Floods of April 28, 1966 In the Northern Part of Dallas, TexasThe floods of April 28, 1966, in the...

Floods of April 28, 1966 In the Northern Part of Dallas, Texas

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1870-B

Prepared in cooperation with the city of Dallas

Floods of April 28, 1966 In the Northern Part of Dallas, TexasBy WILLARD B. MILLS and ELMER E. SCHROEDER

FLOODS OF 1966 IN THE UNITED STATES

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1870-B

Prepared in cooperation with the city of Dallas

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969

UNITED STATES DEPARTMENT OF THE INTERIOR

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY

William T. Pecora, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402

CONTENTS

PageAbstract___ _____________________________________________________ BlIntroduction. _____________________________________________________ 1Acknowledgments _________________________________________________ 2The study area__________________________________________________ 2Flood history.____________________________________________________ 11Rainfall____________________________________________________ 12

Antecedent rainfall_____________________________________________ 12Rainfall on April 28, 1966__________________________________ 12

General description of the April 28, 1966, flood______________________ 19Inundation _______________________________________________________ 22Flood damage.____________________________________________________ 23Determination of flood discharge.___________________________________ 23Summary_ _ ______________________________________________________ 24Streamflow data.___-________-____-______-__-______-_______-_-_---- 27

Explanation of data._________________________________________ 27Station data._________________________________________________ 29

Joes Creek at Walnut Hill Lane, Dallas, Tex______________.___ 29Joes Creek at State Highway 114, Dallas, Tex ________________ 29Bachman Branch at Walnut Hill Lane, Dallas, Tex____________ 30Slaughter Branch at Walnut Hill Lane, Dallas, Tex____________ 30Bachman Branch at Northwest Highway, Dallas, Tex__________ 30Bachman Branch at Midway Road, Dallas, Tex_______________ 31Bachman Branch at Webbs Chapel Road, Dallas, Tex_________ 31Bachman Branch at Bachman Lake, Dallas, Tex______________ 31Turtle Creek below McFarlin Boulevard, Dallas, Tex__________ 32Turtle Creek at Dallas, Tex___._______________.____-_-_.-- 32White Rock Creek at Keller Springs Road, Dallas, Tex_ _______ 32Spanky Branch at McCallum Lane, Dallas, Tex___-_________-- 33Armstrong Branch at Melrose Drive, Richardson, Tex_________ 33Cottonwood Creek at Forest Lane, Dallas, Tex-______-----___. 34Floyd Branch at Valley View Road, Dallas, Tex__ _ ____________ 34Floyd Branch at Forest Lane, Dallas, Tex____________________ 34White Rock Creek at Greenville Avenue, Dallas, Tex__________ 34White Rock Creek at White Rock Lake, Dallas, Tex_________ 35Ash Creek at Highland Drive, Dallas, Tex_ _ ________________ 35Forney Creek at Lawnview Avenue, Dallas, Tex_____________ 36White Rock Creek at Scyene Road, Dallas, Tex_____________ 36

Selected references.._______________________________________________ 37

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IV CONTENTS

ILLUSTRATIONS

Page PLATE 1. Map showing areas flooded in the north Dallas area,

Texas____________.__________________________ In pocket2. Maps and graphs showing cumulative rainfall at 30-

minute intervals and total rainfall for the storm of April 28, 1966, north Dallas area, Texas________ In pocket

FIGURE 1. Map showing location of watersheds._________________ B32-7. Flood profiles:

2. Joes Creek________________________._________ 53. Bachman Branch.___________________________ 64. Turtle Creek_______________________ 85. Upper White Rock Creek_________________ 96. Cottonwood Creek___________________________ 107. Floyd Branch-_________-_.______________ 13

8. Graph showing accumulated rainfall, April 13-28, 1966,at rain gage 6-W_______.__-____________._________ 14

9. Graph showing comparison of maximum point rainfall intensity at gage 12-W with the rainfall intensity- duration-frequency curves for Dallas.____-.__.__ 15

10-12. Graphs showing comparison of rainfall intensities on watersheds with the rainfall intensity-duration- frequency curves for Dallas:

10. Bachman Branch watershed._________________ 1611. Joes Creek watershed______________________ 1712. Turtle Creek watershed____________________ 18

13. Rainfall-runoff hydrographs for storm on Joes Creekand Bachman Branch watersheds._______________ 19

14. Rainfall-runoff hydrographs for storm on Turtle Creekand White Rock Creek watersheds________________ 21

15-17. Photographs of flood damage:15. Joes Creek at Walnut Hill Lane. _-_-.__ __ _ _ 2316. Bachman Branch___________________________ 2417. Turtle Creek at Fitzhugh Avenue.____________ 25

18. Photograph of flooding on White Rock Creek at ScyeneRoad____________--.-..__________.____ 26

TABLE

Page TABLE 1. Flood stages and discharges ______________________ B28

FLOODS OF 1966 IN THE UNITED STATES

FLOODS OF APRIL 28, 1966, IN THE NORTHERN PART OF DALLAS, TEXAS

By WILLARD B. MILLS AND ELMER E. SCHRQEDER

ABSTRACT

The floods of April 28, 1966, in the northern part of Dallas, Tex., caused heavy damage to a relatively small area. Flood damage was estimated at $2,500,000; and of this amount, $1,330,000 damage was along Bachman Branch, which has a drainage area of 12.3 square miles. At least seven persons died as a direct result of the floodwaters.

The flood was caused by a 5-hour storm in the early hours of April 28. Antece dent rainfall had so saturated the area that the intense, but relatively low, total rainfall (less than a 50-year return period) caused historical floods to be exceeded at many points. A peak runoff rate of 3,160 cubic feet per second per square mile occurred on a 1.5 square-mile area within the watershed.

INTRODUCTION

A rainstorm in the northern part of Dallas during the early hours of April 28,1966, produced up to 6.7 inches of rain in a 6-hour period; 4.9 inches of rain fell within 1 hour. The intensity of the rainfall exceeded a 100-year return period by a considerable amount for dura tions of 30 minutes to 2 hours, as indicated by U.S. Weather Bureau Technical Paper 25. Because almost 8 inches of rain had fallen during the preceding 2 weeks, the watershed was well saturated, and all storage areas were full. In addition, most of the area is urbanized. This combination of intense rainfall and other hydrologic conditions favorable to high runoff resulted in flood flows greater at some points than the highest flood flows ever recorded on small streams in Dallas. A peak runoff rate of 3,160 cfs per sq mi (cubic feet per second per square mile) occurred on a 1.5 square mile area. This is the second highest peak rate of runoff per square mile recorded by the U.S. Geological Survey in Texas. The highest peak runoff rate recorded, 3,350 cfs per sq mi, occurred on June 30, 1936, on the 4.12 square mile drainage area of Bunton Branch near Kyle, 20 miles southwest of Austin.

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B2 FLOODS OF 1966 IN THE UNITED STATES

Flood damage in Dallas was extensive. Bridges were washed away; more than 270 homes and at least 40 businesses were severely damaged; lawns, gardens, and cemeteries were inundated; and seven lives were lost. Flooding on Bachman Branch, one of the watersheds in north Dallas, caused damages estimated at $1,330,000.

This report describes the flood event of April 28, 1966, for the fol lowing watersheds in north Dallas: Joes Creek, Bachman Branch, Turtle Creek, Cottonwood Creek, and Floyd Branch. This flood event is described in terms of rainfall (magnitude, intensity, frequency, and distribution), peak discharge at selected points, flood profiles, inun dated areas, comparison with previous floods, effects of channel changes on flood profiles, and property damage and loss of life due to the flood. The flood on the main stem of White Rock Creek is also described, but in less detail. Figure 1 shows the location of the watersheds, and plate 1 shows the flooded areas.

