Using Production Well Behavior to Evaluate Risk in the Depleted Cambrian‐Ordovician Sandstone Aquifer System, Midwestern USA

Abstract

Depletion and contamination of shallow aquifers has increased globally due to growing population demand, development and urbanization, and the expansion of irrigated agriculture (Gorelick & Zheng, 2015;Konikow, 2015;Siebert et al., 2010;Wada et al., 2012). Long-term monitoring of groundwater levels, along with more recent observations of water storage changes using GRACE satellite data, show significant declines in the world's major aquifers such as the High Plains aquifer system (

What is a static head measurement? Evaluating structural error and implications for regional groundwater modeling

“…The initial steady state model calibration was conducted using the automated parameter estimation code PEST (Doherty, 2010) on predevelopment conditions (Meyer et al, 2009). Modern calibration has largely been an iterative process that involves analyzing data from production wells (Abrams, Roadcap, et al, 2018) and refining local complexities such as the Sandwich Fault Zone (Hadley et al, 2021). The circulation of water introduced by multi‐aquifer wells (MAWs) is handled using the Time‐Variant Material package in MODFLOW‐USG that is available in the graphical user interface Groundwater Vistas 7 (Rumbaugh & Rumbaugh, 2020), increasing vertical hydraulic conductivity in the general region where MAWs are present (Mannix et al, 2019).…”

“…The circulation of water introduced by multi‐aquifer wells (MAWs) is handled using the Time‐Variant Material package in MODFLOW‐USG that is available in the graphical user interface Groundwater Vistas 7 (Rumbaugh & Rumbaugh, 2020), increasing vertical hydraulic conductivity in the general region where MAWs are present (Mannix et al, 2019). This transient handling of MAWs is essential since the transition of constructing wells only open to the lower IG aquifer in recent decades changed vertical leakage and circulation of water within the sandstone aquifer system (Hadley et al, 2021; Mannix et al, 2019). It is also worth noting that the model calculates a head for each model layer that a well is open to, but our calibration is to the head from the IG Sandstone.…”

“…While sustainability is an important criterion for many planning agencies, owners and operators of high-capacity wells in northeastern Illinois typically have a planning horizon based on how long water can be extracted without supply issues. Hadley et al (2021) outlined the link…”

“…While sustainability is an important criterion for many planning agencies, owners and operators of high‐capacity wells in northeastern Illinois typically have a planning horizon based on how long water can be extracted without supply issues. Hadley et al (2021) outlined the link between declining heads in the sandstone system and the increased risk of high‐capacity wells failing to provide water demands. Based on empirical evidence from conversations with communities, wells are at‐risk of not being able to meet demands when static heads fall within 122 m (400 ft) above the top of the IG.…”

“…This region has always been modeled with MODFLOW, specifically utilizing MODFLOW‐USG (Panday et al, 2013) since 2018. As the available supply of water from the sandstone has become increasingly vulnerable as drawdown has increased, more accurate model calibration was required to make assessments of the remaining time pumping entities could extract water from the aquifer (Hadley et al, 2021).…”