9

5.8

5.8

5.8

5.7

5.7

5.6

5.5

5.5

5.4

5.3

Discharge 

(cfs)

5; 830

5, 280

4,890

4,390

3,900

3,540

3, 220

3,000

2,690

2,510

2, 320

2, 140

2,040

1,960

1,890

1,890

1,890

1,810

1,810

1, 730

1, 660

1, 660

1,580

1,500

Note. --Gage heights to tenths for periods of surging in well.
332 FLOOD OF AUGUST 1950 IN KAUAI

Kawaikoi Stream near Waimea, Kauai

Location. --Lat 22°08'00", long. 159°37'15", at old trail crossing, 12| miles

 northeast of Waimea. Altitude of gage, 3, 420 ft (by barometer).

Drainage area. --4. 1 sq mi.

Gage-height record. --Water-stage recorder graph except for period 6 a.m. 

Aug. 17 to 12 p. m. Aug. 18; graph for this period drawn on basis of recorder graph for Mohihi Stream near Waimea.

Discharge record. --Stage-discharge relation defined by current-meter measurement below 279 cfs (180 mgd) and extended by logarithmic plotting on baris 

of slope-area determination at peak stage. Gage heights used to tenths between 3. 4 and 5.0 ft, hundredths below and tenths above those limits.

Maxima. --August 1950: Discharge, 7> 980 cfs (5, 160 mgd) 12 p. m. Aug. 15

 (gage height, 13. 43 ft).

1909-17, 1919 to July 1950: Gage height, 15. 2 ft Dec. 18, 1916 (discharge not determined).

Mean discharge and runoff, August 15-18, 1950

Day

August 15 

16

Cfs

2,040 

1,930

Day

August 17 

18

Cfs

1, 360 

128

Mean discharge, in cfs, for period .. 1, 360 

Runoff, in inches . ................ 49. 3

Gage height and discharge at indicated time, 1950

Hour

12:30

1

1:30

2

2:30

3

4

5

6

7

8

9

10

11

N

12:30

1

2

3

4

5

6

7

8

9

10

10:30

11

12

August 15

Gage 

height 

(ft)

-

3.25

.

3.15

_

3.09

3.06

3.06

3.11

3.23

3.43

3.88

3.92

6.31

5.91

6.32

6.12

5.16

6.45

8.20

11.94

10.82

11. 11

9.86

10.96

11.12

-

11.74

13.43

Discharge 

(cfs)

-

71.2

_

60.3

_

54.9

52.6

52.6

56.5

68.1

95.9

190

190

1,200

982

1, 200

1,090

634

1,250

2,480

6,080

4,890

5, 210

4, 010

5, 110

5, 210

_

5,860

7, 980

August 16

Gage 

height 

(ft)

-

11.44

_

10.57

_

10.08

9.55

8.50

7.37

7. 13

7.75

6.75

6. 32

5.90

5.45

_

5.13

4.90

4.80

5.59

5.43

5. 30

5.07

5.18

5.61

7.90

8. 92

7.55

6.95

Discharge 

(cfs)

-

5,540

_

4,670

_

4, 190

3,730

2,710

1,870

1,690

2, 170

1,500

1, 200

982

727

_

588

511

472

820

727

681

588

634

820

2,240

3,080

2,010

1,620

August 17

Gage 

leight 

(ft)

6.58

7.40

9.02

7.95

7.44

7.85

8.85

10.82

8.65

7.78

7.05

6.60

6.20

5. 90

5.60

_

5.35

5. 15

5.00

4.85

4.75

4.65

4.75

5. 10

5.80

5.05

_

4.65

4.40

Discharge 

(cfs)

1, 380

1,870

3, 170

2,320

1,870

2, 170

2,990

4,890

2,800

2, 170

1, 620

1,380

1, 140

982

820

_

727

634

549

492

455

421

455

588

928

549

_

421

342

August 18

Gage 

height 

(ft)

-

4.25

-

4.12

-

4.00

3.90

3.81

3.74

3.68

3.63

3.57

3.52

3.47

3.43

_

3.40

3.39

3.37

3.35

3.33

3.32

3.31

3.29

3. 27

3.26

-

3.25

3.24

Discharge 

(cfs)

-

296

-

249

-

218

190

166

155

144

135

118

108

104

95.9

_

91.3

89.7

86.6

83.6

82.0

80.5

78.9

75.8

74.3

72.7

-

71.2

69. 6
STAGES AND DISCHARGES AT STREAM-GAGING STATIONS 333

Mohihi Stream near Waimea, Kauai

Location. --Lat 22°07'05", long. 159C36'15", at upper trail crossing, 3. 8 miles 

northeast of confluence of Waiahulu and Poomao Streams, and 12 miles northeast of Waimea. Altitude of gage, 3, 350 ft (from topographic map).

