Overview
Water age and thermal structure of Lake Mead were modeled using the three-dimensional hydrodynamic Environmental Fluid Dynamics Code (EFDC). The study aimed to understand how lake circulation responds to significant drawdown should drought conditions persist.
Model Setup
The model was calibrated using observed data from 2005 and then applied to simulate two scenarios: a high-stage scenario with an initial water level of 370.0 m, describing predrought lake hydrodynamics, and a low-stage scenario with a projected initial water level of 320.0 m, projecting lake circulation under significant drawdown.
Key Findings
The results indicate that water level drawdown plays an important role in thermal stratification and water movement during receding water levels, with the impact most significant in shallow regions such as Las Vegas Bay. Depth-averaged water temperature in the low-stage scenario was estimated to increase by 4–7 °C in shallow regions and 2–4 °C in deep regions, while depth-averaged water age decreased by about 70–90 days for shallow regions and 90–120 days for deep regions. Such changes in temperature and water age due to continuous drought would strongly influence the hydrodynamic processes of Lake Mead, and the study provides a numerical tool to support adaptive management of regional water resources.