In August 1961 the U.S. Geological Survey, in cooperation with the city of Dallas, began a program of continuing investigations de signed to evaluate the hydrologic factors affecting floods on several small streams in Dallas. Supporting data and computations are in the files of the U.S. Geological Survey, Water Resources Division, Room 647, Federal Building, 300 East 8th Street, Austin, Tex.

The height of a flood at any location is generally stated in terms of the stage, which is the elevation of the water surface above a se lected datum plane. In this report, flood heights (stages) are expressed in feet above mean sea level.

The rate of flow of a stream is the volume of water that passes a particular point in a given period of time. Discharge rates are given in cubic feet per second. The peak discharge is the maximum instantane ous rate of flow for a given flood.

ACKNOWLEDGMENTS

The aid of personnel from the city of Dallas who furnished data and assistance for this report is gratefully acknowledged. H. H. Stirman, Director of Public Works, Dallas, Tex., and his staff worked closely with the field engineers to aid in collecting the most accurate data. On the morning of April 28, 1966, Public Works crews were in the flood area and flagged highwater marks. These marks were very helpful in establishing elevations for the flood profiles.

THE STUDY AREA

The study area comprises about 150 square miles in or near Dallas. Most of the study area is in the 136-square-mile drainage area of White Rock Creek, a tributary to the Trinity River. Because the storm

APRIL 28, 1966, NORTHERN PART OF DALLAS, TEXAS B3

was centered in the northern part of the city, two subwatersheds, Cotton wood Creek watershed (8.50 sq mi) and Floyd Branch water shed (4.17 sq mi), within the White Eock Creek watershed were studied in detail. The upstream part of these two watersheds is in the city limits of Richardson, north of the Dallas city limits. Three other watersheds Joes Creek, Bachman Branch, and Turtle Creek were investigated in detail.

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Within the reaches subject to extreme flooding, the stream channels are similar in shape and capacity, even though they differ in size. Each channel generally consists of a wide flood plain along both banks in the upper reaches and a relatively narrow flood plain in the lower reaches. As tributaries approach the Trinity River, the flood plain of the Trinity River provides a wide area of overflow. Much of the flood plain is in urban areas and is covered with well-kept lawns and paved streets. The rest of the flood plain is mostly covered with natural grasses on abandoned farmland. The main channels of the major tributaries, which are generally incised to limestone bedrock, are approximate trapezoids cut into the well-compacted alluvial material. Trees and brush growth along both banks of the main channels is fairly heavy. The low-flow channels are in solid limestone and contain some sand and gravel riffles. Little scour occurred except at bridges and constrictions where a large part of the water flowed over the roads. The areas described in this report are in metropolitan Dallas. Each area has a high percentage of impervious cover.

The drainage area of Joes Creek at Interstate Highway 35E is 7.51 square miles. The streambed slopes uniformly from an elevation of 633 feet at the headwater near Valley View Lane to 479 feet at Marsh Lane in a distance of 3.6 miles. In the 3.3 miles below Marsh Lane the streambed slopes uniformly from an elevation of 479 feet to 410 feet at Interstate Highway 35E. Figure 2 shows the profiles of the floods and elevations of the streambed.

The drainage area of Bachman Branch is 12.3 square miles at Bach- man Lake spillway and 12.6 square miles at Interstate Highway 35E. The streambed slopes uniformly from an elevation of 655 feet at the headwaters near Valley View Lane and Preston Road to 474 feet at Brookview Drive in a distance of 4.4 miles. From Brookview Drive the streambed slopes uniformly for 1.2 miles to an elevation of 447 feet at Midway Road. Beyond this point the streambed has a constantly decreasing slope to Bachman Lake, where the spillway elevation is 438.1 feet. Below Bachman Lake the streambed slopes from an eleva tion of 419 feet to 405 feet at Interstate Highway 35E in 0.7 mile.

The dam retaining Bachman Lake was built in 1901 as part of the water-supply system for Dallas. The lake, which covers about 128 acres, is at the lower end of Bachman Branch just above the conflu ence with Elm Fork Trinity River. Floodwater will bypass the spill way and flow around the right end (north side) of the dam when the lake water level exceeds 443 feet in elevation. Figure 3 shows the pro files of the floods and elevations of the streambed.

The drainage area of Turtle Creek is 7.98 square miles at the stream- gaging station 200 feet above Hall Street. The streambed slopes uni formly from an elevation of about 620 feet between Royal Lane and

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Walnut Hill Lane to 541 feet just downstream from Lovers Lane in a distance of about 2.8 miles. In the upper part of this reach the chan nel is concrete lined to Northwood Road. From Northwood Road to below Lovers Lane, the main stream channel consists of two 6- by 4- foot storm sewers. Downstream from Lovers Lane the channel drops uniformly for 3.0 miles to an elevation of 433 feet at Turtle Creek Drive. In the 1.8 miles from Turtle Creek Drive to Harry Hines Boule vard, the streambed drops uniformly 46 feet. Below Lovers Lane the channel consists mainly of a rectified channel interspersed with small dams.

A large-volume pressure storm sewer (278 sq ft in cross-sectional area ranging from 18i/£ ft semieliptical to a 16-ft modified horseshoe) begins at the dam below Cedar Springs Road and ends at the Trinity River. The design capacity at the elevation of the dam crest is 3,600 cf s. Figure 4 shows profile of the flood, elevation of the streambed and the dam sites.

Turtle Creek watershed was completely urbanized before the stream- gaging station was installed. Paved streets, well-kept lawns, and rather expensive homes cover most of the area in the watershed.

White Rock Creek is in the northern and eastern parts of Dallas County. The headwaters of White Rock Creek, a tributary of the Trinity River, are about 10% miles north of the Dallas city boundary. Headwater elevations are about 780 feet. The stream flows southward about 30 miles into White Rock Lake, which has a conservation pool elevation of 458 feet. The stream continues southward from White Rock Lake for 10.3 miles to the Trinity River.

From the northern city boundary of Dallas (mile 27.6) to the Texas and New Orleans Railroad Co. bridge (mile 18.7), the streambed has a nearly uniform slope of about 10 feet per mile. In the 5-mile reach between the railroad bridge and White Rock Lake, the slope decreases from a drop of about 5 feet per mile to about 2 feet per mile.

The streambed slopes from the 458-foot spillway elevation to about 414 feet at Garland Road in a distance of 0.2 mile. Within 0.9 mile the streambed drops another 8 feet. Downstream from Garland Road the streambed slopes uniformly at a rate of 4.4 feet per mile. Figure 5 shows profiles of the floods and elevations of the streambed in upper White Rock Creek.

The drainage area of Cottonwood Creek, a tributary to White Rock Creek that rises 1.3 miles north of Dallas County, is 8.50 square miles at Forest Lane, 0.6 mile upstream from the mouth. The streambed slopes from an elevation of 730 feet 1.5 miles north of Dallas city limits to 564 feet at Belt Line Road in a distance of about 4.6 miles. From this point the streambed slopes uniformly to an elevation of 476 feet at the mouth in a distance of 3.9 miles. Figure 6 shows profile of the flood and elevation of the streambed.

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The flood plain has been developed with residences and parks from Campbell Road to Spring Valley Road. Below Spring Valley Road the flood plain is not as completely developed, and a few areas are cov ered with native grasses, trees, or shrubs.

