Groundwater depletion in California’s Central Valley accelerates during megadrought

Nature Portfolio (Springer Nature) | December 19th, 2022

Groundwater provides nearly half of irrigation water supply, and it enables resilience during drought, but in many regions of the world, it remains poorly, if at all mana

Groundwater provides nearly half of irrigation water supply, and it enables resilience during drought, but in many regions of the world, it remains poorly, if at all managed. In heavily agricultural regions like California’s Central Valley, where groundwater management is being slowly implemented over a 27-year period that began in 2015, groundwater provides two–thirds or more of irrigation water during drought, which has led to falling water tables, drying wells, subsiding land, and its long-term disappearance. Here we use nearly two decades of observations from NASA’s GRACE satellite missions and show that the rate of groundwater depletion in the Central Valley has been accelerating since 2003 (1.86 km3/yr, 1961–2021; 2.41 km3/yr, 2003–2021; 8.58 km3/yr, 2019–2021), a period of megadrought in southwestern North America. Results suggest the need for expedited implementation of groundwater management in the Central Valley to ensure its availability during the increasingly intense droughts of the future.

Groundwater Discharge by Evapotranspiration, Dixie Valley, West-Central Nevada, March 2009–September 2011

U.S. Geological Survey (USGS) | April 30th, 2015

Groundwater dominates snowmelt runoff and controls streamflow efficiency in the western United States

Nature Portfolio (Springer Nature) | May 3rd, 2025

Groundwater Exchange Pools and Urban Water Supply Sustainability: Modeling Directed and Undirected Networks

American Society of Civil Engineers (ASCE) | August 1st, 2018

Groundwater basins are important sources of water supply and storage for many cities. Groundwater exchange pools offer additional opportunities for utilizing these

Groundwater basins are important sources of water supply and storage for many cities. Groundwater exchange pools offer additional opportunities for utilizing these common pool resources, but their potential role in urban water management is not clear, and modeling such exchanges can be challenging. This paper presents an analysis of the potential for groundwater basin exchange pools to contribute to urban water supply sustainability. Building on an existing model of urban water management in Los Angeles, the analysis assesses the potential for groundwater exchange pools to reduce scarcity and demonstrates a method for modeling two-way (undirected) flows within a directed-network model using linear programming. Results indicate that exchange pools can help alleviate shortages from operational changes (reduced imported water) in Los Angeles, but providing more parties with access to storage improves their effectiveness. Exchange pools could potentially provide 6–12% of total supplies and reduce shortages as much as 86%. Considerations for organizing exchange pools are discussed to explore policy implications for managing common pool resources. The analytical method for embedding undirected network flows within a larger directed-network model has wide applicability for water resource systems analysis applications, including modeling water markets and interbasin transfers. * U.C. Davis hosts a discussion of the content by the authors at California Water Blog. 

Groundwater Flow Model of the East and South Las Posas Sub-Basins – Preliminary Draft Report

Calleguas Municipal Water District (CMWD) | January 17th, 2018

INTERA Incorporated (INTERA) was retained by the Calleguas Municipal Water District (CMWD) to develop a numerical groundwater model of the East Las Posas Management Area

INTERA Incorporated (INTERA) was retained by the Calleguas Municipal Water District (CMWD) to develop a numerical groundwater model of the East Las Posas Management Area (ELPMA), which includes the locally-recognized east and south sub-basins of the Las Posas Valley Basin (LPVB). Groundwater in the ELPMA is found in a multiple-aquifer system characterized by intense faulting and folding, which is known to exert structural controls on groundwater flow and movement. The ELPMA is known to receive recharge from surface water flows in Arroyo Las Posas/Simi that runs east to west along the southern edge of the basin. Flows in the Arroyo have become perennial as a result of discharges from wastewater treatment plants and dewatering wells within and upstream of the ELPMA. Hence, understanding and modeling the surface-water/groundwater interaction along the Arroyo is an important component of the numerical model development. CMWD also owns and operates the Las Posas Basin Aquifer Storage and Recovery (ASR) Project, consisting of eighteen high capacity ASR wells and associated facilities located in the ELPMA that are used to inject and recover potable water purchased from Metropolitan Water District of Southern California (Metropolitan). Basin response to injection/extractions at the ASR well fields and the evaluation of storage capacity of the ASR well field are key considerations for this modeling project. 

Groundwater Geology and Hydrology of Death Valley National Park, California and Nevada

U.S. Department of the Interior (DOI) | December 3rd, 2012

Groundwater Hydraulics

American Geophysical Union (AGU) | January 1st, 1984

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 9. John Ferris's research has covered a broad range of hydrologic p

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 9. John Ferris's research has covered a broad range of hydrologic problems in groundwater, including pollution, storage, recharge, and pumping of groundwater; drainage design; hydraulics of aquifer systems; saltwater encroachment; and application of geophysics to groundwater development. These contributions have been made as a researcher and teacher of national and international renown during a career that has lasted more than four decades. During these four decades, the methodologies for application of hydraulics to solving groundwater problems have continued to evolve and improve. The development of aquifer test techniques and analytical solutions been coemonplace in the 1950's, 1960's, and early 1970's have increasingly been supplemented by the use of numerical methods and automated parameter estimation techniques.

Groundwater Management: The Use of Numerical Models

American Geophysical Union (AGU) | February 1st, 1980

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 5. The first proposal for an assessment of groundwater models follo

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 5. The first proposal for an assessment of groundwater models followed the 1973 meeting of the Scientific Committee on Problems of the Environment (SCOPE), part of the International Council of Scientific Unions (ICSU), in Kiel, Federal Republic of Germany. SCOPE invited the Holcomb Research Institute (HRI) of Butler University, Indianapolis, Indiana to undertake the assessment since it had just completed a critical evaluation of the roles of mathematical models in environmental decision?]making in the United States (HRI, 1976). An international steering committee, chaired by John Bredehoeft of the U.S. Geological Survey, was assembled for the proposed study. Yehuda Bachmat was the on?]site head of the project, having come to the Institute on a year's leave from his position as Director of Research, Hydrological Service of Israel.

Groundwater microbiomes balance resilience and vulnerability to hydroclimatic extremes

Nature Portfolio (Springer Nature) | August 20th, 2025

Groundwater Modeling by the Finite Element Method

American Geophysical Union (AGU) | January 1st, 1989

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 13. The finite element method is now widely used to solve a variety

Published by the American Geophysical Union as part of the Water Resources Monograph Series, Volume 13. The finite element method is now widely used to solve a variety of important problems in the field of groundwater hydrology. Thus a clear understanding of the method is essential to scientists and engineers working in this field. The goal of this book is to provide the reader with the basic skills needed to use the finite element method to solve "real-world" problems. Examples are used throughout the text to illustrate each step in the solution process.