Drainage area. --1. 6 sq mi.

Gage-height record. --Water-stage recorder graph.

Discharge record. --Stage-discharge relation defined by current-meter measurements below 32 cfs (21mgd) and extended to peak stage by logarithmic 

plotting. Gage heights used to half-tenths between 2. 3 and 5. 0 ft, hundredths below and tenths above those limits.

Maxima. --August 1950: Discharge, 1, 930 cfs (1, 250 mgd) 11:30 p. m. Aug. 15, 

1950 (gage height, 7. 23 ft).

1920-26, 1936 to July 1950: Discharge, 1, 420 cfs (915 mgd) Oct. 2,1940 

(gage height, 6. 40 ft, from floodmarks), from rating curve extended above 

32 cfs by logarithmic plotting.

Mean discharge and runoff, August 15-18, 1950

Day

August 15 

16

Cfs

463 

457

Day

August 17 

18

Cfs

435 

48.6

Mean discharge, in cfs, for period . . 351 

Runoff, in inches .................. 32. 6

Gage height and discharge at indicated time, 1950

Hour

1

2

3

4

5

5:30

6

7

8

9

10

11

N

1

2

3

4

5

6

7

8

9

10

11

11:30

12

August 15

Gage 

height 

(ft)

2. 20

2.12

2.08

2.06

2.05

-

2.25

2.49

2.45

2.49

2.70

3. 10

3.72

3.89

3.62

4.35

5.70

6.00

5.60

5.40

5.42

5.52

6. 30

6.80

7.23

7.01

Discharge 

(cfs)

26.3

22.4

20.7

20.0

19.5

-

28.6

41.8

38.7

41.8

55.7

92.6

187

232

167

364

1,010

1, 170

952.

843

843

897

1,350

1,670

1,930

1,790

August 16

Gage 

. height 

(ft)

5.90

5.62

5.89

5.60

5.00

-

4.50

4.28

4.20

3.98

3.92

4.15

3.84

3.64

3.55

3.55

3.62

3.60

3.51

3.53

3.73

3.86

5.00

5.20

_

4.95

Discharge 

(cfs)

1,110

952

1,110

952

631

_

415

347

316

257

232

300

220

176

158

158

167

167

149

158

198

220

631

735

_

607

1 August 17

Gage 

height 

(ft)

5.20

5.10

5.25

6.32

&12

6.54

5.80

5.20

4.85

4.52

4.25

4.05

3.90

3.75

3.61

3.49

3. 38

3.29

3.25

3.32

3.43

3.59

3.48

3.37

_

3. 25

Discharge 

(cfs)

735

681

735

1,350

1,230

1,480

1,060

735

559

415

331

271

232

198

167

149

133

119

111

119

141

167

149

127

_

111

August 18

Gage 

height 

(ft)

3. 13

3.02

2.94

2.85

2.79

_

2.73

2.68

2.63

2.58

2.55

2.51

2.48

2.45

2.43

2.40

2.38

2.35

2.33

2.31

2.28

2.26

2.24

2.22

_

2. 20

Discharge 

(cfs)

99.0

82.0

77.4

68.1

63.4

_

59.6

55.7

51.8

48.0

44. 9

41.8

41.8

38.7

38.7

36.4

36.4

34.0

34.0

30.9

30.9

29.1

28.2

. 27. 2

_

26.3
334 FLOOD OF AUGUST 1950 IN I^AUAI

Makaweli River near Waimea, Kauai

Location. --Lat 21°58'15.", long. 159°38'55",0.7 miles upstream from confluence 

with Waimea River, 1.9 miles northwest of Waimea, and 3.8 miles northwest of 

Makaweli. Altitude of gage, 30 ft (hand levels from estuary at confluence 

with Waimea River).

Drainage area. --25. 0 sq mi.

Gage-height record. --Water-stage recorder graph.

Discharge record. --Stage-discharge relation defined by current-meter measurements below 260 cfs (168 mgd) and extended to peak stage by logarithmic 

plotting on basis of slope-area determination at gage height 9. 46 ft. Gage 

heights used to half-tenths between 2. 1 and 4. 0 ft, hundredths below and 

tenths above those limits.

Maxima. --August 1950: Discharge, 9, 220 cfs (5, 960 mgd) 12:30 a. m. Aug. 17 

(gage height, 9. 82 ft).

1943 to July 1950: Discharge, 11, 900 cfs (7, 700 mgd) Feb. 7, 1949 (gage 

height, 10. 66 ft), from rating curve extended above 260 cfs (168 mgd) by 

logarithmic plotting on basis of slope-area determination at gage height 

9. 46 ft.

Mean discharge and runoff, August 15-18, 1950

Day

August 15 

16

cfs

729 

3,070

Day

August 17 

18

cfs

4, 310 

564

Mean discharge, in cfs, for period . . 2, 170 

Runoff, in inches .................. 12. 9

Gage height and discharge at indicated time, 1950

Hour

12:30

1

1:30

2

3

4

5

5:30

6

7

8

9

10

11

N

12:30

1

2

3

4

5

6

6:30

7

8

9

10

11

11:30

12

August 15

Gage

height 

(ft)

_

1.31

-

1.32

1.47

1. 85

1.78

-

1. 69

1.64

1.59

2.50

3. 74

3. 68

3.55

_

4.43

4.65

4. 28

3.85

3.70

5. 11

-

5.96

5. 20

5.40

5.63

6.05

-

7.87

Discharge 

(cfs)

_

11. 3

-

11.8

20.0

53.4

45.6

-

37. 1

32.5

28.6

149

498

480

424

_

805

928

743

538

480

1,240

-

2,070

1, 320

1,470

1,640

2, 070

-

4,780

August 16

Gage

height 

(ft)

_

7.25

-

6. 15

6.85

8.60

8.97

8.65

9.05

8.66

7.40

6.60

6.45

6.35

7.00

7.95

7.15

6.00

5.50

5.20

5.17

5.00

-

4.75

4.65

4.50

4.54

6.80

_

8.70

Discharge 

(cfs)

_

3,640

_

2, 290

3,060

5, 150

7rf 120

6, 200

7,120

6,420

3,950

2,790

2,540

2,540

3, 340

4,970

3,640

2,070

1,550

1,320

1,320

1, 180

_

1,050

928

866

866

3,060

_

6,420

August 17

Gage 

height 

(ft)

9.82

9.70

9.44

9.64

9. 17

8.90

9.50

9.75

9.55

9. 25

8.48.

7.94

7.80

7.34

7.04

_

6.66

6.32

5.82

5.42

5. 19

4. 95

4.70

5.04

5. 30

5.85

5.60

5.85 '

6.14

5.93

Discharge 

(cfs)

9, 220

8,960

8, 170

8,700

7,640

6, 890

8, 430

9, 220

8,700

7,640

5,990

4,780

4,600

3,790

3,340

_

2, 920

2, 410

1,860

1, 470

1,320

1, 180

990

1, 180

1, 390

1,860

1,640

1,860

2, 180

1,960

August 18

Gage 

height 

(ft)

_

5.34

-

4.83

4.60

4.40

4.24

.

4. 10

3.97

3. 87

3.77

3.67

3. 60

3.54

_

3.48

3.44

3.41

3.40

3.53

3.46

_

3.35

3.27 

3.20

3. 17

3. 13

_

3.08

Discharge 

(cfs)

_

1,390

.

1,050

928

805

696

.

650

580

538

498

461

441

424

_

405

388

371

371

424

388

-

356

326

313

300

300

_

286
STAGES AND DISCHARGES AT STREAM-GAGING STATIONS 335 

Combined flow of Waimea and Makaweli Rivers near Wainrtea, Kauai 

Discharge at indicated time, 1950

Hour

12:30

1

1:30

2

3

4

5

5:30

6

7

8

9

10

11

N

12:30

1

2

3

4

5

6

6:30

7

8

9

10

11

11:30

12

Mean

August 15

Discharge

(cfs)

_

13.5

-

14.2

22.4

55.8

48. 1

-

39.6

35. 0

31.3

233

684

978

1, 100

_

l,58t)

3, 160

3,740

2,950

2,710

7,630

.

