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!

Thursday, March 26, 2015

Creeks Flowing, Groundwater Rising in our Area

No Drought
Lovelady: 492.1 ft-msl
Barton Springs: approximately 92 cfs 10-day average


Groundwater levels continue to rise thanks to the overall rainy conditions experienced in March. Many area streams that flow over the recharge zone of the Barton Springs segment of the Edwards aquifer have seen several periods of prolonged flow, thus providing a relatively steady input to the groundwater supply. Except for one week in December, Barton Creek has been flowing since late November 2014. According to the USGS Onion creek gauge near Driftwood, TX, flow in the creek has not dropped below 20 cfs since the end of December. As it flows east over the Barton Springs Edwards aquifer recharge zone, Onion creek steadily loses water to the aquifer via fractures and karst features located in the creek bed, and by the time it gets to the eastern edge of the recharge zone, has lost all of its water to the aquifer. 

Despite the overall good conditions in the Barton Springs segment of the Edwards aquifer, it is important to remember that other parts of the state are still under severe drought and the we are very much at the mercy of where and when the rain falls. For instance, many of the lakes in the Highland lake system are far below their full capacity and the Edwards Aquifer Authority has a drought declaration in place. 

Thursday, February 26, 2015

Aquifer Still Recharging

No Drought Status
Lovelady monitor well: 486.6 ft-msl
Barton Springs: 78 cfs 10-day average

District staff visited a tract of land in the recharge zone of the Barton springs segment of the Edwards aquifer with access to Onion Creek. Staff conducted two flow measurements about 1.5 miles apart. The upstream measurement was of 25 cfs, while the downstream measurement was of 4 cfs. The difference between the amount of flow at the two locations is due to a number of important karst features in the creek bed that are providing water to the aquifer, thus recharging groundwater.

Below see the hydrograph for Lovelady monitor well which shows water levels continuing to rise.


Thursday, February 12, 2015

Out of Drought Conditions, Water Levels Continue to Rise

No Drought
Lovelady monitor well: 483.4 ft-msl
Barton Springs 10-day avg discharg: 82 cfs

On January 29th the District Board of Directors voted to end the drought declaration that had been place since August last year. The last few months of 2014 brought with them fairly consistent rain and cold winter temperatures which minimized water lost to evapotranspiration. These conditions were prime for generating runoff and sustained flow in the creeks where most of the recharge to the Barton Springs segment of the Edwards Aquifer occurs. As a result, water levels in the aquifer have been on the rise since mid-November. Almost 5.5 inches of rain fell at the District office in January, continuing the wet trend seen towards the end of 2014 and further contributing to recharging the aquifer. Flow at Barton Springs appears to be peaking at around 82 cfs, whereas Lovelady monitor well water level continues to rise. The Climate Prediction Center places a 50-60% chance El Niño conditions developing during the remaining winter months of 2015, which generally mean wetter conditions in central Texas. Fortunately, we have been able to exit drought even without the help of an El Niño.  While it’s nice to have aquifer levels above drought levels and for groundwater users to be relieved of drought restrictions for a while, one look at the highland lakes shows that drought conditions remain of looming concern here in central Texas.
 

Thursday, January 22, 2015

Over Night Soaking has Creeks Flowing

Stage II Alarm Drought
Lovelady monitor well: 475.85 ft-msl
Barton Springs discharge: 68 cfs 10-day average

The rain that started yesterday afternoon and fell steadily through much of last night and today has generated substantial runoff and as result, all of the area creeks are flowing. The catchment areas for the creeks responsible for much of the recharge to the Barton Springs Segment of the Aquifer, that is Onion, Bear, Slaughter, Williamson, and Barton creeks, received between about 2 to 3.5 inches over the last 24 hours, and forecasts place the chance of rain tomorrow upwards of 70%. Preceding this rain event, soils already had a high moisture content, thus conditions were prime for generation of runoff. Groundwater levels, for their part, have been on the rise since November and this rain will certainly help continue that trend, possibly even bringing water levels above the drought threshold of 478.4 ft above sea level over the course of the coming days or weeks, but that remains to be seen. 

