Khorrami et al. (2025) Drought-induced changes in groundwater-surface water exchange at Lake Mead area

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-12-01
• Authors: Mohammad Khorrami, Susanna Werth, Sonia Zehsaz, Manoochehr Shirzaei
• DOI: 10.1016/j.ejrh.2025.102996

Research Groups

• Department of Geosciences, Virginia Tech, Blacksburg, VA, USA
• United Nations University Institute for Water, Environment and Health, Hamilton, ON, Canada
• College of Engineering, Oregon State University, Corvallis, OR, USA

Short Summary

This study investigates the hydrological response of the coupled surface-groundwater system to the 2020–2022 drought in the Lake Mead region using InSAR and elastic load modeling. It quantifies significant total water storage loss, including substantial groundwater depletion, and reveals hydraulic connectivity between the lake and aquifers, emphasizing the need for integrated water management.

Objective

• To determine if drought-induced mass loss produces measurable elastic uplift detectable by geodetic observation.
• To quantify if groundwater withdrawal represents a substantial component of the total water-storage decline during the drought.
• To assess if groundwater level changes lag lake-level variations due to delayed lateral pressure diffusion within the aquifer system.
• To evaluate if, under extreme drought conditions, groundwater depletion is directly driven by surface-water loss, reflecting strong hydraulic connectivity and underscoring the need for integrated management of both resources.

Study Configuration

• Spatial Scale: Lake Mead region in the southwestern United States, focusing on a 3150 km² area surrounding the lake.
• Temporal Scale: The 2020–2022 drought period, with InSAR observations specifically from April 6, 2020, to July 7, 2022.

Methodology and Data

• Models used:
  • Inverse elastic load modeling framework (half-space approach)
  • Continuous Wavelet Transform (CWT) for time-frequency analysis (using Derivatives of Gaussian wavelet)
  • First-order pressure diffusion model
  • North American Land Data Assimilation System (NLDAS) land surface models (Mosaic, Noah, VIC) for soil moisture
• Data sources:
  • Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) data (C-band, descending path 173, 111 images)
  • U.S. Geological Survey (USGS) groundwater level data (daily and field archives)
  • Arizona Department of Water Resources (AZDWR) groundwater level data (transducer and field archives)
  • NLDAS soil moisture storage datasets
  • SNODAS (Snow Data Assimilation System) snow storage datasets
  • California Department of Water Resources’ California Data Exchange Center (CDEC) Lake Mead volume
  • U.S. Bureau of Reclamation (USBR) Lake Mead daily water levels
  • U.S. Drought Monitor (USDM) data
  • Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (1-arcsecond, ~30 m)
  • Nevada Geodetic Laboratory GNSS station rates (MIDAS Velocity Fields in IGS14 reference frame) for validation

Main Results

• Detected ground uplift of up to 8 mm/yr near the lake center, attributed to crustal rebound from reduced water-mass loading.
• Estimated total water storage (TWS) loss at 3.03 ± 0.25 km³/yr across a 3150 km² area surrounding Lake Mead (using an Elastic modulus of 300 MPa).
• Groundwater storage change (GWSC) accounted for approximately one-third of the TWS loss, estimated at 0.94 ± 0.32 km³/yr (using an Elastic modulus of 300 MPa).
• Observed time lags of 6–98 days between lake and groundwater level responses, suggesting hydraulic connectivity.
• Calculated lateral diffusivity values ranging from 3.2 m²/s to 86 m²/s (mean = 40.5 m²/s; median = 38 m²/s).
• Lake Mead's water level declined by 17 m (from 335 m to 318 m above mean sea level) during the study period, corresponding to a total volume loss of approximately 4 km³.
• The optimal Elastic Modulus for the region is considered to be approximately 250 MPa, yielding TWS/GWS estimates that align with independent GWS estimates based on aquifer storativity and groundwater level changes.

Contributions

• Quantified total water storage losses around Lake Mead during the 2020–2022 drought and specifically determined the share attributable to groundwater depletion.
• Demonstrated the feasibility and robustness of inverting Sentinel-1 InSAR-derived elastic uplift to estimate basin-scale, drought-driven water storage variations.
• Extracted and interpreted characteristic time lags between lake-level and groundwater-level changes to infer hydraulic connectivity and lateral diffusivity.
• Evaluated how these coupled responses inform integrated water-management strategies for stressed aquifer–reservoir systems during extreme climate events.

Funding

• U.S. Department of Energy (DOE)
• National Aeronautics and Space Administration (NASA) (Grant 80NSSC21K0061)

Citation

@article{Khorrami2025Droughtinduced,
  author = {Khorrami, Mohammad and Werth, Susanna and Zehsaz, Sonia and Shirzaei, Manoochehr},
  title = {Drought-induced changes in groundwater-surface water exchange at Lake Mead area},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102996},
  url = {https://doi.org/10.1016/j.ejrh.2025.102996}
}