18,200

15,700

15,400

17,700

23,500

-

32,700

5,500

August 16

Discharge

(cfs)

_

33,800

_

29,700

27, 400

33,000

39, 100

38, 300

39,000

34, 300

25, 400

.18,900

15,700

14, 900

16,500

18,900

18, 000

15,500

12,600

10,500

9,680

9,070

_

8,630

8,510

8,760

9,230

20,700

-

30,700

20,500

August 17

Discharge

(cfs)

32, 700

31,600

29, 600

29, 300

29, 400

32,400

38, 600

42, 000

42, 700

36, 800

29,500

24, 300

20, 700

17,700

16, 200

_

* 14, 400

12,800

11, 100

9, 830

8,440

8,610

8, 110

7,990

7, 500

7,410

8, 170

8, 670

8,710

8, 350

19, 800

August 18

Discharge

(cfs)

_

7, 200

-

6, 330

5,820

5,200

4,600

-

4, 190

3,800

3,540

3, 190

2, 970

2,760

2,560

_

2, 440

2, 350 ,

2,260

2, 260

2, 310

2,200

-

2, 170

2,060

1,970

1,960

1, 880

-

1, 790

3, 380
o m

3Dmzoc

PD 05 m o

rn H^

Ifl Og§§

. §o

XI

00

0X

Ma

9O

x«XM

00

0* Ok J

o

c -n

"** 3 ~ -

sf i a 2

*S f r 2

«

o 3. 3 x e 

a| 8 f

5^ ! -

cog U)

If S

8- 5
FLOOD OF AUGUST 1950 IN KAUAI 337 

SUMMARY OF FLOOD DATA

Flood stages and discharges

Table 1 summarizes the maximum flood stages and discharges 

given in the preceding section of this report. It gives also the maximum stages and discharges for the gaging stations on the island of 

Kauai outside the Waimea River basin, thereby providing a summary 

for all currently operated gaging stations on the principal rivers and 

streams on Kauai. The map reference numbers on this table are 

applicable to figure 46.

Figure 48 shows the flood discharges, in second-feet per square 

mile, which are listed in table 1, plotted against the corresponding 

drainage areas.

Annual floods in Waimea River

In addition to detailed information on a specific flood, the engineer 

is interested in the relative magnitude of the flood with respect to 

other floods that are known to have occurred at the same point. Table 

2 lists the annual floods in Waimea River. Records prior to the fiscal 

year 1940-41 have been revised on the basis of tests of a model of the 

station site.
Table 1. --Summary of flood stages and discharges in Kauai, T. H., in August 1950

[Maximum discharges for flood of August 1950 were obtained from gaging-station records except as otherwise indicated by the

following symbols: M, model study; S, slope-area determination]

No. 

on 

fig. 46

1

2

3

4

5

6

7

Stream and place 

of determination

Wdimea River below Kekaha ditch

intake, nearWaimea

Waimea River 

near Waimea

Waimea River 

makai at Waimea

Kawaikoi Stream 

near Waimea

dMohihi Stream 

near Waimea

Waiahulu Stream

near Waimea*

Makaweli River 

near Waimea

Drainage 

area 

(sq mi)

45.0

57.8

88.0

4.1

1.6

20.0

25.0

Period 

of 

record

1921-50

1910-19 

1943-50

1943-50

1909-17 

1919-50

e!909-12 

1920-26 

1936-50

1916

1917-18 

1925-50

1943-50

Maximum previously known '

Date

Feb. 7,

1949

Feb. 7, 

1949

Feb. 7, 

1949

Dec. 18, 

1916

Oct. 2, 

1940

Feb. 7,

1949

Feb. 7, 

1949

Gage 

height 

(ft)

24. 2

19.3

11.40

15.2

6.40

17.0

10.66

Discharge 

(cfs) .

27, 900

37, 100

(b)

(c)

1,420

24, 800

11,900

Cfs 

per 

sq mi

620

642

-

-

888

1,240

476

Maximum during present flood

Date 

and 

hour

Aug. 17

Aug. 17 

6 a.m.

Aug. 17, 

6 a.m.

Aug. 15, 

12 m.

Aug. 15, 

11:30 p. m.

Aug. 17

Aug. 17, 

12:30 a. m.