The drainage area of Floyd Branch, which joins Cottonwood Creek about 0.6 mile upstream from the confluence of Cottonwood Creek with White Rock Creek, is 4.17 square miles at Forrest Lane, 0.3 mile upstream from the mouth. The streambed slopes uniformly from an elevation of 680 feet at the headwaters between Campbell Road and Arapaho Road to an elevation of 565 feet at the low-water crossing in the Restland Memorial Park Cemetery in a distance of about 2.9 miles. From the low-water crossing the streambed slopes uniformly for 1.1 miles to an elevation of 529 feet near the Interstate Highway 635 (LBJ Freeway). From this point the streambed slopes uniformly to an elevation of 489 feet at the mouth in a distance of 1.5 miles. Figure 7 shows the profile of the flood and elevation of the streambed.

Floyd Branch is similar to Cottonwood Creek in development of the flood-plain area. Upstream from Spring Valley Road, commercial and residential building has fairly well covered the flood plain. Down stream from Valley View Road, the area is less developed.

FLOOD HISTORY

Previous investigations have traced the flood history of the study area back to about 1900. At that time the number of flood-recording installations was limited; consequently, much of the information for the early records was obtained by interviewing long-time residents and by reading flood accounts in old publications. This report tabulates these historical floods as recorded in preceding reports, along with pertinent remarks. (See "Notable Flood Events" below.)

NOTABLE FLOOD EVENTS

May 25, 1908_____ Flooding of the Elm Fork Trinity River produced back water and caused severe flooding in the lower reaches of Bachman Branch and Joes Creek. Flood stages in lower reaches exceeded those of the October 8, 1962, flood.

April 25, 1922____ A high intensity rainfall, which followed a wet period, produced unusually high runoff from the Bachman Branch and Joes Creek watersheds. Discharges were almost equal to those of the October 8, 1962, flood.

April 19-20, 1942__ Heavy rainfall produced runoff reported to be the high est since at least 1886 along White Rock Creek.

May 1946_______ Substantial runoff occurred.August 1947 . Substantial runoff occurred.


NOTABLE FLOOD EVENTS Continued

June 1949 __. The city of Richardson reported 11.5 inches of rainfall in a 12-hour period. This area contains the headwaters of Cottonwood Creek and Floyd Branch. Cottonwood Creek at Forest Lane had the highest stage since 1892.

April 26, 1957_____ Substantial runoff occurred.October 1, 1959 _. The highest stage since at least 1903 occurred at the

Turtle Creek streamflow station upstream from Hall Street.

July 27, 1962 _ The greatest flood since 1942 at many points in north Dallas.

October 8,1962____ Prior to April 28, 1966, this was the greatest headwater flood since about 1900 along Bachman Branch and Joes Creek.

September 21, 1964__ Flooding was severe although not recordbreaking in the five watersheds of the study area except in upper White Rock Creek. Flooding in the upper White Rock Creek watershed was the greatest known. The average rain fall for an 8-hour period was nearly 12.5 inches on the upper 29.4 square miles of the watershed, resulting in 11 inches of runoff.

April 28, 1966 _ The greatest known headwater flood on Bachman Branch, Turtle Creek, Cottonwood Creek, and Floyd Branch. Flood history begins about 1900.

RAINFALL

ANTECEDENT RAINFALL

The U.S. Weather Bureau station at Dallas recorded more rain dur ing April 1966 than had been recorded in any month since the record began in 1874. Rain gage 6-W, in the White Eock Creek watershed, near the center of the study area, recorded 12.73 inches of rain during the period April 13-28. Of this amount, 7.95 inches fell prior to the April 28, 1966, storm. Figure 8 shows the accumulated rainfall from seven storms at rain gage 6-W for the period April 13-28,1966, which is typical for the study area. Because of these antecedent-rainfall conditions, which caused the ground to be saturated and all the storage areas to be full, a high percentage of rainfall from almost any storm would have become runoff.

RAINFALL ON APRIL 28, 1966

The rains that caused the floods in Dallas began at about 0030 hours on the 28th of April and ceased at about 0600 hours the same day. During this interval, rainfall was intense for about 1 hour. The maxi mum storm rainfall occurred at rain gage 12-W, where the intensity for a 30-minute period was 6.40 inches per hour, and the hourly total was 4.92 inches. (These totals reflect the most intense rainfall and are

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more than the rainfall shown on plate 2 for 12-W.) Figures 9-12 show the intensity of the rainfall at various sites as compared with the intensity-duration frequency for the period 1914-51 at the Dallas Weather Bureau station (U.S. Weather Bureau, 1955). Figure 9 com pares the rainfall intensity that occurred at gage 12-W with the in tensity-duration-frequency relations developed for Dallas. The 500- year return-period curve was extrapolated, using techniques suggested by U.S. Weather Bureau (1961) in Technical Paper 40. An extrapola tion to this great return period was done to show the relative intensity of the storm at 12-W. Figures 10, 11, and 12 compare the areal weighted rainfall intensity (the intensity that occurred over the en tire watershed at the same time) over Bachman Branch, Joes Creek, and Turtle Creek, respectively, with the intensity-duration-frequency relation for Dallas. The return-period curves were drawn using point rainfall. A correction factor can be determined from the inset in figure 10 for each area. For example, to determine the return period for a 1-hour areal weighted-mean rainfall intensity on a 50-square-mile drainage area, divide the mean intensity by 0.80 and then enter the rainfall intensity-duration charts on the 60-minute line. Note that for Bachman Branch and Joes Creek the areal weighted rainfall inten: sity reached the 50-year return-period line. The figures show that the

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APRIL 28, 1966., NORTHERN PART OF DALLAS, TEXAS B15

intensity was rather constant for the first hour until it reached the maximum-return-period line, and then it followed this line for at least 1 hour. Figure 12 shows a decrease of the rainfall southward, but Turtle Creek experienced a record-breaking flood.

The storm centered on the middle of White Eock Creek watershed. Plate 2 indicates the pattern of rainfall for the first 3 hours of the storm. The individual 30-minute totals are shown for each rain gage

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to indicate the amount of rain that accumulated at each site. Plate 2 also shows the total storm rainfall. Note that the storm traveled slowly downstream. Plate 2 (first 1 hour, 30 minutes) indicates, for example, that the peak intensity occurred at all rain gages north of Eoyal Lane and at none of the rain gages south of this road. This timing would logically increase the peak discharge-rainfall ratio and should account, in part, for the magnitude of the flood.

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FIGURE 10. Comparison of rainfall intensities on Bachman Branch watershed with the rainfall intensity-duration-frequency curves for Dallas.


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FIGTJBE 11. Comparison of rainfall intensities on Joes Creek watershed with the rainfall intensity-duration-frequency curves for Dallas.


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FIGUBE 12. Comparison of rainfall intensities on Turtle Creek watershed with the rainfall intensity-duration-frequency curves for Dallas.

APRIL 28, 1966,, NORTHERN PART OF DALLAS, TEXAS B19

The pattern and amount of rainfall resulted in a flood that exceeded historical floods.

GENERAL DESCRIPTION OF THE APRIL 28, 1966, FLOOD

The weighted-mean rainfall for Joes Creek watershed was 4.86 inches. A point total of 4.45 inches was measured on the upper end of the watershed, and 5.04 inches was measured on the lower end. Rain fell on the entire watershed within 5 minutes after the storm began. The maximum intensity for a 30-minute period was 3.74 inches per hour (fig. 11).

Joes Creek at State Highway 114 had a peak discharge of 6,350 cfs. Eighty-five percent of the 4.86-inch rainfall on the 7.51-square-mile watershed above this site ran off. Figure 13 shows rainfall-runoff

JOES CREEK ATSTATE HIGHWAY 114

(Drainage area, 7.51 square miles)10 i . i i i i 10

BACHMAN BRANCHAT MIDWAY ROAD

(Drainage area, 10.0 square miles)10 i . i i i i 20

9

7

5

4 -

Z< 3

2

1 -

G18 Z

O O

16

14

12 OCDD O

10

< en 8 D

Oi i-

6 z

4 K.

A00 03 06 09 12

TIME, IN HOURS

00 03 06 09 12

TIME, IN HOURSEXPLANATION

Discharge Accumulated rainfall Accumulated runoff

Q 30-minute-interval weighted rainfall

FIGTJEE 13. Rainfall-runoff hydrographs for storm of April 28, 1966, on Creek and Bachman Branch watersheds.

