An ongoing shift in Pacific Ocean sea level

American Geophysical Union (AGU) | July 30th, 2016

Based on the satellite altimeter data, sea level off the west coast of the United States has increased over the past 5 years, while sea level in the western tropical Pac

Based on the satellite altimeter data, sea level off the west coast of the United States has increased over the past 5 years, while sea level in the western tropical Pacific has declined. Understanding whether this is a short-term shift or the beginning of a longer-term change in sea level has important implications for coastal planning efforts in the coming decades. Here, we identify and quantify the recent shift in Pacific Ocean sea level, and also seek to describe the variability in a manner consistent with recent descriptions of El Nino-Southern Oscillation (ENSO) and particularly the Pacific Decadal Oscillation (PDO). More specifically, we extract two dominant modes of sea level variability, one related to the biennial oscillation associated with ENSO and the other representative of lower-frequency variability with a strong signal in the northern Pacific. We rely on cyclostationary empirical orthogonal function (CSEOF) analysis along with sea level reconstructions to describe these modes and provide historical context for the recent sea level changes observed in the Pacific. As a result, we find that a shift in sea level has occurred in the Pacific Ocean over the past few years that will likely persist in the coming years, leading to substantially higher sea level off the west coast of the United States and lower sea level in the western tropical Pacific.

An Update of the Death Valley Regional Groundwater Flow System Transient Model, Nevada and California

U.S. Geological Survey (USGS) | October 31st, 2016

The U.S. Geological Survey (USGS) has revised the regional-scale Death Valley regional groundwater flow system (DVRFS) numerical model with new data and interpretations s

The U.S. Geological Survey (USGS) has revised the regional-scale Death Valley regional groundwater flow system (DVRFS) numerical model with new data and interpretations since the original numerical flow model was published in 2004 (Belcher (2004); re-published as Belcher and Sweetkind [2010]). Since the original publication of the DVRFS flow model, additional data have been collected and interpretations have been made. Cooperators such as the Bureau of Land Management, National Park Service, U.S. Fish and Wildlife Service, the Department of Energy, and Nye County, Nevada, recognized a need to update the existing regional numerical flow model to maintain its viability as a groundwater management tool for regional stakeholders. For the purposes of this report, the version of the DVRFS numerical flow model documented in Belcher and Sweetkind (2010) and Faunt, Blainey, and others (2010) is designated as DVRFS v. 1.0. The updated version, as presented in this report, is referred to as DVRFS v. 2.0. Knowledge of basin water balances and the magnitude of interbasin groundwater flow is the basis for regional groundwater management and water-resource planning in the Great Basin of Nevada (Scott and others, 1971). Rapid population growth, arid conditions, and increased water use have led to development of available groundwater resources. Groundwater use in some alluvial-fill basins has resulted in continued water-level declines and land subsidence. Adjacent bedrock aquifers are increasingly being targeted for additional development. Such groundwater development may potentially impact local and regional water quantity and quality, existing water rights, and wildlife habitats. An understanding of hydrogeologic processes that control the rate and direction of groundwater flow in southern Nevada is necessary to assess the potential effects of any proposed large-scale groundwater development. Potential water-resource conflicts exist because of disparate interests in the region, particularly with respect to the development of groundwater resources to meet agricultural, municipal, and industrial water demand and the need to protect habitat for endangered and threatened species. Water demands in the Amargosa Farms area from agricultural and suburban development, and rapidly urbanizing areas in Las Vegas and Pahrump Valleys place increasing pressure on existing groundwater resources. In addition, several solar-energy facilities have been proposed within the Death Valley region; water demands for these facilities will vary. Natural groundwater discharge at springs and seeps sustains habitat for numerous species, many of which are threatened, endangered, or otherwise considered sensitive. In 2004, the USGS documented a calibrated numerical flow model of the DVRFS (Belcher, 2004). The model, DVRFS v. 1.0, incorporated elements of several precursor numerical models but defined the boundaries of the regional flow system slightly different than in previous versions. The model simulates transient groundwater flow conditions in the DVRFS from 1913 through 1998. The report was subsequently revised and published as a USGS Professional Paper (Belcher and Sweetkind, 2010). Since release of DVRFS v. 1.0 in 2004, continued use of the model by cooperators, stakeholders, and interested parties in the region has demonstrated the need to improve specific aspects (such as the flow into northern Yucca Flat and parts of the Amargosa Desert), to update it with more recently acquired geologic and hydrologic data, and to extend the simulation period.