Gage 

height 

(ft)

a 25

al8.7

7.50

13.43

7.23

a!8.3

a9. 82

Discharge 

(cfs)

30, 900M

34, OOOS

(b)

7, 980S

1,930

28, 000

9, 220S

Cfs 

per 

sq mi

687

588

-

1,950

1,210

1,400

369
Hanapepe River at 

Koula, near Eleele

Hanapepe River 

at Hanapepe

South Fork Wailua

River near Lihue

North Fork Wailua

River at altitude

650 ft, near Lihue

East Branch of 

North Fork Wailua 

River near Lihue

Kapaa River at 

Kapahi ditch intake, 

near Kapaa

Anahola River near 

Kealia

18.8

26.9

22.4

6.6

6.2 

3.3

5.5

1917-21 

1926-50

1949-50

f!911-50

g!910-50

1912-50

U910-15 

J1913-20 

1936-50

1912-50

Dec. 17, 

1949

Dec. 17, 

1949

Jan. 16,

1920

June 2,

1943

Dec. 24, 

1927

Feb. 7, 

1949

Apr. 1, 

1948

11.73

6.58

11.25

h9.96

10.57 

4.65

11.06

16, 100

(b)

44, 900

6,220

5,170 

5,520

12, 300

856

-

2,000

942

834 

1,670

2,240

Aug. 16, 

5 a. m.

Au3. 16. 

6 a. m.

Aug. 16

Aug. 16

Aug. 16, 

6 a. m.

Aug. 15, 

4:30 p. m.

Aug. 15, 

4:30 p. m.

8.90

4.55

alO. 6

all. 85

5.79 

2.72

4.83

9. 110M

(b)

15, 900M

6, 030M

1, 020M 

1,520

1,350

485

-

710 %

I

>

914 3

O

164 r

8O 

461 g

245

10

11

12

13

14

a Faulty or no gage-height record; maximum stage from floodmarks. 

b This station is for collection of gage-height record only. 

c Discharge not determined.

d Formerly published as Mohihi Stream at altitude 3, 500 ft, near Waimea. 

e Fragmentary record at site 2 mi downstream.

f December 1911 to November 1918 at site and third of a mi upstream.

g December 1910 to September 1914 at site 300 ft downstream from confluence of main and east branches; records not equivalent. 

h Datum then in use.

i At site half a mile upstream, published as Kapaa River at Kapaa. 

j At site three-quarters of a mile upstream, published as Kapaa River near Kealia. 

* This gaging station, although published as on Waiahulu Stream, is on Waimea River, 

Poomao Streams.

formed by the confluence of Waiahulu and
Table 1. --Summary of flood stages and discharges in Kauai, T. H., in August 1950--Continued

No. 

on 

fig,46

15

16

17

18

Stream and place 

of determination

Hanalei River at

altitude 625 ft, 

near Hanalei

Hanakapiai Stream 

near Hanalei

Hanakoa Stream 

near Hanalei

Kalalau Stream

near Hanalei

Drainage 

area 

(sq mi)

7.4

2.6

1. 1

1.6

Period 

of 

record

1914-50

1931-50

1931-50

1931-50

Maximum previously known

Date

Apr. 1, 

1948

Dec. 23, 

1937

Dec. 21, 

1946

Feb. 7.

1949

Gage 

height 

(ft)

11.20

8.41

5.98

4. 46

Discharge 

(cfs)

21, 400

4, 150

1,060

959

Cfs 

per 

sq mi

2,890

1,600

964

599

Maximum during present flood

Date 

and 

hour

Aug. 17, 

1 a. m.

Aug. 17, 

1:30 a. m.

Aug. 16, 

10 p. m.

Gage 

height 

(ft)

6.82

6.93

7.29

Discharge 

(cfs)

4,800

2,520

1,730

Cfs 

per 

sq mi

649

968

1,570
SUMMARY OF FLOOD DATA 341 

Table 2. --Annual floods in Waimea River, for years ending June 30, 1922-51

Calendar

year

1922

1923

1923

1925

1925

1927

1927

1928

1930

1930

1931

1932

1933

1935

1935

1937

1938

1939

1940

1940

1942

1942

1943

1945

1945

1946

1947

1949

1950

1950

Month

Jan.

.Jan.

Dec.

Mar.

Dec.

Feb.

Dec.

Nov.

Feb.

Nov.

Aug.

Nov.

Dec.

Feb.

Dec.

Mar.

Mar.

May

Jan.

Oct.

Feb.

Dec.

Aug.

Apr.

Dec.

Dec.

Dec.

Feb.

Jan.

Aug.