Joes


graphs for the State Highway 114 site. Upstream at Walnut Hill Lane, the peak discharge was 6,530 cfs, or a unit runoff of 1,750 cfs per sq mi from 3.73 square miles. (See pi. 2 for flood-determination points.) Figure 2 shows the April 28 flood profile for Joes Creek, along with a profile of the October 8, 1962, flood. Note that above Merrell Eoad the 1966 flood was lower than the 1962 flood. This is due in part to new bridges and channel rectification. Other measurements of discharge show the April 28, 1966, flood to be equal to or greater than the October 8,1962, flood.

Total rainfall measured on the Bachman Branch watershed was 5.30 inches in the upper part and 5.27 inches in the lower part. The influence of rainfall measurements at points outside the watershed lowered the weighted-mean rainfall for the watershed to 5.17 inches. Eain was falling on the entire watershed within 20 minutes. The maximum intensity for a 30-minute period was 3.86 inches per hour (fig. 10). ^

Peak discharge was determined at six sites in the watershed (pi. 2). The highest measured peak rate of runoff per square mile was 3,160 cfs on Slaughter Branch at Walnut Hill Lane from a drainage area of 1.51 square miles. Bachman Branch at Webbs Chapel Road, with a drainage area of 11.0 square miles, had a peak discharge of 18,200 cfs, or a unit discharge rate of 1,650 cfs per sq mi. Eighty-nine percent of the 5.17-inch rainfall on the 10.0 square mile watershed above Bachman Branch at Midway Eoad ran off. Figure 13 shows rainfall- runoff graphs for the Midway Eoad site. Figure 2 shows the April 28 flood profile for Bachman Branch along with a profile of the October 8, 1962, flood. Note that above Forest Lane the April 28, 1966, flood was lower. This is due to the new bridge at Willow Lane and the channel rectification in the area. Downstream discharge measurements indicate the 1966 flood to be greater than the 1962 flood.

Weighted-mean rainfall on the Turtle Creek watershed was 3.53 inches. Point rainfall totals measured in the Turtle Creek watershed ranged from 2.49 inches on the lower end to 4.78 inches on the upper end. The maximum 30-minute intensity was 3.42 inches per hour (fig. 12). Eain fell on the entire watershed within 15 minutes after the rain began.

The two storm sewers from Northwood Eoad to below Lovers Lane overflowed, and floodwaters ran down the streets. Peak discharge was determined at two sites in this watershed (pi. 2). The maximum measured unit rate of runoff was 2,090 cfs per sq mi at a dam 600 feet below McFarlin Boulevard; drainage area is 2.43 square miles. Ninety- two percent of the 3.53-inch rainfall on the 7.98-square-mile watershed above Turtle Creek at Hall Street ran off. Figure 14 shows rainfall-

APRIL 28, 1966,, NORTHERN PART OF DALLAS, TEXAS B21

runoff graphs for the Hall Street site. Figure 4 shows the April 28 flood profile for Turtle Creek.

Weighted-mean rainfall for the 125-square-mile area above White Eock Creek at Scyene Koad was 4.06 inches. Measured-point rainfall ranged from 2.59 inches on the upper end, to 6.70 inches near the center, to 2.20 inches on the lower end of the watershed. The max imum intensity was recorded and the highest total rainfall for this storm was measured in the White Eock Creek watershed at rain gage 12-W (fig. 9).

Peak discharge was determined at 11 sites (pi. 2). The highest meas ured unit rate of runoff was 2,070 cfs per sq mi from the 8.50-square mile area above Cottonwood Creek at Forest Lane. An almost equal unit discharge of 2,060 cfs per sq mi was determined for the 4.17 square miles above Floyd Branch at Forest Lane. Seventy-six per-

TURTLE CREEK ATHALL STREET

(Drainage area, 7.98 square miles)10

WHITE ROCK ATGREENVILLE AVENUE

(Drainage area, 66.4 square miles)

03 06 09

TIME, IN HOURS

03 06 09

TIME, IN HOURS

12

EXPLANATION- Discharge- Accumulated rainfall------ Accumulated runoff

[] 30-minute-interval weighted rainfall

FIGURE 14. Rainfall-runoff hydrographs for storm of April 28, 1966, on Turtle Creek and White Bock Creek watersheds.

B22 FLOODS OF 196,6 IN THE UNITED STATES

cent of the rainfall on the 29.4-square-mile area above White Eock Creek at Keller Springs Road ran off. Sixty-six percent of the rainfall on the 66.4-square-mile area above White Bock Creek at Greenville Avenue ran off. Figure 14 shows the rainfall-runoff graphs for the Greenville Avenue site.

Figure 5 shows peak stages for White Rock Creek above Northwest Highway (Loop 12) as determined from the network of the crest- stage gages. These peak stages are compared with profiles of other floods. Profiles of the April 28 flood were determined for Cottonwood Creek and Floyd Branch and are shown in figures 6 and 7, respectively.

INUNDATION

Flood plains in five of the watersheds were investigated for inunda tion. Plate 1 shows the area inundated by Joes Creek, Bachman Branch, Turtle Creek, Cottonwood Creek, and Floyd Branch. The map used as a base for plate 1 was prepared in 1958 and, consequently, does not detail the development since that time. New areas have been urban ized; industrial plants have been built; freeways have been con structed ; bridges have been rebuilt; and channels have been rectified. These developments have resulted in filling of the natural flood plain, straightening of the channel, changes in road grade, and addition of impervious cover. Each of these factors influences the magnitude and mode of the peak discharge and the consequent inundation.

Examples of the effect of urban development are shown in figures 2 and 3. Most of the upper Joes Creek channel had been rectified prior to April 28, 1966, and since October 8,1962. As a result the April 28, 1966, peak stages were considerably lower than the October 8, 1962, peak stages in the rectified sections (fig. 2), even though the peak discharges in 1966 were equal to or greater than those in 1962. The bridge at Willow Lane on Bachman Branch had been rebuilt and the channel rectified since the flood of October 8, 1962. Figure 3 indicates the results of the hydraulic improvement at Bachman Branch at Willow Lane. The April 28, 1966, peak was 2 feet lower than the October 8,1962, peak.

There is some uncertainty as to the exact area inundated by overflow from the north end of Bachman Lake Dam. Reportedly, this overflow inundated the area as far north as the Northwest Highway. An investi gation of this area showed that certain parts of it had been under water; however, this could have been due to sheet runoff from local rainfall.


FLOOD DAMAGE

At least seven persons died in Dallas as a direct result of the floodwaters. Early damage estimates in the city were $2,500,000; accord ing to Col. Jack Fickessen, District Engineer, U.S. Army Corps of Engineers. Of this amount, $1,330,000 was damage along Bachman Branch, where homes and businesses were inundated.

The flash flood swept over north Dallas in the early morning hours of April 28, 1966, inundating the low-lying areas and sweeping cars, furniture, small buildings, and other items along with it. At some constricting points the water washed out bridges or removed large parts of the channel banks. Engineers collecting field data 2-3 weeks later found items such as clothing, furniture, garden tools, small tool sheds, and books in the flood plains of the streams. The inundation of many luxurious homes caused especially high flood damage. Figures 15-18 show some results of the flood.

