Death Valley regional ground-water flow system, Nevada and California—Hydrogeologic framework and transient ground-water flow model

U.S. Geological Survey (USGS) | July 1st, 2010

A numerical three-dimensional (3D) transient groundwater flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Ener

A numerical three-dimensional (3D) transient groundwater flow model of the Death Valley region was developed by the U.S. Geological Survey for the U.S. Department of Energy programs at the Nevada Test Site and at Yucca Mountain, Nevada. Decades of study of aspects of the groundwater flow system and previous less extensive groundwater flow models were incorporated and reevaluated together with new data to provide greater detail for the complex, digital model. A 3D digital hydrogeologic framework model (HFM) was developed from digital elevation models, geologic maps, borehole information, geologic and hydrogeologic cross sections, and other 3D models to represent the geometry of the hydrogeologic units (HGUs). Structural features, such as faults and fractures, that affect groundwater flow also were added. The HFM represents Precambrian and Paleozoic crystalline and sedimentary rocks, Mesozoic sedimentary rocks, Mesozoic to Cenozoic intrusive rocks, Cenozoic volcanic tuffs and lavas, and late Cenozoic sedimentary deposits of the Death Valley regional groundwater flow system (DVRFS) region in 27 HGUs. Information from a series of investigations was compiled to conceptualize and quantify hydrologic components of the groundwater flow system within the DVRFS model domain and to provide hydraulic-property and head-observation data used in the calibration of the transient-flow model. These studies reevaluated natural groundwater discharge occurring through evapotranspiration (ET) and spring flow; the history of groundwater pumping from 1913 through 1998; groundwater recharge simulated as net infiltration; model boundary inflows and outflows based on regional hydraulic gradients and water budgets of surrounding areas; hydraulic conductivity and its relation to depth; and water levels appropriate for regional simulation of prepumped and pumped conditions within the DVRFS model domain. Simulation results appropriate for the regional extent and scale of the model were provided by acquiring additional data, by reevaluating existing data using current technology and concepts, and by refining earlier interpretations to reflect the current understanding of the regional groundwater flow system. Groundwater flow in the Death Valley region is composed of several interconnected, complex groundwater flow systems. Groundwater flow occurs in three subregions in relatively shallow and localized flow paths that are superimposed on deeper, regional flow paths. Regional groundwater flow is predominantly through a thick Paleozoic carbonate rock sequence affected by complex geologic structures from regional faulting and fracturing that can enhance or impede flow. Spring flow and ET are the dominant natural groundwater discharge processes. Groundwater also is withdrawn for agricultural, commercial, and domestic uses. Groundwater flow in the DVRFS was simulated using MODFLOW-2000, the U.S. Geological Survey 3D finitedifference modular groundwater flow modeling code that incorporates a nonlinear least-squares regression technique to estimate aquifer parameters. The DVRFS model has 16 layers of defined thickness, a finite-difference grid consisting of 194 rows and 160 columns, and uniform cells 1,500 meters (m) on each side. Prepumping conditions (before 1913) were used as the initial conditions for the transient-state calibration. The model uses annual stress periods with discrete recharge and discharge components. Recharge occurs mostly from infiltration of precipitation and runoff on high mountain ranges and from a small amount of underflow from adjacent basins. Discharge occurs primarily through ET and spring discharge (both simulated as drains) and water withdrawal by pumping and, to a lesser amount, by underflow to adjacent basins simulated by constant-head boundaries. All parameter values estimated by the regression are reasonable and within the range of expected values. The simulated hydraulic heads of the final calibrated transient model generally fit observed heads reasonably well (residuals with absolute values less than 10 meters) with two exceptions: in most areas of nearly flat hydraulic gradient the fit is considered moderate (residuals with absolute values of 10 to 20 meters), and in areas of steep hydraulic gradient along the Eleana Range and western part of Yucca Flat, southern part of the Owlshead Mountains, southern part of the Bullfrog Hills, and the north-northwestern part of the model domain (residuals with absolute values greater than 20 meters). Groundwater discharge residuals are fairly random, with as many areas where simulated flows are less than observed flows as areas where simulated flows are greater. The highest unweighted groundwater discharge residuals occur at Death Valley, Sarcobatus Flat (northeastern area), Tecopa, and early observations at Manse Spring in Pahrump Valley. High weighted-discharge residuals were computed in Indian Springs Valley and parts of Death Valley. Most of these inaccuracies in head and discharge can be attributed to insufficient representation of the hydrogeology in the HFM and(or) discharge estimates, misrepresentation of water levels, and(or) model error associated with grid-cell size. The model represents the large and complex groundwater flow system of the Death Valley region at a greater degree of refinement and accuracy than has been possible previously. The representation of detail provided by the 3D digital hydrogeologic framework model and the numerical groundwater flow model enabled greater spatial accuracy in every model parameter. The lithostratigraphy and structural effects of the hydrogeologic framework; recharge estimates from simulated net infiltration; discharge estimates from ET, spring flow, and pumping; and boundary inflow and outflow estimates all were reevaluated, some additional data were collected, and accuracy was improved. Uncertainty in the results of the flow model simulations can be reduced by improving on the quality, interpretation, and representation of the water-level and discharge observations used to calibrate the model and improving on the representation of the HGU geometries, the spatial variability of HGU material properties, the flow model physical framework, and the hydrologic conditions.

