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Dr. Bob Visits Canyon Lake Gorge

What does catastrophic flooding today tell us about the truth of the global flood?

Application: Catastrophic events, like the global flood, are responsible for most of the major geological features we observe today.

In this L.I.F.E. Lesson, Dr. Bob visits Canyon Lake Gorge in the Texas Hill Country. This was the site of a major flood event in 2002 that provides insight into the evidence for the global flood how the retreating flood waters carved the canyons visible in the world today..

Supplemental Information

The 2002 flood was the first time that floodwaters flowed over the Emergency Spillway since this reservoir was completed in 1964. It was expected that it would take five years to fill it, but by 1967 the rains in this area of Central Texas had already filled it. This was a prelude to how massive this watershed's impact would be.

The Guadalupe River basin forms a part of "Flash Flood Alley" which is one of the river basins most prone to flash flooding in the world. Nine people were killed by the flood over a 20 miles stretch of the river, which damaged or destroyed 48,000 homes and cost around $1 billion in damages.

Constructed to provide flood control and water conservation, the Canyon Dam and Reservoir Project was designed to reduce the damage from flooding events that often hit the Lower Guadalupe River Basin. Once such event occurred in the summer of 2002. On July 1, 2002, after three days of rain across the Upper Guadalupe River Basin, Canyon Dam's reservoir waters began to rise. By 4 p.m. on July 1, reservoir levels had risen 5 feet. The rain continued to fall across the Upper Guadalupe River Basin. By July 3, reservoir levels had risen to just 10 feet below the spillway.

The lip of Canyon Dam sits 974 feet above sea level. It is an earthen dam which works well as long as water does not spill over the top, or undermine the base. To prevent this, a 10-foot release tunnel below the dam allows up to a maximum of 5,000 cubic feet per second (cfs) to be released downstream. The Canyon Dam tunnel typically releases a constant 300 to 500 cfs downriver. Ultimately over 67,000 cfs would flow out of the lake.

As further protection to the earthen dam, a spillway was created. It is excavated limestone more than 1,000 feet wide. The spillway route follows the downward slope of a small wooded valley for about a mile and a half before it crosses under an access road. The spillway route continues for another mile beyond this road as a wider drainage before it finally meets the Guadalupe River below the dam. This spillway allows lake water to "spill" out of the reservoir should water levels exceed 943 feet above sea level. This a difference of 31 feet between the spillway and the top of the dam. Prior to July, 2002, this spillway had never been used.

As rains continued to fall, the reservoir level reached 938 feet in the early morning hours of July 4, just 5 feet below the spillway. Homes and businesses were evacuated. By 3:30 p.m. the reservoir water levels exceeded 943 feet and the water began to go over spillway. Water flooded the limestone slab, ran the 2.5-miles down the natural spillway and entered the Guadalupe River below. The rain continued to fall.

Reservoir levels continued to rise, exceeding 950 feet. It is estimated that over 300,000 cubic yards of rock and soil were carried the 2.5 miles down to the spillway to the Guadalupe River. 1-1/2 to 3 times the amount of water stored in the lake (at normal level) went over the Spillway during the flood event.

Water continued to flow over the Spillway for approximately 6 weeks. Rocks, trees, logs, and other flood debris piled up in the Guadalupe River and created a huge blockage. Flooding continued from the dam to the Gulf Coast.

Over the space of three days the rushing water gouged out a canyon 1.5 miles long and up to 80 feet deep. This canyon now sits behind the emergency spillway of Canyon Lake.

Fossils Revealed