Thursday, May 22, 2014

Barton Springs Above Drought Threshold, Lovelady Below

Stage II Alarm Drought
Barton Springs discharge: 50 cfs 10-day average
Lovelady Monitor Well: 474.00 ft-msl

Barton Springs saw a surge in flow after last week's rain, causing a momentary reversal to the trend of decreasing discharge that has been the norm since late last year. As welcome as that change is, the increased flow is not due to a dramatic increase in water storage in the aquifer, but more to do with how well connected Barton Springs is to conduits and fractures that quickly carry water to it from recharge features in creek beds. Substantial recharge to the aquifer occurs when there is prolonged flow in the creeks; last week's rains only generated runoff for a brief period and thus, only minimal recharge. The increased flow at Barton springs has already peaked and is once again trending downward. The District's other drought trigger site, Lovelady monitor well, is not as well connected to conduits and fractures like Barton Springs, and as such is not susceptible to sudden water level rises. The hydrograph for Lovelady monitor well did not experience a sudden change like Barton Springs did, rather, it has just flattened out momentarily. See the most recent Drought Status Chart here. Even though flow at Barton Springs has increased and is well above its Stage II drought threshold, a drought declaration remains in place because Lovelady monitor well is below its threshold of 478.4 ft-msl. With any luck ENSO conditions will develop before too long. The Climate Prediction Center expects that chances of El NiƱo conditions developing during the summer exceed 65%.

No comments: