USGS Stream Gage on Onion Creek at Twin Creeks Road:
Halloween 2013: Gage Height: 20ft; Discharge: 12,000 cfs
Memorial Day 2015: Gage Height: 22ft; Discharge: 17,000 cfs
Halloween 2015: Gage Height: 28ft; Discharge: 45,000 cfs
In Buda, the final rain total reached an astounding 18.46 inches. Surrounding areas, including Kyle, San Marcos, Wimberley and Onion Creek all reported between 11” and 16”. In addition to punishing rain totals, the storm generated three tornadoes and a great deal of property damage.
What made this flood so much more significant than the aforementioned 2013 and ‘15 events? In this case, huge amounts of rainfall were concentrated in a shorter period of time. In addition, the ground in Central Texas was relatively dry prior to this year’s Halloween flood than the months preceding the two earlier events. In dryer conditions, heavy rain doesn’t immediately infiltrate below ground; rather, there is a kind of shock from sudden intense rainfall which results
in surface flow rather than penetration. Potentially-devastating flash floods are sure to follow.
On the other hand, the Highland lakes saw significant rises in water level, counter to perennial dread about its historical low water levels. Recharge to the Edwards Aquifer hit overdrive, as recharge sites like Anitoch cave (pictured below) submerged.
We recognize that this relief is accompanied by devastation. We’re grateful for the responders who helped evacuate those who experienced this downpour as a disaster. We send care and encouragement to those reeling from yet another assault on their homes and loved ones by extreme flood events.
For information on the response and resources available in Austin and surrounding areas, visit https://www.atxfloods.com.
In the wake of flood events, it may be necessary to take extra precautions like boiling drinking water from your private well. Take a look at https://www.fraserhealth.ca/media/Flood_PrivateDrinkingWater.pdf to find out more.