Coupled analytical modeling of water level dynamics and energy use for operational well fields in the Denver Basin aquifers.

摘要

The South Metro Denver area in Colorado has been experiencing rapid growth in recent years and many municipalities in this region rely on the groundwater resources available in the Denver Basin as their chief water supply. As the population continues to increase, municipal water demands must be met with a sustainable approach. The Denver Basin aquifer system consists of four major aquifers that are composed of interbedded layers of sandstones, siltstones, and shales. The aquifers receive limited annual recharge and consequently the groundwater within them has the potential to be depleted. Declining water levels associated with groundwater depletion, interference between pumping wells, and fouling of wells is leading to losses in well productivity. Furthermore, declining water levels translates to higher electrical energy costs associated with water production.;Regional-scale numerical models developed for the Denver Basin aquifer system do not capture the local-scale drawdown about pumping wells, which is needed to effectively manage existing groundwater well fields. This research project utilizes production well data from the town of Castle Rock, Colorado to test the merits of using a Theis based approach to model water levels about production wells in the Denver and Arapahoe aquifers in Castle Rock. The model applies superposition of the Theis solution throughout both space and time to resolve the combined effects of pumping from multiple wells. This research demonstrated that the analytical method can be successfully applied as a predictor of continuous water levels at pumping wells. In addition, the analytical model provided a novel method for estimating aquifer properties using data from an operational well field, and it contributed a better understanding of the cross-well interferences that increase well drawdown. The model results were used to evaluate alternative pumping scenarios intended to reduce electrical energy costs associated with water production and increase sustainable yields from these aquifers. The alternative pumping scenarios achieved a net reduction in energy consumption ranging from 1.62% to 13.0% and led to a stronger conceptual understanding of how each aquifer responds to varying pumping conditions. This research demonstrates that the analytical solution modeling approach may be beneficial for application to many other projects involving groundwater supply management and optimization.