Thursday, January 15, 2015

NWS: 2014 Cooler, Wetter than Average

Stage II Alarm Drought
Lovelady monitor well: 474.4 ft-msl
Barton Springs discharge: 67 cfs 10-day average

The National Weather Service put out their climate summary for the year 2014 in central Texas based on observations at Austin's Camp Mabry. According to the summary, Camp Mabry received 1.21 inches more rain for the year than the normal 34.22 inches and experienced temperatures 0.3 degrees Fahrenheit cooler than average. The temporal and spatial distribution of precipitation events that were able to produce groundwater recharge, caused groundwater levels to vacillate up and down, while generally exhibiting a descending trend for much of the year (see figure). Since early November 2014 groundwater levels have been on the rise and it remains to be seen whether they will rise above the Stage II Alarm threshold without more recharge. 


Thursday, January 8, 2015

Groundwater Levels Continue Fluctuating

Stage II Alarm Drought
Lovelady Monitor Well: 472.99 ft-msl
Barton Springs: 55 cfs 10-day average

The timing and magnitude of the rains over the fall and winter months have led to a continuation of odd water level oscillations that have characterized the Lovelady monitor well hydrograph over the past year (see Image). Since big rains at the end of November (the District office received over 4 inches over the course of 2 days) groundwater levels have been rising but appear to be tapering off. Currently, conditions are good for the rains predicted for this weekend to generate runoff in the creeks that flow over the recharge zone. Barton Creek is the only area creek that is presently flowing at a substantial rate, but if the rain causes flow in the other creeks it may boost water levels in the aquifer. 

Thursday, December 11, 2014

Groundwater Levels Continue Vacillating

Stage II Alarm Drought
Lovelady monitor well: 471.7 elevation ft-msl
Barton Springs: 62 cfs 10-day average

The trend of rollercoaster-like rise and falls in groundwater levels this year continues as big rains in November generated enough surface runoff to cause many of the creeks over the recharge zone of the Barton Springs Segment of the Edwards aquifer to flow for a few days. Barton Creek has been flowing continuously, albeit at a decreasing rate, since November 21st and 22nd over which period some areas received upwards of 5 inches of rain (4.25 inches at District offices). As a result, both Barton Springs and Lovelady monitor well (district drought trigger sites) experienced sudden rises in their hydrographs. Currently, Barton Springs discharge has started falling after reaching a maximum 10-day average of 65cfs; Water level in Lovelady monitor well continues to rise. According to District rules, both drought triggers sites must be above their respective drought thresholds for a drought declaration to be lifted. It is unlikely that the Lovelady well water level will rise above the 478.4 ft-msl Stage II Alarm Drought threshold before peaking, but that remains to be seen. The season's cool temperatures and cloudy weather improve the odds that any rain we do get will have a better chance of generating considerable amounts of recharge. The Climate Prediction Center has increased the likelihood it places on the development of ENSO conditions for this winter to 65% and expect it to last into spring 2015.

See the District's latest official Drought Chart here: http://www.bseacd.org/aquifer-science/drought-status/

Tuesday, November 25, 2014

Welcome Soaking over the Weekend

Stage II Critical Drought
Lovelady: 466.68 ft-msl
Barton Springs: approximately 35 cfs 10-day average

The rain over the weekend was substantial enough to create flow in area creeks where the majority of recharge to the Barton Springs Segment of the Edwards Aquifer occurs. Hopefully these rains are the precursor to the wet conditions possible with the arrival of El Niño conditions which the National Weather Service places a 58% chance of developing during winter 2014-2015 and lasting into spring 2015. Although Barton Springs experienced a sudden increase in flow due to the rain over the weekend, that increase does not indicate an increase in groundwater storage in the aquifer, rather a sudden surge of surface water travelling quickly through developed karst conduits (caves, sinkholes, etc). Lovelady monitor well hydrograph, the District's other drought trigger site, has slowed its descent into deeper stages of drought for the time being and may be indicating a subtle rise in aquifer water levels due to the rain, but whether that is the case or not remains to be seen. To see the latest official District drought status click here

Thursday, November 20, 2014

Rain in November Average

Stage II Alarm Drought
Lovelady monitor well: 468.7 ft-msl
Barton Springs: 35 cfs 10-day avg.

Total rainfall at the district office in November of 3.2 inches was just shy of the historic average for the month of 3.3 inches. This ahead of the 58% chance NOAA's Climate Prediction Center places on El Nino (ENSO) conditions developing this winter and extending in spring 2015. ENSO conditions generally correlate with wetter periods in central Texas. Currently, despite the average rain conditions recharge to the aquifer has been minimal and consequently water levels in the aquifer are declining after a summer of roller-coaster-like ups and downs (see drought chart here).