Declines in Peak Snow Water Equivalent and Elevated Snowmelt Rates Following the 2020 Cameron Peak Wildfire in Northern Colorado

American Geophysical Union (AGU) | March 28th, 2023

The loss of tree canopy greatly increases the amount of solar energy that reaches the snow surface. Soot and debris from burned trees make the snow surface darker, result

The loss of tree canopy greatly increases the amount of solar energy that reaches the snow surface. Soot and debris from burned trees make the snow surface darker, resulting in more of this energy being absorbed. Late-season snow storms were able to temporarily counteract some of these effects by burying the darker snow surface. As more and more of the western United States is fire-impacted, it is essential to better understand and account for these impacts on this critical water reservoir for this region.

Declining Reservoir Reliability and Increasing Reservoir Vulnerability: Long‐Term Observations Reveal Longer and More Severe Periods of Low Reservoir Storage for Major United States Reservoirs

American Geophysical Union (AGU) | August 22nd, 2024

Deepening water scarcity in breadbasket nations

Nature Portfolio (Springer Nature) | January 28th, 2025

Water is crucial for meeting sustainability targets, but its unsustainable use threatens human wellbeing and the environment. Past assessments of water scarcity (i.e., wa

Water is crucial for meeting sustainability targets, but its unsustainable use threatens human wellbeing and the environment. Past assessments of water scarcity (i.e., water demand in exceedance of availability) have often been spatially coarse and temporally limited, reducing their utility for targeting interventions. Here we perform a detailed monthly sub-basin assessment of the evolution of blue (i.e., surface and ground) water scarcity (years 1980-2015) for the world’s three most populous countries – China, India, and the USA. Disaggregating by specific crops and sectors, we find that blue water demand rose by 60% (China), 71% (India), and 27% (USA), dominated by irrigation for a few key crops (alfalfa, maize, rice, wheat). We also find that unsustainable demand during peak months of use has increased by 101% (China), 82% (India), and 49% (USA) and that 32% (China), 61% (India), and 27% (US) of sub-basins experience at least 4 months of scarcity. These findings demonstrate that rising water demands are disproportionately being met by water resources in already stressed regions and provide a basis for targeting potential solutions that better balance the water needs of humanity and nature.

Defining Snow Drought and Why It Matters

American Geophysical Union (AGU) | February 28th, 2017

On 12 February, water resource managers at the Oroville Dam issued an evacuation warning that forced some 180,000 Californians to relocate to higher ground. The story of

On 12 February, water resource managers at the Oroville Dam issued an evacuation warning that forced some 180,000 Californians to relocate to higher ground. The story of how conditions got to this point involves several factors, but two clearly stand out: the need to prevent water shortages during a record drought, followed by one of the wettest October–February periods in California history.

Delta Adapts: Creating a Climate Resilient Future

Delta Stewardship Council (Delta Council) | June 25th, 2021

The time to act is now. Climate change is already altering the physical environment of the Sacramento–San Joaquin Delta and Suisun Marsh (Delta), and we will continue t

The time to act is now. Climate change is already altering the physical environment of the Sacramento–San Joaquin Delta and Suisun Marsh (Delta), and we will continue to experience its effects through hotter temperatures, more severe wildfires, and prolonged droughts. Over the long term, climate change in the Delta is expected to harm human health and safety, disrupt the economy, diminish water supply availability and usability, shift ecosystem function, compromise sensitive habitats, and increase the challenges of providing basic services. Many of these impacts will disproportionately affect vulnerable communities. Although the exact extent and timing of these impacts is uncertain, this climate change vulnerability assessment phase of Delta Adapts will help the Delta Stewardship Council (Council) understand specific regional climate risks and vulnerabilities. Regional, collaborative adaptation strategies rooted in science are more critical than ever. The next phase of Delta Adapts, preparing an adaptation strategy, will identify ways to address the risks and vulnerabilities.

Delta Conveyance Project: Modernizing California’s Water Infrastructure, Fast Facts 2024

California Department of Water Resources (DWR) | September 13th, 2023

Depletion and response of deep groundwater to climate-induced pumping variability

Nature Portfolio (Springer Nature) | January 23rd, 2017

Groundwater constitutes a critical component of our water resources. Widespread groundwater level declines have occurred in the USA over recent decades, including

Groundwater constitutes a critical component of our water resources. Widespread groundwater level declines have occurred in the USA over recent decades, including in regions not typically considered water stressed, such as areas of the Northwest and mid-Atlantic Coast. This loss of water storage reflects extraction rates that exceed natural recharge and capture. Here, we explore recent changes in the groundwater levels of deep aquifers from wells across the USA, and their relation to indices of interannual to decadal climate variability and to annual precipitation. We show that groundwater level changes correspond to selected global climate variations. Although climate-induced variations of deep aquifer natural recharge are expected to have multi-year time lags, we find that deep groundwater levels respond to climate over timescales of less than one year. In irrigated areas, the annual response to local precipitation in the deepest wells may reflect climate-induced pumping variability. An understanding of how the human response to drought through pumping leads to deep groundwater changes is critical to manage the impacts of interannual to decadal and longer climate variability on the nation’s water resources.

Desalination - Brackish and Sea Water (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

Desalination, the removal of salts from saline waters, is one of the few options available to augment California’s water supply. California has facilities that desalina

Desalination, the removal of salts from saline waters, is one of the few options available to augment California’s water supply. California has facilities that desalinate sea water for coastal communities and brackish groundwater for inland water users — many of which have provided high-quality water to their customers for more than 10 years. As water supplies in California become more constrained, many water suppliers with nearby saline water sources are evaluating desalination as a way to provide reliable supply in response to uncertainties relating to future drought and climate change. While desalination is not a viable method for many water suppliers in the state, some not yet engaged in the process could realize significant supply and reliability benefits — even though desalination of both sea water and brackish groundwater comes with financial and environmental challenges. For water suppliers with desalination opportunities, how they implement environmentally sustainable projects is a key issue facing multiple California communities.

Desalination and sustainability - An appraisal and current perspective

Water Research, Elsevier | February 1st, 2016

Desalination technologies have evolved and advanced rapidly along with increasing water demands around the world since 1950s. Many reviews have focused on the techno-econ

Desalination technologies have evolved and advanced rapidly along with increasing water demands around the world since 1950s. Many reviews have focused on the techno-economic and environmental and ecological issues of the desalination technologies and emphasized the feasibility of desalination industry as an alternative to meet the water demands in many water scarce regions. Despite these efforts, many perceptions about desalination processes hinder their applications for potential water supplies. This article has two specific aims: 1) provide an overview of the desalination trends around the world and discuss the sustainability components of desalination processes in comparison with other water supply alternatives; and 2) discuss case studies for desalination, and drivers and factors that influence sustainable desalination and other alternative water sources for desalination to increase our current understanding on the sensitive and futuristic issues of water supply and resource management options for drought facing regions. Although some of the facts and recent developments discussed here show that desalination can be affordable and potentially sustainable, contributions that meaningfully address socio-economic and ecological and environmental issues of desalination processes are urgently required in this critical era of severe water stress for the present context and the future development of desalination technologies.