Investigating Uncertainty of Groundwater/Surface-water Interactions in the Lower San Antonio River Basin, Texas

Monday, December 4, 2017: 2:50 p.m.
Linzy Foster , Texas Water Science Center, U.S. Geological Survey, Austin, TX
Jeremy White , US Geological Survey WRD Texas Water Science Center, Austin, TX

The quantification of model uncertainty provides important information regarding a model’s ability to predict a quantity of interest. Linear-based First-Order Second-Moment (FOSM) analysis is a technique that yields initial estimates of model predictive ability, also referred to as model reliability. In this study, a novel groundwater/surface-water model of the lower San Antonio River basin and surrounding areas is in development and is being paired with FOSM analysis to quantify the uncertainty surrounding simulated groundwater/surface-water exchange. In light of recent drought conditions, a predictive drought scenario of streamflow response to reduced rainfall and increased groundwater withdrawals will be investigated. The study’s main goal is to develop a tool that can assess spatial and temporal variations in flow occurring between the lower San Antonio River (and its major tributaries) and underlying aquifer units these streams traverse during 2006 through 2013. The modeling analysis may indicate reaches with potential for streamflow depletion within the basin. FOSM analysis is being applied through the use of PEST++ and pyEMU. Observations include groundwater levels within the Texas coastal uplands and Texas coastal lowlands aquifer systems and groundwater contributions to base flow in main-stream reaches. The results of this analysis will include simulated volumetric surface-water totals with associated uncertainty at the confluence of the San Antonio and Guadalupe rivers, which will provide improved understanding of how streamflow is affected by groundwater pumping within the basin.
Linzy Foster, Texas Water Science Center, U.S. Geological Survey, Austin, TX
Linzy Foster is a Civil Engineer with the U.S. Geological Survey, based in the Texas Water Science Center Austin office. She has a B.A. in Mathematics and a M.S. in Civil Engineering. Her research focuses on groundwater modeling and the application of uncertainty analysis to groundwater models.

Jeremy White, US Geological Survey WRD Texas Water Science Center, Austin, TX
Dr. Jeremy White is a hydrologist and groundwater specialist with the Texas Water Science Center in Austin, Texas. He completed his B.S. in computer science at West Texas A&M, and M.S. and Ph.D. in geology at the University of South Florida. Dr. White has extensive experience with parameter estimation and uncertainty quantification in environmental and geophysical models, as well as simulation of surface water and groundwater interactions and density-dependent groundwater flow. Dr. White also has experience using high-performance computing systems to solve massively and embarrassingly parallel problems.

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