Day

31

10 or 12

23

23

30

15

24

4

27

18

4

18

21

26

9

19

26

11

7

2

19

6

11

6

6

22

17

7

6

17

Waimea River near

Waimea (drainage

area, 57. 8 sq mi)

Gage

height

(ft)

11.45

12.80

13.10

10.79

19. 3

9. 1

18.7

Discharge

(cfs)

10,300

13, 600

14, 400

8,850

37, 100

5,550

34, 000

Waimea River below

Kekaha ditch intake,

near Waimea (drainage area, 45.0 sq mi)

Gage

height

(ft)

ab!5.£5

abl8.47

ab!8. 01

abll.76

ablO. 12

16.20

20.40

16.20

17. 92

14.0

14.90

16.40

15.04

16.64

13.80

15.0

16.95

15.20

15. 12

17.60

13. 22

15.65

15.40

14.80

13.90

16.90

-

24. 2

13.78

25

Discharge

(cfs)

ell, 000

c!5, 800

c!4, 900

c4, 330

c2, 180

ell, 600

c!9, 300

ell, 600

c!4, 700

c7, 890

c9, 420

c!2, 000

c9, 660

c!2, 400

c7, 550

c9, 590

c!2, 900

c9, 930

c9, 790

14, 100

6,560

10,700

10, 300

9,250

7,720

12,800

-

27, 900

7,550

30,900

a Converted to present datum.

b Maximum stage recorded; may be too low owing to faulty intake action.

c Revised.
342 FLOOD OF AUGUST 1950 IN KAUAI 

PHYSICAL FEATURES OF KAUAI

Kauai is the fourth in size of the eight main islands in the Hawaiian 

Archipelego, and lies at the northwest end of the group. The island is 

555 square miles in area," and is approximately circular in outline. 

The central mountain mass gives the island an approximate cone shape. 

The apex of the cone is formed by the two peaks Waialeale and 

Kawaikini, altitudes 5, 080 and 5, 17U feet respectively. Kawaikini, the 

higher, but less well known of the two peaks, is about a mile due south 

of Waialeale, and the connecting ridge is nowhere less than 5, 000 feet 

in altitude. From this central mountain mass, streams radiate in all 

directions.

Kauai is the oldest of the eight principal islands, and because it is 

more maturely dissected than others, its various natural features are 

better differentiated. The valleys are longer, deeper, and broader 

than those of the other Hawaiian islands. The island has luxuriant vegetation owing to abundant rainfall, and it has been properly termed the 

Garden Island.

According to the territorial health department, the population of 

Kauai as of January 1951 was 30,374. The people live in small towns 

and villages, the largest of which are Waimea, Lihue, and Kapaa. The 

island has excellent roads around the perimeter except for a section 

along the northwestern coast where precipitous cliffs drop almost vertically into the Pacific Ocean. That section is known as Na Pali coast 

(in English, The Cliff coast ).

Rainfall varies greatly in different parts of the islands according 

to exposure to trade winds and to elevation above the sea. The average 

annual rainfall along the coast line ranges from 15 inches at Mana, 

which is at the leeward, or western, side of the island, to 45 inches 

at Lihue at the east end, and to 100 inches at Hanalei, which is on the 

windward, or northern, side of the island where the moisture-laden 

trade winds strike first. The increase in rainfall is rapid with increase in elevation. At the summit of Waialeale the maximum annual 

rainfall recorded by the U. S. Geological Survey was 624 inches in 

1948.

The Waimea River basin lies on the leeward side of the island and 

comprises an area of about 58 square miles exclusive of the Makaweli 

River basin. It is the largest river basin on the island. It is shaped 

like a square in its upper part, 7 miles on a side. Almost all the tributary streams rise on the northeastern side at an elevation of 4, 000 

to 5, 000 feet and flow southwestward to the main stream, which flows 

southward in a spectacular canyon 2, 000 to 3, 000 feet deep. This 

Waimea Canyon is especially noteworthy. It is about 10 miles long 

and about a mile wide and in coloring and sculpture it may be compared 

with the Grand Canyon of the Colorado.

The main Waimea is called Poomao River in the upper part of the 

canyon. The chief tributaries from north to south are Kawaikoi,
METEOROLOGICAL FEATURES OP THE FLOOD 343

Waiakoali, Mohihi, Waiahulu, Koaie, Waialae, and Mokihana Streams. 