DETERMINATION OF FLOOD DISCHARGE

The standard method used by the Geological Survey to determine discharge at a gaging station is to develop a stage-discharge relation from current-meter discharge measurements made at various stages

FIGURE 15. Flood damage on Joes Creek at Walnut Hill Lane.


and then to apply this relation to records of stage. The record of stage is generally obtained from a water-stage-recorder installation that provides a continuous graphic or punch-tape record of stage. The re liability of the stage-discharge relation depends upon how adequately the discharge measurements define the entire range in stage.

Current-meter measurements at or near the time of peak discharge at the gaging stations were impossible to obtain because the flood of April 28, 1966, was of short duration and occurred during the night.

Indirect determinations of peak discharge were made at sites shown on plate 1. These peak discharges were obtained by slope-area, con tracted-opening, culvert, or other types of indirect discharge measure ments. These indirect measurements are based on field surveys of highwater profiles, channel geometry, and hydraulic-structure geometry and are computed in accordance with established hydraulic principles. They are indirect only because the data were collected subsequent to the passage of the flood.

SUMMARY

1. The floods of April 28,1966, were the result of a combination of theevents and conditions, as follows:

a. The rain fell at the same intensity for about 1 hour (figs. 9-12). The gage (12-W) that recorded 6.7 inches in 6 hours and 4.92 inches in a 1-hour period also recorded rainfall intensities for durations of 30 minutes-2 hours that exceeded a 100-year return period by a considerable amount (fig. 9).

FIGURE 16. Flood damage on Bachman Branch. Peak marks can be seen on cur tains. Photograph by Dallas Morning News.


FIGUEE 17. Flood damage on Turtle Creek at Fitzhugh Avenue. Photograph byDallas Morning News.


FIGURE 18. Flooding on White Rock Creek at Scyene Road. Photograph byDallas Morning News,


b. Seven storms had occurred in the preceding 2 weeks, leaving the ground well saturated and the storage areas full.

c. The watersheds are extensively urbanized and therefore con tain a large amount of impervious cover.

2. Floods exceeded historical floods on Joes Creek, Bachman Branch, Turtle Creek, Cottonwood Creek, and Floyd Branch. (Flood his tory at some sites dates as far back as 1892.)

3. The second highest peak-runoff rate per square mile ever measured in Texas occurred on Slaughter Branch at Walnut Hill Eoad, where 4,770 cfs ran off from an area of 1.51 square miles (3,160 cfs per sq mi). This peak rate of runoff is second only to the 3,350 cfs per sq mi that occurred on Bunton Branch on June 30, 1936, from an area of 4.12 square miles.

4. A high percentage of the rainfall ran off each watershed. Joes Creek had 81 percent runoff, Bachman Branch had 89 percent, and Turtle Creek had 92 percent.

STREAMFLOW DATA

EXPLANATION OF DATA

Maximum stages and discharges at the continuous-record gaging stations, crest-stage partial-record stations, and miscellaneous sites are summarized in table 1. The derivation of the maximum data is explained in the station descriptions for each site in the "Station Data" section of this report. The peak-discharge values given in table 1 are for flow as it passed the gaging station or measuring site. Under the heading "Maximum Flood Prior to April 28,1966," the maximum historical flood is given.

Peak discharges, in cubic feet per second per square mile, were computed for all sites.

Following table 1, additional data are presented for each station where streamflow information was collected by the Geological Survey during the April 28, 1966, flood. In general, the information for each continuous-record gaging station is as follows: A description of the station, and a tabulation of stages and discharges at selected times during the day of April 28,1966. For the miscellaneous sites and crest- stage partial-record stations, only the station description is presented, because no information other than maximum stages and discharges is available.


TABLE 1. Flood stages and discharges, flood of April 28, 1966, in Dallas, Texas

Maximum floods

Map Permanent Stream and place No. station of determination

(pi. 1) No.

Drainage area

(sqmi)

Joes Creek

1

2 8-0566.0Hill Lane.

Joes Creek at State Highway 114.

3.73

7.51

Prior to April 28, 1966

Period

watershed

1962-66

1904-66

Year

1962

1908 1962

April ] 1966

28

28

Elevation (ft)

i 478.1 475.2

3431 425.3 426.4

. Discharge

Cfs

(2) 6,530

7,430 6,350

Cfs per sq. mi.

1,750

985 846

Bachman Branch watershed

3 .

4 .

5 .

6

7 .

8 .

8-0567.0

Bachman Branch at Walnut Hill Lane.

Slaughter Branch at Walnut Hill Lane.

Bachman Branch at Northwest Highway.

Bachman Branch at Midway Road.

Bachman Branch at Webbs Chapel Road.

Bachman Branch at Bachman Lake.

4.73

1.51

9.29

10.0

11.0 .

12.3 .

Turtle Creek

9 .

10

11

12

13-

14

15 .

16

17

18

19

20

21

8-0565.0

8-0571.0

8-0571.2"

8-0571.4

8-0571.6

8-0672.0

8-0573.0

8-0573.2

8-0573.4

8-0574.0

Turtle Creek below McFarlin Boulevard.

Turtle Creek at Hall Street.

White

White Rock Creek at Seller Springs Road.

Spanky Branch at McCallum Lane

Armstrong Branch at Melrose Avenue, Richardson, Tex.

Cottonwood Creek at Forest Lane.

Floyd Branch at Valley View Road.

Floyd Branch at Forest Lane.

White Rock Creek at Greenville Avenue.

White Rock Creek at White Rock Lake.

Ash Creek at High land Drive.

Forney Creek at Lawnview Avenue.

White Rock Creek at Scyene Road.

o 40

7.98

1962-66

1962-66

1900-66

watershed

1903-66

1962

1962

1962

1959

2828

28

28 28

28

28

28

1512.8 511.0 530.8

479.9 484.2 466.6 467.97 446.68

444.6

530.9

436.23 438.67

6,160 10,400 4,770

8,530 14,400 9,200

16,000 18,200

15,000

5,080

4,660 12,200

1,300 2,200 3,160

918 1,550

920 1,600 1,660

1,200

2,090

583 1,500

Rock Creek watershed

29.4

6.77

1.06 .

8.50

3.18

4.17

66.4

100

6.92

1.84

125

1886-1966

1917-66

1892-1966

1962-66

1909-66

1886-1966

1910-66

1963-66

1963-66

1886-1966

1964

1964

1949 1962

1962

1949

1964

1964

1963

1963

1908 1964

28

2828

28

28

28

28

28

28

28

28

574.51 565.60

572.02 669.3 631.60

512.5 511. 74 512.32 640.18 647.0 513.7 514. 19 490.43 489.47 465.60 463.82 430.99 431.54 431.36 435.42

3409.2

402.99

37,900 9,020

7,870 5,000 1,290

(») 17,400 17,600 4,030 6,170 (»)

8,590 38,100 27,000 28,300 18,800 «

5,180 «

1,090"36,"206"

21,600

1,290 307

1,160 739

1,220

2,050 2,070 1,270 1,940

2,060 574 407 283 188

749

592"""242

172

1 Peak elevation not comparable with that of April 8,1966, because of subsequent channel rectification.8 Not determined.3 Affected by backwater from the Trinity River.


The station description gives the following information: Location of the gage; size of drainage basin area above the gage; nature of the gage-height record obtained during the period discussed in this report; datum of the gage; definition of the stage-discharge relation; maxi mum stage and discharge during the April 28, 1966, flood; previous maximum during the period of station operation; and available maximum data for floods outside the period of station operation, as indicated from interviews with local residents and from reading his torical documents.

The tables of stage and discharge at selected times where such de tailed definition is warranted are given after the station description. Enough detail is presented so that hydrographs for the flood period can be accurately constructed.

