The Role of Teleconnections in Hydrologic Drought for the Texas Hill Country

Abstract:

The Highland Lakes are six lakes on the Colorado River in the Texas Hill Country. The Lower Colorado River Authority (LCRA) operates the lakes, which were completed in 1951. The Highland Lakes provide water supply to municipal, industrial and agricultural users, and environmental flows for the river and Matagorda Bay. In Central Texas, 1.4 million people depend on the reservoirs as their primary water supply. From 2011 to 2015, the Highland Lakes experienced a severe hydrologic drought resulting in a new drought of record for the river basin. This drought replaced the previous benchmark drought of the 1950s. Both of these benchmark droughts exhibit similar contributions to drought development, persistence and amelioration due to influences of the Pacific Decadal Oscillation, Atlantic Multi-decadal Oscillation and the El Niño Southern Oscillation. We show that the concurrence of specific phases of each of these teleconnections contributed to the severity of the benchmark droughts while lesser droughts have lacked the unfavorable impacts of each of these influences. Furthermore, we present the statistical significance of these teleconnections’ concurrence to persistent low streamflow in the region. We also explore the ability to evaluate situational awareness of persistent drought potential using these the status of these teleconnections.