Tuesday, January 12, 2016

Edwards and Trinity Aquifer conditions, A Year In Review

No Drought
Lovelady well height: 524.60 ft-msl
Barton Springs: approximately 104 cfs 10-day average

          2015 began with some much-needed relief from Stage II Alarm Drought conditions. After rejuvenating rainfall in the preceding months, the Board declared No-Drought on January 29. Fueled by a stronger-than-usual El Niño phenomenon, heavy rainfall continued throughout the spring. A brief dry spell in summer was quickly overtaken by even heavier rains in the fall.  In a nutshell, 2015 was a wet, then briefly dry, then even wetter year.

          Steady recharge increased water levels in the Edwards and Trinity aquifers as well as Barton Springs and Jacob’s Well flow early in 2015. Aquifer levels continued an upward trend and received an even larger boost from extremely heavy rainfall on Memorial Day, as 5.20 inches fell on Camp Mabry. Total May rainfall in Austin reached a record-breaking 17.59 inches, topping the previous tally of 14.10 inches in 1895. The Hill Country and San Marcos received between 12 -15 inches. Rain temporarily disappeared from the region in July and August to round out the summer.

          Central Texas became perhaps more familiar than ever with the El Niño phenomenon, as 2015 boasts one of the strongest in history. As a result, the dry spell of summer was short-lived. An historic Halloween flood unleashed an astounding 18.5 inches in Buda, with surrounding areas reporting between 11 and 16. This event topped the previous Halloween 2013 and Memorial Day 2015 floods in stage level and discharge on Onion Creek. Antioch cave began taking desired recharge after storm runoff flows passed.

          In the 2015 Hydrograph (above, click to enlarge) includes three graphs depicting periods of above and below average rainfall at Camp Mabry during 2015 and the resulting effects on the Lovelady monitor well  and Jacob’s Well spring. At periods of above average rainfall, visible in the lowest graph, the discharge level at Jacob’s well spikes dramatically. Throughout the year, and at accelerated rates after rain events, the Lovelady Monitor well depth to water slowly increased.

          After continued rains through the 2015 Holiday Season, Texas remains drought-free as of January 5. The Lovelady well and Barton Springs drought trigger sites remain well above their respective average thresholds. The outlook for 2016 according to the National Oceanic and Atmospheric Administration is a still strengthening El Niño that could last into early spring. This perhaps being the strongest El Niño since 1997-1998.

On behalf of the BSEACD, Happy New Year!

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