Flash Flood

As the world watches, with sadness, the news of the flooding in Houston from Hurricane Harvey, I am reminded of another Texas flood that severely damaged a Texas city. This flood wasn’t from a hurricane exactly, but rather like Harvey, the flooding occurred because of too much rain for the ground to handle. Early that September, the remnants of a Category 1 hurricane brought heavy rains to areas of Mexico, as well as the state of Texas, particularly in the San Antonio area. On September 4, a tropical cyclone had developed in the southwestern Gulf of Mexico near the Bay of Campeche. It moved slowly in a general westward direction. Then, the storm reached hurricane intensity on September 7 prior to making landfall south of Tampico, Mexico the following day. The storm weakened over land, and lost cyclonic characteristics later that day, but a nearby high-pressure area forced the remnants of the system northward into Texas. So it was that was on September 7, 1921 in San Antonio, Texas, after some of the heaviest rainfall ever recorded in Texas…at least up to that time…dumped an astounding 23.11 inches of rain in the San Antonio area in less than a day.

In some areas of Texas, the rainfall was even worse, but those areas somehow didn’t have the same potential for devastating floods. The precipitation peaked over Central Texas, where the highest rainfall amount measured was 40 inches near Thrall, Texas. This was the fourth highest tropical cyclone-related rainfall total in Texas since record keeping began. Similarly, an observation of 36.40 inches elsewhere in Williamson County, Texas ranked as the sixth-highest tropical cyclone-related rainfall total for the state. The high precipitation totals set nationwide records which would stand for several years. Like Hurricane Harvey, that storm stalled and the rain just kept coming.

The immense amount of rain quickly overwhelmed the San Antonio River that winds through southwest Texas. The area is usually pretty dry, but on that September day, the storm that stalled over Taylor, Texas was a recipe for disaster. It was the heaviest single day of rainfall in the state to that time. Taylor is located 30 miles upstream from San Antonio, so when the flash flood came barreling down, it took aim on San Antonio with a vengeance. Most of the 51 flood victims were trapped in their cars by the surprise flood and drowned. Much like Houston, five to ten feet of water submerged the city’s streets, delaying an evacuation. The city was under water for nearly a week following the flood. The flood damage amounted to at least $5 million in damages in the small city that was San Antonio, at that time. In the aftermath, San Antonio embarked on a 10 year overhaul of its levee system, not knowing for sure that it would really help, but I guess they did what they knew to do.