1

RAIN BY THE

CUBIT The Great Southeast Texas Flood of 1994

Andy Yung, P.E., CFM

Dodson | A Walter P.

Moore Company

Duane Barrett, P.E.,

CFM HDR

Engineering, Inc.

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Llanite is found only in the vicinity of Llano, Texas. Although Llanite is an igneous rock, co-author Duane Barrett will always associate it with water!

LLanite 2

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General Timeline

October 15, 1994 (Saturday)

Pacific Hurricane Rosa Meets a Gulf Coast Warm Front Over Texas

Rainfall Begins

October 16, 1994 (Sunday)

Rainfall Abates in the Early Morning

Begins to Rebuild and Intensify in the Evening

October 17, 1994 (Monday)

Large Cell Develops Southwest of Waller, Texas - Early Morning

Flooding Overtops U.S. Highway 290 near Waller

HCFCD Mobilizes Flood ALERT Activities

October 18, 1994 (Tuesday)

Jet Stream Southward & Heavy Rainfall Comes to Harris County

Most Bayous and Creeks in Harris County Report Major Flooding

October 19, 1994 (Wednesday)

Aerial Reconnaissance Conducted Across Harris County

The Sun Appears!

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2

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Geography

The 1994 flood affected a huge geographic area covering 38 counties in southeast Texas. The map at right illustrates the extent of the affected area, which is roughly the size of the state of Maine.

Lake

Conroe

Lake

Houston

Lake

Livingston

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027469

Meteorology

Remnants of Pacific Hurricane Rosa interacted with a warm front from the Gulf of Mexico, creating a boundary along within which rainfall events were entrained.

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A Real “Texas Flood”

The song “Texas Flood” by Stevie Ray Vaughan provides an appropriate musical backdrop for this amazing video created from radar images of the 1994 event.

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October 15-19, 1994

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Rainfall Totals

Rainfall totals of over 20 inches were recorded at 4 gages within Harris County. More than 15 inches was recorded at 18 gages. Finally, more than 10 inches was recorded at 34 gages!

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027472

Berry Bayou at Forest Oaks Drive

Rainfall Data - HCOEM Gage 320

0

5

10

15

20

25

10

/14

/94 1

2:0

0 A

M

10

/14

/199

4 1

2:0

0 P

M

10

/15

/199

4 1

2:0

0 A

M

10

/15

/199

4 1

2:0

0 P

M

10

/16

/199

4 1

2:0

0 A

M

10

/16

/199

4 1

2:0

0 P

M

10

/17

/199

4 1

2:0

0 A

M

10

/17

/199

4 1

2:0

0 P

M

10

/18

/199

4 1

2:0

0 A

M

10

/18

/199

4 1

2:0

0 P

M

10

/19

/199

4 1

2:0

0 A

M

10

/19

/199

4 1

2:0

0 P

M

10

/20

/199

4 1

2:0

0 A

M

Cu

mu

lati

ve R

ain

fall (

inch

es)

Rainfall Data for HCFCD Gage 320

24 Hours

13 Inches of

Rainfall in

24 Hours

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Greens Bayou at Mount Houston Road

Rainfall Data - HCOEM Gage 1600

0

5

10

15

20

25

10

/14

/199

4 1

2:0

0 A

M

10

/14

/199

4 1

2:0

0 P

M

10

/15

/199

4 1

2:0

0 A

M

10

/15

/199

4 1

2:0

0 P

M

10

/16

/199

4 1

2:0

0 A

M

10

/16

/199

4 1

2:0

0 P

M

10

/17

/199

4 1

2:0

0 A

M

10

/17

/199

4 1

2:0

0 P

M

10

/18

/199

4 1

2:0

0 A

M

10

/18

/199

4 1

2:0

0 P

M

10

/19

/199

4 1

2:0

0 A

M

10

/19

/199

4 1

2:0

0 P

M

10

/20

/199

4 1

2:0

0 A

M

Cu

mu

lati

ve R

ain

fall (

inch

es)

Rainfall Data for HCFCD Gage 1600

13 Inches of

Rainfall in

24 Hours

24 Hours

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Cedar Bayou at U.S. Highway 90

