Flash Flood Alley Segements

South Central Texas June 30-July 7, 2002

Storm Summary
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Fatalities,
Survivors
& Rescue Efforts
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Property Damage
& Relief Efforts
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Success Stories
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Regional Flood
Histories
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Local
Programs
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Resources
& Publications
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Known Hazards
in Central Texas

 

Rough Sea Shore
South Central Texas
June 30-July 7, 2002
Storm
(Compared to: ->)
South Central Texas October, 1998
35 inches
Max. Precipitation:
30 inches
12
Deaths:
32
One Billion (approx.)
Damage
1.5 Billion (approx.)
July 2002

Could Have Been Worse:
The majority of the water fell in the upper river basins of rivers like the Guadalupe and Medina (as opposed to the lower basin deluge of '98). This brought Canyon Dam into its most important role since it was built. At the flood peak, the dam held back 70, 000 cfs - though 70,000 more flooded over the spillway.

Could Have Been Worse


Full Size

Instant Canyon:
Readers are urged to see the images of the amazing canyon cut by the spillway flow. This image comes from larger collection taken by County Engineer Tom Hornseth which can be viewed on the Comal County Engineer's Office.

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Instant Canyon

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San Antonio River Tunnels Prove Valuable Again:
The San Antonio River Tunnels once again proved their value to that city as they diverted water safely underneath downtown. This tunnel was built by the San Antonio River Authority which also manages a series of structural controls that played an important role in the July Storm.

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San Antonio River Tunnels

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Structural Controls:
In retrospect, this storm highlighted the value of (and reliance on) structural controls somewhat akin to the December, 1991 storms showcasing the LCRA's management of its series of dams along the Highland Lakes.

 

Structural Controls

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Floodplain Remapping:
Perhaps the most interesting story to watch coming out this storm is the process of remapping the flood plain maps along the heavily populated lower Guadalupe River. For example, the 1986 map showing streamflow designation for a 100-year flood on the Guadalupe River is radically changing from 26,000 cfs to 88,000 cfs. This is a story to watch closely with interesting changes also taking place in the insurance landscape.

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Flood Plan Remapping

Full Size

Death Toll:

Lastly, the number of deaths from this storm was 12, thankfully much lower than the 98 storm which killed 32.. Much is this has to do with the gradual build of the storm and the subsequent warnings that were issued. Another factors in the reduction of deaths may also be attributed to the fact that Texas has had a number of deadly storms recently so public attention may be somewhat raised.

As a side-note: 56-year old San Antonio man has refused to pay a $400 fee after he drove around a barricade and had to be rescued from floodwaters. The man, who could not swim, was rescued with a mere six-inch air space remaining inside his car. The man suffered from hypothermia and spent the night at a local hospital.

A 1992 ordinance enables the City of San Antonio to issue a $400 fine to anyone who has to be rescued at low water crossings that are clearly marked.

 


Death Toll

 

Storm Description (from USGS)

On June 30, 2002, a low-pressure system migrating westward from Florida combined with a flow of deep tropical moisture from the Gulf of Mexico and moved over southern Texas. The system hit a wall of high pressure and stalled over the central and south-central parts of the State. For 8 days, the storm system continued to draw moisture from the Gulf, which triggered several massive storms throughout much of the area. As much as 35 inches of rainfall fell during the event, with heaviest depths occurring in the Texas Hill Country northwest of San Antonio. Flooding affected about 80 counties in Texas.

Heavy rain also fell in parts of west Texas, including Abilene, where 12-14 inches of rain in the pre-dawn hours of July 6 caused flooding that required numerous evacuations. Heavy rains also caused Lake Brownwood to overflow, causing evacuations and flooding in parts of Brownwood.

The floods caused twelve deaths and damage to about 48,000 homes. Nearly 250 flood rescue calls were reported, more than 130 roads were closed, and thousands of homes and businesses lost electrical power and telephone service. Twenty-four counties have been identified by the Federal Emergency Management Agency (FEMA) as Federal Declared Disaster areas--14 counties are eligible for individual assistance and 10 counties for individual and public assistance. Emergency management representatives have not yet assessed the total cost of damages.

The storms produced large volumes of runoff and as many as four flood peaks at each of many streamflow-gaging stations in the Brazos, Colorado, and Guadalupe River Basins. Record flood stages occurred at sites on the Medina River, San Antonio River, Sabinal River, and Nueces River. For the first time since it filled in 1968, Canyon Lake (northeast of San Antonio) poured over its spillway, adding to the flooding in the Guadalupe River. Emergency managers also were concerned about the 90-year-old dam at Medina Lake (west of San Antonio). Medina Lake topped its spillway and rose to within 18 inches of the top of the dam. Areas downstream from the dam were evacuated as a precaution to the fear of dam failure.