STATION DATA

JOES CREEK AT WALNUT HILL LANE, DALLAS, TEX. (Miscellaneous site)

Location. Lat 32°52'50" N., long 96°51'38" W., at culvert on Walnut HillLane, Dallas, Dallas County, 2.6 miles upstream from Interstate Highway 35B.

Drainage area. 3.73 sq mi. Elevation record. From floodmarks. Datum is mean sea level, datum of 1929,

supplementary adjustment of 1953. Discharge record. Maximum discharge by computation of flow through culvert

and over road. Maximums. April 28, 1966: Discharge, 6,530 cfs (elev, 475.2 ft).

1962 to April 28, 1966: Elevation, 478.1 ft Oct. 8, 1962. Remarks. Road at both ends of the bridge was raised and the channel rectified

for about 2,000 ft downstream since the Oct. 8,1962 flood.

8-556. JOES CREEK AT STATE HIGHWAY 114, DALLAS, TEX.

Location. Lat 32°51'33" N., long 96°53'00" W., at bridge on State Highway 114, 0.9 mile above mouth, 7.8 miles northeast of Dallas County Courthouse in Dallas.

Drainage area. 7.51 sq mi.Elevation record. SR (stage-rainfall) recorder graph, outside peak marks, and

outside staff-gage readings. Datum of gage is mean sea level, datum of 1929, supplementary adjustment of 1953.

Discharge record. Stage-discharge relation defined by current-meter measure ments below 730 cfs and by contracted-opening measurements at 3,300 and 6,350 cfs.

Maximums April 28, 1966: Discharge, 6,350 cfs 0300 hours (elev, 426.4 ft).1962 to April 28, 1966: Discharge, 7,430 cfs Oct. 8, 1962 (elev, 425.3 ft, from

floodmarks).Since at least 1904: Discharge, that of Oct. 8,1962; elevation: 431 ft in 1908;

backwater from Trinity River.


[Elevation, in feet; discharge, in cubic feet per second; and accumulated runoff, in inches, at indicated time,April 28,1966]

Hour

011501300145020002150230024503000315033003450400

Elevation

420.3424.8425.3425.4425.8426.0426.4426.0425.8425.5424.6

Discharge

01,3404,3004,9005,0005,6005,8006,3505,8005,6005,1504,000

Accumu lated runoff

0.07.29.54.80

1.091.391.722.012.302.572.77

Hour

04150430044505000515053006000900120015002400

Elevation

423.2422.4421.6421.0420.4419.8419.0415.6414.1413.5412.8

Discharge

2,8002,2501,8501,5801,3701,2001,000

430107331.8

Accumu lated runoff

2.923.033.133.213.283.373.734.004.064.114.11

BACHMAN BRANCH AT WALNUT HILL LANE, DALLAS, TEX.

(Miscellaneous site)

Location. Lat 32°52'48" N., long 96°49'26" W., at bridge on Walnut Hill Lane, Dallas, Dallas County, 5.4 miles upstream from Interstate 35E.

Drainage area. 4.73 sq mi.Elevation record. From floodmarks. Datum is mean sea level, datum of 1929,

supplementary adjustment of 1953.Discharge record. Maximum discharge by contracted-opening measurement.Maximums. April 28,1966 : Discharge, 10,400 cfs (elev, 511.0 ft).

1962 to April 28, 1966: Discharge, 6,160 cfs on Oct. 8, 1962 (elev, 512.8 ft, from floodmarks).

Remarks. Dam about 1,000 ft downstream from Walnut Hill Lane removed since Oct. 8, 1962 flood.

SLAUGHTER BRANCH AT WALNUT HILL LANE, DALLAS, TEX. (Miscellaneous site)

Location. Lat 32°52'48" N., long 96°49'03" W., at Culvert on Walnut Hill Lane, Dallas, Dallas County, 1.1 miles upstream from mouth.


supplementary adjustment of 1953.Discharge record. Maximum discharge by computation of flow through culvert

and flow over road.Maximum. April 28,1966: Discharge, 4,770 cfs (elev, 530.8 ft).

BACHMAN BRANCH AT NORTHWEST HIGHWAY, DALLAS, TEX. (Miscellaneous site)

Location. Lat 32°51'48" N., Long 96°49'48" W., at culvert on Northwest High way (Loop 12), Dallas, Dallas County.


supplementary adjustment of 1953.Dioharge record. Maximum discharge by computation of flow through culvert

and over road.Maximums. April 28,1966 : Discharge, 14,400 cfs (elev, 484.2 ft).

1962 to April 28, 1966: Discharge, 8,530 cfs on Oct. 8, 1962 (elev, 479.9 ft).


8-557. BACHMAN BRANCH AT MIDWAY ROAD, DALLAS, TEX.

Location. Lat 32°51'26" N., long 96°50'12" W., on right bank at downstream side of bridge on Midway Road at Dallas, Dallas County, 1,400 ft south of Northwest Highway, 1.5 miles upstream from Bachman Lake Dam, and 6.0 miles northwest of Dallas City Hall.

Drainage area. 10.0 sq mi.Elevation record. Water-stage recorder graph to 0330 hours. Graph drawn on

basis of floodmarks and wire-weight gage readings. Datum of gage is mean sea level, datum of 1929, supplementary adjustment of 1953.

Discharge record. Stage-discharge relation defined by current-meter measure ments below 4,000 cfs; by contracted-opening measurements of 5,300, 9,200, and 16,000 cfs.

Maximums April 28, 1966: Discharge, 16,000 cfs 0410 hours (elev, 467.97 ft, from floodmarks).

1963 to April 28, 1966: Discharge, 5,170 cfs May 10, 1965 (elev, 461.43 ft). Since at least 1900: Discharge, 9,200 cfs Oct. 8, 1962 (elev, 465.6 ft, from

floodmarks).


Hour

0000020003000330040004100420050006000700

Elevation

449.72449.71455.8461.7467.2467. 97467.1463.2457.4454.9

Discharge

2020

1,7005,410

13,10016,00012,8006,6802,4901,320

Accumu lated runoff

0.01.21.63

1.301.722.543.403.794.00

Hour

0800090010001100120013001400160020002400

Elevation

453.9453.0452.4452.0451.6451.2450.8450.5450.2450.0

Discharge

955680525425340260180122

7044

Accumu lated runoff

4.144.254.334.404.454.494.534.594.634.65

BACHMAN BRANCH AT WEBBS CHAPEL ROAD, DALLAS, TEX.(Miscellaneous site)

Location. Lat 32°51'33" N., long 96°51'21" W., at bridge on Webbs ChapelRoad, Dallas, Dallas County.


supplementary adjustment of 1953. Discharge record. Maximum discharge by contracted-opening measurement and

computation of flow over road. Maximum. April 28, 1966: Discharge, 18,200 cfs (elev, 445.68 ft).

BACHMAN BRANCH AT BACHMAN LAKE, DALLAS, TEX.

(Miscellaneous site)

Location. Lat 32°50'55" N., long 96°52'16" W., at spillway of Bachman Lake,Dallas, Dallas County.


supplementary adjustment of 1953. Discharge record. Maximum discharge by computation of flow over spillway

and flow over embankment. Maximum. April 28,1966: Discharge, 15,000 cfs (elev, 444.6 ft).


TURTLE CREEK BELOW McFARLIN BOULEVARD, DALLAS, TEX.(Miscellaneous site)

Location. Lat 32°50'35" N., long 96°47'54" W., at dam 600 ft downstream fromMcFarlin Boulevard, Dallas, Dallas County.


supplementary adjustment of 1953. Discharge record. Maximum discharge determined by computation of flow over

dam. Maximum. April 28,1966: Discharge, 5,080 cfs (elev, 530.9 ft).

8-565. TURTLE CREEK AT DALLAS, TEX.

Location. Lat 32°48'26" N., long 96°48'08" W., on left bank 68 ft upstream from Hall Street at Dallas, Dallas County, and 2.0 miles north of Dallas County Courthouse.

Drainage area. 7.98 sq mi.Elevation record. Water-stage recorder graph. Datum of gage is mean sea level,

datum of 1929, supplementary adjustment of 1947.Discharge record. Stage-discharge relation defined by current-meter measure

ments below 2,500 cfs and by computation of flow over dam and flow over embankment at 12,200 cfs.

Maximums. April 28, 1966: Discharge, 12,200 cfs 0410 hours (elev, 438.67 ft). 1951 to April 28, 1966: Discharge, 4,650 cfs Oct. 1, 1959 (elev, 436.23 ft). Since at least 1903: Discharge, that of April 28,1966.


Hour

00000215023002450300031503300345040004100415043004450500051505300545

Elevation

429.92429.93430.18430. 47430.64433.38435. 77437. 17438.40438.67438.53437.83436.37435.43434.33432. 97432.33

Discharge

9.2103897

1521,8804,1306,160

10,40012,20011,2007,9004,8503,7502,6901,5501,040

Accumu lated runoff

0.0.0.01.01.02.11.31.61

1.031.321.692.072.312.492.622.692.74

Hour

06000615063006450700071507300800083009001000110012001300150018002400

Elevation

432.28432. 21431.87431.64431. 46431. 32431.20430.98430.82430.70430.59430.50430.44430.39430.30430.24430.20

Discharge

1,0109627446065204403862892241761341068977594841

Accumu lated runoff

2.792.842.882.902.932.952.983.013.033.063.083.103.123.143.173.213.23

8-571. WHITE ROCK CREEK AT KELLER SPRINGS ROAD, DALLAS, TEX.

Location. Lat 32°58'13" N., long 96°48'19" W., on left bank at downstreamside of bridge on Keller Springs Road in Dallas, 0.5 mile upstream from St.Louis Southwestern Railway Lines bridge, 0.9 mile upstream from SpankyBranch, and 13 miles north of Dallas County Courthouse.

Drainage area. 29.4 sq mi. Elevation record. Water-stage recorder graph. Datum of gage is mean sea level,

datum of 1929, supplementary adjustment of 1953.


Discharge record. Stage-discharge relation defined by current-meter measure ments below 5,000 cfs and by contracted-opening measurements at 37,900 cfs.

Maximums. April 28, 1966: Discharge, 9,020 cfs 0430 hours (elev, 565.60 ft).1961 to April 28, 1966: Discharge, 37,900 cfs Sept. 25 1964 (elev, 574.51 ft).Since at least 1886: Discharge, that of Sept. 21, 1964.

[Elevation, in feet; discharge, in cubic feet per second; and accumulated runofE, in inches, at indicated time,April 28,1966]

Hour

000001000130020003000330040004300500060007000730080009001000

Elevation

546.79546.78546.8549.5560.4564.4565.4565.60565.3562.1552.7552.0554.2557.4558.15

Discharge

201921

5584,4007,5808,7809,0208,6605,5801,4101,2001,8603,1403,480

Accumu lated runofE

000.02.20.40.63.87

1.211.501.561.591.661.832.01

Hour

11001200130014001500160017001800190020002100220023002400

Elevation

553.7550.5549.45550.7554.0555.2552.1550.1549.3548.85548.68548.50548.36548.33

Discharge

1,710789546846

1,8002,2601,230

702510402361318286279

Accumu lated runofE

2.102.142.172.222.312.432.502.532.562.582.602.622.632.64

8-571.2 SPANKY BRANCH AT McCALLTTM LANE, DALLAS, TEX.(Crest-stage partial-record station)

Location. Lat 32°57'58" N., long 96°48'11" W., at bridge on McCallum Lane, Dallas, Dallas County, 0.5 mile above mouth.

Drainage area. 6.77 sq mi.Elevation record. Crest stages only. Datum of gage is mean sea level, datum of

1929, supplementary adjustment of 1953.Discharge record. Stage-discharge relation defined by current-meter measure

ments below 370 cfs; and by slope-area measurements at 4,020 cfs, and computation of flow through culvert and flow over road at 7,870 cfs.

Maximums. April 28,1966: Discharge, 5,000 cfs (elev, 569.3 ft).1962 to April 28,1966: Discharge, 7,870 cfs Sept. 21,1964 (elev, 572.02 ft). Since at least 1917: Discharge, that of Sept. 21,1964.

ARMSTRONG BRANCH AT MELROSE DRIVE, RICHARDSON, TEX. (Miscellaneous site)

Location. Lat 32°58'16" N., long 96°45'19" W., at culvert on Melrose Drive, Richardson, 1.6 miles upstream from mouth, and 2.2 miles northwest of Rich ardson City Hall, Dallas County.


supplementary adjustment of 1953.Discharge record. Maximum discharge determined by flow through culvert

measurement.Maximum. April 28,1966: Discharge, 1,290 cfs (elev, 631.50 ft).

B34 FLOODS OF 1'966 IN THE UNITED STATES

8-571.4 COTTONWOOD CREEK AT FOREST LANE, DALLAS, TEX.(Crest-stage partial-record station)

Location. Lat 32°54'33" N., long 96°45'54" W., at bridge on Forest Lane,Dallas, Dallas County, 0.2 mile above Floyd Branch.

Drainage area. 8.50 sq mi. Elevation record. Crest stages only. Datum of gage is mean sea level, datum of

1929, supplementary adjustment of 1953.Discharge record. Maximum discharge by slope-area measurement at 17,600 cfs. Maximums. April 28,1966: Discharge, 17,600 cfs (elev, 512.32 ft).

1962 to April 28,1966: Discharge, 17,400 cfs Oct. 8,1962 (elev, 511.74 ft). Since at least 1892: Discharge, that of April 28, 1966.

FLOYD BRANCH AT VALLEY VIEW ROAD, DALLAS, TEX.(Miscellaneous site)

Location. Lat 32°55'22" N., long 96°44'51" W., at culvert on Valley View Road,Dallas, Dallas County, 1.4 miles upstream from partial-record station, 8-571.6Floyd Branch at Forest Lane, Dallas, Tex.


supplementary adjustment of 1953. Discharge record-. Maximum discharge determined by measurement of flow

through culvert and flow over road. Maaimums. April 28,1966: Discharge, 6,170 cfs (elev, 547.0 ft).

1962 to April 28, 1966: Discharge, 4,030 cfs Oct. 8, 1962 (elev, 540.18 ft).

8-S71.6 FLOYD BRANCH AT FOREST LANE, DALLAS, TEX.(Crest-stage partial-record station)

Location. Lat 32°54'33" N., long 96°45'34" W., at bridge on Forest Lane, Dallas,Dallas County, 0.3 mile above mouth.

Drainage area. 4.17 sq mi. Elevation record. Crest stages only. Datum of gage is mean sea level, datum of

1929, supplementary adjustment of 1953. Discharge record. Maximum discharge by contracted-opening measurement and

computation of flow over road. Maximums. April 28,1966: Discharge, 8,590 cfs (elev, 514.19 ft).

1961 to April 28, 1966: Discharge, 4,850 cfs Oct. 8, 1962 (elev, 512,63 ft). Since at least 1909: Discharge, that of April 28,1966.

8-572. WHITE ROCK CREEK AT GREENVILLE AVENUE, DALLAS, TEX.

Location. Lat 32°53'21" N., long 96°45'23" W., on left bank 20 ft downstream from bridge on Greenville Avenue in Dallas, 1.1 miles downstream from Texas and New Orleans Railroad Co. bridge, 1.2 miles downstream from Cottonwood Creek, 2.9 miles upstream from White Rock Lake, and 8.2 miles northeast of Dallas County Courthouse.