Rainfall Data - HCOEM Gage 1740

0

5

10

15

20

25

30

35

10

/14

/199

4 1

2:0

0 A

M

10

/14

/199

4 1

2:0

0 P

M

10

/15

/199

4 1

2:0

0 A

M

10

/15

/199

4 1

2:0

0 P

M

10

/16

/199

4 1

2:0

0 A

M

10

/16

/199

4 1

2:0

0 P

M

10

/17

/199

4 1

2:0

0 A

M

10

/17

/199

4 1

2:0

0 P

M

10

/18

/199

4 1

2:0

0 A

M

10

/18

/199

4 1

2:0

0 P

M

10

/19

/199

4 1

2:0

0 A

M

10

/19

/199

4 1

2:0

0 P

M

10

/20

/199

4 1

2:0

0 A

M

Cu

mu

lati

ve R

ain

fall (

inch

es)

Rainfall Data for HCFCD Gage 1740

21 Inches of

Rainfall in

Less Than 24

24 Hours

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Watershed-Wide Rainfall

The storm event of October 1994 produced staggering rainfall amounts, especially considering the size of the area affected.

Source: Steve Johnson, P.E.

The average rainfall depth over the 2,880-square mile San Jacinto River watershed was 19.5 inches.

The 1% annual chance rainfall 4-day rainfall is 14.9 inches.

A total of 1.9 million acre-feet of runoff passed through Lake Houston.

The average runoff over the watershed was 12.7 inches.

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Area-Wide Rainfall 12

Rainfall was heavy over the entire 38-county area affected by the storm, as evidenced by the figure at right. The area affected measures roughly 300 miles x 170 miles.

18”

12”

21”

13” 23”

9”

29”

17”

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Reservoirs React

In response to the heavy rainfall over their respective watersheds, water levels in Lakes Conroe, Houston, and Livingston rose rapidly, and spillways went into operation.

Atascocita Area on

Lake Houston (Photo:

HCFCD)

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The Lake Livingston discharge reached a maximum of 110,600 cfs .

The maximum lake level was 134.38 ft, 3.38 feet above the normal

pool elevation of 131.00 ft. All this despite that the storm affected

only the lower portion of the watershed! (Images: USGS, TRA)

Lake Livingston Watershed Area = 16,600

square miles at Lake

Livingston

The Trinity River Watershed

Lake

Livingston

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Lake Conroe reached a maximum level of 205.88 feet (4.88 feet above the normal conservation pool of 201.00 ft). A peak discharge of 56,000 cfs was recorded a short distance downstream of the dam. (Photo: SJRA)

Lake Conroe Watershed Area = 448 square miles

Lake Conroe Division Systems Manager Ike Barrett arrived at

the Lake Conroe dam early on the morning of October 17 to find

the lake level approximately two feet above the tops of the

tainter gates. Barrett immediately ordered the gates to be

opened to prevent damage.

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The Lake Houston discharge reached a maximum value of

359,000 cfs with a corresponding lake elevation of 52.8 feet, 8.3

feet above the crest elevation of the 3,160-foot long overflow

spillway. (Photo: HCFCD)

Lake Houston

Watershed Area =

2,830 square miles

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Lake Houston Gated Section of Spillway (Photo: HCFCD)

Lake Houston 17

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Rivers and Creeks Rise 18 -

i:iiUSGS

l l 1.0000 ... " ~ .. ...

"B 1000

100

i:iiUSGS

USGS 08068000 W Fk San Jacinto Rv nr Conroe, TX

Oct 13 1994

Oct :1.5 1994

Oct 17 1994

--e-- Dail.y n ean discharge

Oct :1.9 1994

Oct 21. 1994

Oct 23 1994

- Period of approved data

USGS 08068500 Spring Ck nr Spring, TX

Oct 2! 1994

l 60000 r-----------------------------~==~r------------------------.

c.. 8. 10000

... ~ " .... .g " " .. ~ ~

1.000

c: :100 ,_

~ Oct 13

1.994 Oct 1:5

1994 Oct 17

1994 Oct 19

1994 Oct 21

1994 Oct 23

1.994

--e-- Dail~_:~ nean d ischarge - Period of approved data - Estinated dail.y t'lean discharge

Oct 2! 1.994

i:iiUSGS USGS 08070000 E Fk San Jacinto Rv nr Cleveland, TX

~RRBB .---------------,-------------, -g 30000

i 2 0000

t 10000

1 000

100

Oct 13 1994

Oct :1.5 1994

Oct 17 1994

--e-- Dail.y t'lean discharge

Oct 19 1994

Oct 21. 1994

Oct 23 1994

- Period of approved data

i:iiUSGS

1 20000

~ 10000

t t ~ 1000 .. . .. "B ~

] ~

~

100

USGS 08070500 Caney Ck nr Splendora, TX

Oct 1.3 1994

Oct 1.5 1994

Oct 17 1994

Oct :19 1.994

Oct 21 1994

Oct 23 1994

--e-- Dai ly nean disc harge - Period of approved da ta - Es tina ted dai.ly ~tean dis c h a rge

