Thursday, May 7, 2015

Welcoming the Rain, Hoping for More in the Edwards' Recharge Zone

No drought
Lovelady well height: 498.71 ft-msl
Barton Springs: approximately 92 cfs 10-day average

Tuesday, May 5, brought heavy rainfall to areas throughout Central Texas. While central Texans typically welcome rain as a much-needed event, the specific locations that receive the rain impact the Barton Springs segment of the Edwards aquifer differently. Northern Travis County experienced flash flooding as a result of the rain with Bull and Walnut Creeks experiencing over 4,000 cubic feet per second (cfs) according to LCRA flow stations. We can generally say that significant recharge occurs when Onion Creek (in Southern Travis & Northern Hays counties) is flowing all the way across the recharge zone to Antioch Cave. However, Hays County received very little rainfall by comparison. Creeks within the critical recharge zone like Onion, Slaughter, Bear and Little Bear saw small increases in flow. For example, flow in Onion Creek (at Driftwood) rose from 25 cfs to 35 cfs from the rains. Antioch cave, the largest-capacity recharge feature in Onion Creek near Buda, did not receive any creek flow or recharge.

The Edwards Aquifer recharge zone provides direct inlets for recharging the aquifer. When rain falls in the watershed upstream of this critical area, especially in northern Hays County, streamflow provides sustained recharge to features like Antioch Cave and other sinkholes, which act as conduits directly into the aquifer. As a result, the water supply is bolstered and habitats for critters like the Barton Springs salamander are maintained.

Although the recharge was not significant to the aquifer as a whole, all things considered, Tuesday night’s rain helped keep Barton Springs flowing for Austin’s summer bathers and provided needed thirst-quenching for local plants and wildlife. The rains also helped continue the rise in groundwater levels seen in the Lovelady monitor well. For the year, the Austin areas is 0.3 in above average for rainfall. Less than a week into May, we’ve received almost a fourth of the month’s historical rainfall (0.97in of 4.4in) according to the BSEACD station. Let’s hope the rains continue to visit Central Texas and the Edwards Aquifer recharge zone is not left out.
The outlook for future rainfall looks promising as the National Weather Service Climate Prediction Center anticipates that with the wet start to the month across the plains, forecasts indicate an active southern stream and a generally wet pattern for much of the United States.

And to folks who encounter flash flooding, remember it’s always safer to turn around at flooded low water crossings!

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