This spring Central Texas has received heavier than normal rainfall. April was the 9th wettest month on record since 1897 for Austin, and the wettest since 1976. In the first two weeks of May alone, 7.14 inches of rainfall has been recorded. Normally Austin gets about 4.44 inches for the whole month.
In fact, since April 1st, state rainfall amounts are double the average. The U.S. Drought Monitor, a consortium of academic and government researchers, now considers 96.95 percent of Texas drought-free. One year ago, only 40 percent of the state was considered to be drought-free.
A weak El Niño ocean pattern is probably contributing to the unusually heavy rainfall. It’s similar to the one connected with the destructive flooding in May 2015, when more than 17 inches of rain fell in Austin — an all-time May record. This Pacific El Niño pattern is predicted to continue throughout the summer, and possibly into the fall.
The heavy rainfall in May caused flash flooding in Hays and Travis Counties, including the city of Austin, making hundreds of low water crossings impassable. Many people who tried to cross the high water had to be rescued.
Austin Parks and Recreation Department also closed the following due to the severe weather:
- Barton Creek Greenbelt and the Barton Springs Pool
- Ann and Roy Butler Hike and Bike Trail
- Red Bud Isle Park and Trail
- Zilker Zephyr Train in Zilker Park
- Shoal Creek Trail
These have since reopened, with the exception of the Zilker Zephyr Train, and the Shoal Creek Trail. The Trail was damaged by a landslide resulting from heavy rain and won’t be open until early 2020.
As well, the upper part of Lake Austin from Mansfield dam to Commons Ford Park, and the lower part of Tom Miller dam to Walsh Boat Landing, were shut down. Lady Bird Lake was closed entirely. All commercial boating was banned, with the exception of motorized commercial watercrafts with a length of 40 feet or more, on Lake Austin between Walsh Boat Landing and the Loop 360 Bridge. Nighttime recreational boating on a portion of north Lake Travis near the confluence with the Pedernales River was also banned.
These lakes have all reopened, and all the bans have been lifted. The Lower Colorado River Authority (LCRA) is telling boaters, however, to continue to use caution on Lake Travis and throughout the Highland Lakes. Numerous floodgates, which had been open along the Highland Lakes to move storm runoff downstream, are now all closed as of May 17th.
Flash Flood Alley
The Hill Country and Central Texas region is called Flash Flood Alley because it has a greater risk of flash flooding than most regions in the United States. This area has shallow soil, a steep terrain, and unusually high amounts of rain. Such heavy rainfall quickly turns into fast-moving walls of water that are very destructive.
According to Austin’s Watershed Protection Department, “Austin lies in the heart of Flash Flood Alley”. Floods can happen at any time, so the City recommends taking the following steps during a storm to stay safe:
- Be aware of your surroundings.
- Check with local media.
- Don’t drive.
- Avoid creeks, ponds, trails, culverts, and other drainage systems.
- Seek higher ground if water starts to rise (e.g. your roof).
Driving During a Storm
About 75 percent of flood-related deaths in Texas occur in vehicles. During heavy storms it’s difficult at night to see if a road is flooded. Survivors have said they didn’t see the flood until their vehicle stalled in the high water.
Not all flooded roads will be barricaded, so take the following safety measures:
- Steer clear of low water crossings.
- Be alert for water on the road.
- Go to ATXfloods to check for known flooded roads.
- Register at WarnCentralTexas for weather warnings and other emergency alerts.
- If you see water over the road, or a barricade, turn around. The road can also be heavily damaged under the water.
Atlas 14 Study
Atlas 14 is a study conducted by the National Oceanic and Atmospheric Administration (NOAA) and is the first of its kind since 1961. It’s a reassessment of historic rainfall intensities for Texas, and it shows the Austin area is likely to flood more frequently than previously thought.
The belief before the study was that there was a 1 percent chance in any given year that there would be 10.2 inches of rainfall in Austin during a 24-hour period. This was the official definition of the 100-year storm. The Atlas 14 study shows the new 100-year storm would be closer to 13 inches of rain in some parts of Austin, which resembles the current 500-year storm. Redefining the 100-year storm means that many more homes and businesses could flood than previously thought. There’s also increased risk to homes and businesses already known to have flood risk.
There are many other impacts of the study:
- The number of buildings in the 100-year floodplain (area of land likely to be under water when the creek rushes over its banks — the full extension of the creek) will increase approximately from 4,000 to 7,200. Residents with federally-backed mortgages will have to buy insurance, as well as any affected businesses. Those already at risk will see increased costs.
- Changes to the City code, aimed at preventing future flooding problems in the 100-year floodplain, will limit new development for more property owners. Homeowners who wish to make improvements to their houses will also be impacted.
- Bridges, storm drain pipes, detention ponds, and other drainage structures are not large enough to handle the increased rainfall, possibly resulting in the flooding of businesses, homes, and roads.
- Austin’s two floodwalls aren’t designed for the new 100-year storm.
Is Your Property Affected?
The City of Austin has an Atlas 14 flood risk section where you can find a link to a map of the interim 100-year floodplain, and instructions on how to discover if your property is in the redefined 100-year storm area. You can even print and download a map of your property if located in the floodplain.
Rain and Your Sprinkler System
Needless to say, when it’s raining, you should turn your irrigation controller to the “off” position. More sophisticated controllers have a “rain delay” setting that allows you to turn off the irrigation system for a specific number of days, without having to remember to turn it back on. This also gives the soil time to dry out after heavy rainfalls over an extended period.
Many irrigation systems also have rain or soil moisture sensors installed (or both) that prevent watering when moisture is detected. These will also stop overwatering if you turn your system back on too soon and the soil’s still too wet, or it starts raining again. The average Texas lawn only needs about an inch of water weekly in the warmer weather. Watering deeply two to three times a week, rather than daily, will give your grass a deep root system, making it stronger and more drought-resistant.
Call South Austin Irrigation, your trusted sprinkler repair and maintenance specialists, at (512) 534-7449 for your irrigation needs or complete our online service request form.