Oct 2! 1994

Oct 2! 1994

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Cypress Creek overflowed its banks, sending thousands of acre-feet of

storm water cross-country to the Addicks and Barker Reservoir

watersheds and inundating thousands of acres of land. (Photo: HCFCD)

Cypress Creek Overflows

Cypress Creek

Channel

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Inverness Forest Levee on Cypress Creek at the Hardy Toll Road

(Photo: HCFCD)

Cypress Creek 20

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Maximum flood levels along Spring Creek exceeded FEMA 1%

annual chance values by 4.0 to 4.5 feet. The Northgate Crossing

levee was overtopped on October 18, 1994. This is one of only two

levee systems in Harris County. (Photo: HCFCD)

Northgate Crossing Levee 21

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Northgate Crossing Levee and Pump House (Photo: HCFCD)

Northgate Crossing Levee 22

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West Fork San Jacinto River at U.S. 59 (Photo: HCFCD)

West Fork of the San Jacinto River 23

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San Jacinto River at I-10 (Photo: HCFCD)

Lower San Jacinto River 24

IH-10

Barges

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Record Stream Flows

Stream flows

in excess of

1% annual

chance

values were

recorded at

19 USGS

gages within

the affected

area! New

historical

maxima were

recorded at

25 of 43

stations!

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Peak Discharge Comparisons

The 1994 flood produced peak flows on the San Jacinto and Lavaca Rivers that exceeded historical maxima from much larger watersheds.

Location Drainage

Area

(sq mi)

Peak

Discharge

(cfs)

Peak

Discharge

(cfs/sq mi)

San Jacinto

River D/S Lake

Houston

2,880 360,000 125

Lavaca River at

Edna, TX

817 150,000 184

Spring Creek at

Riley-Fuzzel Rd.

420 78,800 188

Trinity River at

Liberty, TX

17,500 135,000 7.7

Brazos River at

Richmond, TX

45,100 300,000 6.7

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Banana Bend/Rio Villa Area Below Lake Houston (Photo: HCFCD)

Photos 27

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Apartments in Forest Cove Area (Photo: HCFCD)

Photos 28

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Little Cypress Creek at Cypress-Rose Hill Road (Photo: HCFCD)

Photos 29

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Toys-R-Us on U.S. 59 at West Fork San Jacinto River (Photo:

HCFCD)

Photos 30

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U.S. 59 North Bound Feeder Road at West Fork San Jacinto River

(Photo: HCFCD)

Photos 31

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Power Line Near the Upper End of Lake Houston on the West Fork of

the San Jacinto River (Photo: HCFCD)

Photos 32

Base of Power

Transmission

Tower

Displaced

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Cypress Creek at Aldine-Westfield (Photo: HCFCD)

Photos 33

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West Fork San Jacinto River Near Lake Houston (Photo: HCFCD)

Photos 34

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Forest Cove Area near the West Fork San Jacinto River (Photo:

HCFCD)

Photos 35

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Cypress Creek at Huffmeister Road (Photo: HCFCD)

Photos 36

“Allsafe

Insurance”

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Pea Gravel is found everywhere. Although this small stone is used

primarily in gardening, co-author Andy Yung will always associate it

with the massive flood of 1994!

Pea Gravel 37

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Breakage of pipelines across the river led to a fire that sent plumes of

black smoke hundreds of feet into the air. (Photo: Houston Chronicle)

The San Jacinto River Fire (October 20th) 38

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San Jacinto River Shortcut across Banana Bend/Rio Villa Meander. This is near the location of exposed pipelines; note burned trees. (Photo: HCFCD)

Photos 39

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Conclusions 40

Extreme rainfall events will continue to occur.

Are they “acts of God” that may be ignored, or should

they be considered when establishing flood protection

requirements?

The adoption of criteria that exceed FEMA minimum

requirements should be considered by communities to

guard against severe events.

Design of critical facilities should consider such extreme

events.

We must study and learn from these events.

Improvements in predictive technology and warning

systems must continue in order to reduce the loss of life

that occurs during such extreme weather events.

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References

U.S. Geological Survey

(USGS)

National Oceanic &

Atmospheric

Administration (NOAA)

Harris County Flood

Control District (HCFCD)

San Jacinto River Authority

(SJRA)

Trinity River Authority

(TRA)

Harris County Office of

Emergency Management

(HCOEM)

The Houston Chronicle

Steve Johnson, P.E., CFM

Public Agencies Private Sources

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