Drainage area. 66.4 sq mi.Elevation record. Water-stage recorder graph. Datum of gage is mean sea level,

datum of 1929, supplementary adjustment of 1953.Discharge record. Stage-discharge relation defined by current-meter

measurements.


Maximums. April 28, 1966: Discharge, 27,000 cfs 0330 hours (elev, 489.47 ft). 1961 to April 28, 1966: Discharge, 38,100 cfs Sept. 21, 1964 (elev, 490.43 ft). Since at least 1886: Discharge, that of Sept. 21,1964.

[Elevation, in feet; discharge, in cubic feet per second; and accumulated runoff, in inches, at indicated time,April 28, 1966]

Hour

00000130020003000330040005000530060007000800090010001100

Elevation

472.08472.02475.5487.6489.47489.0488.5488.35488.2488.0487.8487.5487.2487.0

Discharge

10496

6308,390

27,00022, 10016,90015,40013,80011,8009,7608,1307,5207,120

Accumu lated runoff

00.02.16.48.86

1.161.341.581.862.082.272.452.57

Hour

11301200130014001500160017001800190020002100220023002400

Elevation

486.9486.2482.6479.5481.5484.5485. 16483.6481.0478.4477.4477.0476.0476.2

Discharge

6,9405,8702,3701,3001,8803,5304,3702,9401,7001,110

938870710742

Accumu lated runoff

2.652.762.812.842.892.973.073.143.183.213.233.253.263.27

8-573. WHITE ROCK CREEK AT WHITE ROCK LAKE, DALLAS, TEX.

Location. L&t 32°48'31" N., long 96°43'32" W., on right bank 500 ft upstream from right end of White Rock Lake spillway, 1,500 ft upstream from bridge on Garland Road (State Highway 78) at Dallas, Dallas County, and 10.3 miles upstream from mouth.

Drainage area. 100 sq mi.Elevation record. Water-stage recorder graph. Datum of gage is mean sea level,

datum of 1929, supplementary adjustment of 1961.Discharge record. Stage-discharge relation denned by current-meter measure

ments.Maximums. April 28, 1966: Discharge, 18,800 cfs 0800 hours (elev, 463.82 ft, on

recorder chart; 463.87 ft, from crest-stage gage).1962 to April 28, 1966: Discharge, 28,300 cfs Sept. 21, 1964 (elev, 465.60 ft). Since 1910: Discharge, that of Sept. 21,1964.


Hour

000002000300040005000600070008000900

Elevation

458.43458.44458.85459. 80461. 70463.10463. 67463.82463.75

Discharge

193204900

3,1209,400

15,40018,00018,80018,400

Accumu lated runoff

0.01.02.07.22.45.73

1.021.31

Hour

10001100120014001600180021002400

Elevation

463.50463.15462. 75462. 01461.34460.79460.31459. 93

Discharge

17,20015,60013,80010,6008,0406,1204,6303,490

Accumu lated runoff

1.581.822.142.472.722.963.173.25

8-573.2 ASH CREEK AT HIGHLAND DRIVE, DALLAS, TEX.

(Crest-stage partial-record station)

Location. Lat 32°48'18" N., long 96°43'04" W., at bridge on Highland Road,Dallas, Dallas County, 0.4 mile upstream from mouth.

Drainage area. 6.92 sq mi.

B36 FLOODS OF T966 IN THE UNITED STATES

Elevation record. Crest stages only. Datum of gage is mean sea level, datum of1929, supplementary adjustment of 1961.

Discharge record. Maximum discharge by contracted-opening measurement. Maximum*. April 28,1966: Discharge, 5,180 cfs (elev, 431.54 ft).

1963 to April 28, 1966: Elevation, 430.99 ft April 28, 1963 (discharge not determined).

8-573.4 FORNEY CREEK AT LAWNVIEW AVENTTE, DALLAS, TEX.

(Crest-stage partial-record station)

Location. Lat 32°46'45" N., long 96°43'02" W., at culvert on Lawnview Avenue,Dallas, Dallas County, and 0.8 mile above mouth.

Drainage area. 1.84 sq mi. Elevation record. Crest stage only. Datum of gage is mean sea level, datum of

1929, supplementary adjustment of 1961. Discharge record. Maximum discharge by a contracted-opening measurement

and computation of flow over road. Maximums April28,1966: Discharge, 1,090cfs (elev, 435.42 ft).

1963 to April 28, 1966: Elevation, 431.36 ft April 28, 1963 (discharge not determined).

8-574. WHITE ROCK CREEK AT SCYENE ROAD, DALLAS, TEX.

Location. Lat 32°45'57' N., long 96°43'50" W., on left bank 30 ft downstream from Texas and New Orleans Railroad Co. bridge, 125 ft downstream from Scyene Road (State Highway 352) at Dallas, Dallas County, 4.5 miles east of Dallas County Courthouse, and 5.8 miles above mouth.

Drainage area. 125 sq mi. Elevation record. Water-stage recorder graph. Datum of gage is mean sea

level, datum of 1929, supplementary adjustment of 1961.Discharge record. Stage-discharge relation defined by current-meter measure

ment below 15,000 cfs and by contracted-opening measurement of 30,200 cfs. Maximums. April 28, 1966: Discharge, 21,500 cfs 1000 hours (elev, 402.99 ft).

1962 to April 28, 1966: Discharge, 30,200 cfs Sept. 21, 1964 (elev. 404.30 ft). Since at least 1886: Discharge, that of Sept. 21, 1964; elevation, 409.2 ft

May 26, 1908 (backwater from Trinity River).


Hour

000001000230030003300400050006000630070008000836

Elevation

395. 81395. 77395.80396. 30402.70402.40402.80402.45402.42402.68402.90402.95

Discharge

228221226320

19,30015,90020,00016,60016,30018,00020,80021,200

Accumu lated runoff

00.01.01.13.28.52.68.78.95

1.141.27

Hour

09001000110012001300140015001700200022002400

Elevation

402.97402.99402.96402.90402.75402.63402.55402.32401.45400.94400.75

Discharge

21,40021,50021,30020,80019,60018,60017,80012,5007,5505,2504,790

Accumu lated runoff

1.471.742.002.262.502.733.063.453.683.813.87

APRIL 28, 1966., NORTHERN PART OF DALLAS, TEXAS B37

SELECTED REFERENCES

Gilbert, C. R., 1963, Floods on White Rock Creek above White Rock Lake at Dallas, Texas: U.S. Geol. Survey open-file report, 21 p.

Gumbel, E. J., 1941, The return period of flood flows, in The annals of mathemati cal statistics: Hay ward, Calif., California State Col. Inst. Math. Statistics, v. 12, p. 163-190.

Ruggles, F. H, Jr., 1964a, Frequency and extent of flooding on lower White Rock Creek at Dallas, Texas: U.S. Geol. Survey open-file report.

1964b, Floods on Bachman Branch and Joes Creek at Dallas, Texas: U.S. Geol. Survey open-file report.

1966, Flood of October 8, 1962, on Bachman Branch and Joes Creek atDallas, Texas: U.S. Geol. Survey Hydrol. Inv. Atlas HA-240.

Ruggles, F. H., Jr., and Gilbert, C. R., 1967, Floods on White Rock Creek atDallas, Texas, in 1962 and 1964: U.S. Geol. Survey Hydrol. Inv. AtlasHA-238.

U.S. Weather Bureau, 1955, Rainfall intensity-duration-frequency curves: U.S.Weather Bur. Tech. Paper 25.

1961, Rainfall frequency atlas of the United States: U.S. Weather Bur.Tech. Paper 40.

U.S. GOVERNMENT PRINTING OFFICE : 1969 O 335-3S9

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