The northern part of the Waimea basin consists of an open rolling but 

swampy country called the Alakai swamp, which serves to some extent as a natural reservoir, regulating the flow of the streams.

At present gaging stations are operated on Waiahulu, Kawaikoi, 

Mohihi, and Waimea streams in the northern part of the basin, and on 

Waimea River and Makaweli River, which joins the Waimea River lj 

miles above the outlet into the ocean, at the lower portion of the basin.

METEOROLOGICAL FEATURES OF THE FLOOD

Precipitation

The storms that occur in the Hawaiian Islands are generally of two 

types, referred to as trade wind storms and kona storms. The 

source of the trade wind storms is in the North Pacific subtropical 

anticyclone. A characteristic of a trade wind storm is that the total 

rainfall increases with altitude. The projection of the mountains far 

up into the prevailing trade winds is a dominant factor in the production of precipitation over the windward slopes of the islands. Records 

of past storms indicate that the trade wind type does not produce 

floods of such magnitude as the kona type.

The kona storms generally occur during the cooler months of the 

year. They are preceded by strong and persistent southerly winds, 

and are generally produced by frontal advance associated with the 

extratropical cyclones over the North Pacific. The direction of the 

kona storm is generally from southwest, with highest precipitation 

being recorded on the lee side of the mountain ranges.

*

In August 1950 the Hawaiian Islands came under the influence of 

a tropical cyclone of full hurricane force. According to the U. S. 

Weather Bureau this was the first instance in 45 years of meteorological records in this area that a storm of such intensity had approached so close to the islands. Inasmuch as this was the first 

Hawaiian hurricane, it was designated as Able , or, in the 

Hawaiian language, Hiki

Isohyetal lines shown on the map (fig.46) were based on all available rainfall records. Most of the gages were located in relatively 

low-lying areas and permitted the plotting of ishoyetal lines with a 

satisfactory degree of accuracy in these districts. The rain gages 

located in the area of greatest rainfall are read at bi-monthly intervals, however, but fortunately were read a short time before 

the storm. Thus the amount read after the hurricane could all be 

attributed to the precipitation due to the storm.

Rainfall records collected froA the rain gages in the Waimea 

basin are presented in table 3. The gage at the ranger station at
344 FLOOD OF AUGUST 1950 IN KAUAI

Kokee is read daily, and the installation at Waialeale is a continuous 

recorder. Their records afford some hint as to the daily precipitation 

at the other gages, which give only the total rainfall for the storm.

Table 3. -- Daily precipitation, in inches, August 14-19, 1950 

f Data published by the U. S. Weather Bureau]

No.

on

fig. 46

1

2

3

4

5

6

7

Altlr

Rain gage tude

(ft)

Kanalo Huluhuhu

Ranger Station,

Kokee 3, 600

Kilohana 4, 023

Mohihi Crossing 3, 500

Mohihi Divide 3, 920

Paukahana 3, 723

Waiakoali 3, 450

Waialeale 5, 080

A UG U S T

14

1.80

15

9.13

7.65

16

28.62

8.45

17

12.23

13.05

18

2.36

0.90

19

0.10

Total

52.34

a60

41.4

32. 4

38.5

43. 9

31. 95

a Estimated

Meteorology 

By R. H. Simpson, United States Weather Bureau

The Hawaiian hurricane Hiki was first detected on the charts at 

the Honolulu Airpost during the night of August 13. It moved into the 

Hawaiian area from the vast expanse of ocean southeast of the islands, 

from which reports are rarely available and about the meteorology of 

which little is known. Such data as have been available in previous 

years indicate that the intertropical convergence zone between 120° 

and 168° west longitude normally does not advance far poleward into 

the summer hemisphere. Hence, the trade winds of the northern and 

southern hemispheres rarely converge at large angles, the shift frequently being only from east-northeast to east-southeast.

Scattered reports from ships in the area during the summer of 

1950 had on several occasions shown the intertropical convergence 

zone to be farther north than usual with a westerly flow as far north 

as the 10th parallel--conditions favorable for the development of tropical cyclones. The research ship-*Horizon"encountered these westerlies near the 145th meridian, south of the region where Hiki probably 

formed, at approximately the time of the storm's inception. Figure 

49shows the progress of the storm from -a point southeast of the 

Hawaiian Islands to a point in the eastern hemisphere where the storm 

had largely spent its force.
Figure 49. --United States Weather Bureau map showing path of hurricane

"Hiki, " August 1950.
346 FLOOD OF AUGUST 1950 IN KAUAI

Hiki arrived east of Hilo an immature storm of very small diameter. Airplane reconnaissance on August 14 estimated the velocity of 

surface winds to be 45 to 50 knots (52 to 58 miles per hour) near the 

center. During the next 24 hours the storm intensified, reaching full 

hurricane force; however, it remained of small diameter, and winds 

of gale force extended outward less than 150 miles. The northwest 

movement of the hurricane became blocked temporarily on August 17 

as a high pressure ridge west of the Hawaiian Islands intensified. 

During the next 24 hours the hurricane was forced slowly southward, 

seemingly poised between lower troposphere currents, which would 

have carried it farther westward, and higher-level westerlies, which 

tended to carry it northeastward. At this stage an airplane reconnaissance reported winds up to 90 miles per hour just south of the 

storm center, and it became necessary to alert the populations of Kauai 

and Oahu against possible loop movement of the hurricane, which would 

have carried it east and northeastward through the Kauai channel.

Fortunately the blocking action to the west eased and Hiki resumed 

its westward movement, passing south of French Frigate Shoal and 

Midway Island before it began its curvature near 170° in the eastern 

hemisphere.

Distinguishing features of Hiki's curvature were that the movement 

of the hurricane was not accelerated and that, as colder air circulated 

into its lower vortex from the north on August 29 and 30, it came 

virtually to a standstill and filled rapidly. Ships reporting near the 

storm center at that time indicated that the maximum winds diminished 

there from more than 85 miles per hour to less than gale force.

The eye of the storm was entered by two reconnaissance planes and 

several ships. It was described as being 20 to 25 miles in diameter, 

overcast, with lowest pressure 29. 00 inches.

As all of Hawaii remained in the southern or less dangerous semicircle of the hurricane, Hiki caused little wind damage. The highest 

sustained winds reported were 68 miles per hour at Kilauea, Kauai; 

50 miles per hour on the island of Niihau; and 48 miles per hour at 

Lanai airport on the island of Lanai. The roofs of several houses 

were blown off, and unbraced masonry walls of one house under construction were blown over. One life was lost at Kohala, Hawaii, by 

electrocution through contact with a live wire blown down by strong 

winds. The greatest damage resulted from flooding of the Waimea 

River on Kauai, where more than 200 residents had to be evacuated.

Hurricane Hiki differs from kona storms in that Hiki had most of 

its energy concentrated around a small center, whereas kona storms 

generally have their energy spread over much larger areas. Mechanically the two storms are quite different. The kona storms depend upon cool air for sustenance whereas tropical cyclones such as 

Hiki depend upon uniformly warm moist air. Upper air currents of 

the average kona storms are nestled.in p.ools of cold air, whereas 

tropical cyclones like hurricane Hiki may be described as pools of
METEOROLOGICAL FEATURES OF THE FLOOD 347

warm air. Both types of storm, however, produce cloudy and very 

rainy weather and also humid and depressive conditions near the surface.

Tropical cyclones of the eastern Pacific are called hurricanes, 

while in the western Pacific they are known as typhoons . In the 

south Pacific tropical cyclones are generally called hurricanes; near 

Australia they are sometimes called willy-willys ; in the Phillipines 

they are called baguios ; and in the Indian Ocean near India they are 

sometimes called Bay of Bengal cyclones. In the Atlantic they are 

known as hurricanes. Actually they are the same phenomenon and the 

difference in nomenclature is only a geographical one.

INDEX

Page 

Combined flow of Waimea and Makaweli

Rivers near Waimea, Kauai ............ 335

Floods, annual, in Waimea River ......337,- 341

Flood data, summary of...... ............ 337

Flood stages and discharges .............. 337

Flood stages and discharges,

summary of ....................... .338 - 340

Introduction............................. 327

Kawaikoi Stream near Waimea, Kauai ..... 332

Makaweli River near Waimea, Kauai ...... 334

Meteorology ......................... .344 - 347

Meteorological features of the flood ... .343 - 347

Mohihi Stream near Waimea, Kauai ....... 333

Physical features of Kauai ............ .342 - 343

Precipitation ........................343 - 344

Stages and discharges at stream gaging

stations ........................... 327

Waimea River near Waimea .............. 331

349

U. S. GOVERNMENT PRINTING OFFICE : O 1952