Numerical groundwater models for Edwards Aquifer systems

Abstract

Numerical models have been an integral component in management of the Edwards Aquifer for over four decades. The scale and complexity of the models have varied considerably during this time, with the changes attributed to improvements in both numerical software and the conceptual models on which the models are predicated. Resolution of early models was coarse, which rendered them useful only in large-scale, groundwater-resource assessments. Increased resolution and improved refinement in the conceptualization of the complex hydrostratigraphic framework of the Edwards Aquifer have led to expanded applicability of the ensuing models in terms of accommodating local-scale hydraulic features such as pumping scenarios and changes in recharge/discharge mechanisms (i.e., urbanization and climate change). As part of these improvements and advancements, regional-scale groundwater availability models augmented by local-scale models based upon improved conceptualization provide the ability to: (1) replicate more extreme conditions, such as the drought-of-record; (2) improve boundary conditions by extending models to include natural hydraulic boundaries; and (3) couple groundwater flow models with surface-water flow models so that the entire terrestrial water cycle can be accommodated during water-resource management scenario assessment.

Hydrogeochemical Evaluation of Aquifer Storage and Recovery in Edwards Aquifer, New Braunfels, Texas

“…Previous studies include numerical models of groundwater flow (Maclay and Land 1988;Scanlon et al 2003;Lindgren et al 2004;Green et al 2019), Edwards aquifer hydrogeology and management (Maclay 1989;McKinney and Watkins 1993), aquifer sedimentology, stratigraphy, aquifer matrix permeability, and porosity, karst, and fracture porosity (Maclay and Small 1983;Hovorka et al 1994Hovorka et al , 1995Hovorka et al , 1998, diagenetic studies (Ellis 1985;Hovorka et al 1994;Choquette and Hiatt 2008), and the hydrochemistry of the Edwards (Pearson Jr. and Rettman 1976;Maclay et al 1980;Clement and Sharp Jr. 1987;Oetting et al 1992;Oetting et al 1996;Sharp Jr. and Smith 2019). Integration of the results of these studies conducted mostly in the freshwater zone improved hydrogeological and hydrogeochemical models of the Edwards aquifer.…”

The Edwards Aquifer

“…There are recognized limitations and shortcomings in all numerical groundwater models, such as the particular modeling software selected, uncertainty about the underlying conceptual model and its implementation in the ensuing numerical model. Nonetheless, models are the preferred tool for groundwater resource management (De Marsily, 1986;Anderson and Woessner, 2015;Scanlon et al, 2003;Hartmann et al, 2014;Green et al, 2019d).…”