Analysis of Groundwater Basin Yield, Upper Santa Clara River Groundwater Basin, East Subbasin, Los Angeles County, California

Castaic Lake Water Agency | August 15th, 2005

This report presents an evaluation of the long-term sustainability of existing groundwater management practices in the Santa Clarita Valley, located in northwestern Los

This report presents an evaluation of the long-term sustainability of existing groundwater management practices in the Santa Clarita Valley, located in northwestern Los Angeles County, California. The groundwater system in the Santa Clarita Valley is identified by the California Department of Water Resources (DWR) as the Santa Clara River Valley Groundwater Basin, East Subbasin (Basin No. 4-4.07) and lies within the DWR-designated Upper Santa Clara River Hydrologic Area. Groundwater in the basin is pumped from a shallow Alluvial Aquifer and deeper groundwater resources that are present in an older, underlying unit called the Saugus Formation. Most groundwater pumping is by the local water purveyors (the Upper Basin Water Purveyors [herein referred to as the Purveyors1]) for municipal uses (in the range of approximately 23,000 to 28,000 acre-feet per year [AF/yr] in recent years), with some continuing pumping by private landowners, primarily for irrigation uses (approximately 15,000 to 16,000 AF/yr in recent years). The Purveyors also have access to other sources of water, including imported State Water Project (SWP) water, groundwater banking outside the basin, recycled water, short-term water exchanges, and dry-year water purchase programs (Luhdorff & Scalmanini Consulting Engineers [LSCE], 2005a). The water management practices of the Purveyors call for maximizing the use of Alluvial Aquifer and imported water during years of normal or above-normal availability of these supplies, and limiting the use of the Saugus Formation during these periods, then temporarily increasing Saugus Formation pumping during years when supplemental imported water supplies are significantly reduced because of drought conditions. The evaluation of the Purveyors’ current groundwater management practices has been performed using a detailed numerical groundwater flow model of the basin. The model, called the Santa Clarita Valley Groundwater Model (Regional Model), simulates the occurrence and flow of groundwater, including its interaction with streams in the area. The Regional Model has been developed for the Purveyors as a tool for the analysis of groundwater management options in the context of future water demands and water supply conditions in the valley. Among the objectives in developing the model were (1) to be able to evaluate the long-term sustainability (yield) of the Alluvial and Saugus aquifer systems under a range of existing and potential future water resource management conditions, and (2) to facilitate general management of water quantity and water quality issues. Figure 1-1 is a map showing the area simulated by the model (tables and figures are located at the end of each section).  

Analysis of Potential Water-Supply Management Options, 2010-60, and Documentation of Revisions to the Model of the Irwin Basin Aquifer System, Fort Irwin National Training Center, California

U.S. Geological Survey (USGS) | October 31st, 2014

The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional

The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional, finite-difference groundwater-flow model—the U.S. Geological Survey’s MOD-FLOW—of the aquifer system in the basin was updated and the initial input dataset was supplemented with groundwater withdrawal data for the period 2000–10. The updated model was then used to simulate four combinations, or scenarios, of groundwater withdrawal and recharge over the next 50 years (January 2011 through December 2060). The scenarios included combinations of continuing withdrawals from currently active production wells, supplementing any increases in demand with withdrawals from an inactive production well, reducing withdrawal amounts and rates, and reducing the discharge of treated wastewater to infiltration ponds that provide a recharge source to the underlying aquifer. Results of the simulations indicated that, depending on the scenario implemented, groundwater levels would rise (over the next 50 years) from 40 feet to as much as 65 feet in the northwestern part of the Irwin Basin, and from 5 feet to 10 feet in the southeastern part.

Analysis of the Carmel Valley Alluvial Ground-Water Basin, Monterey County, California

U.S. Geological Survey (USGS) | June 14th, 1984

A two-dimensional, finite-element, digital model was developed for the Carmel Valley alluvial ground-water basin using measured, computed, and estimated discharge

A two-dimensional, finite-element, digital model was developed for the Carmel Valley alluvial ground-water basin using measured, computed, and estimated discharge and recharge data for the basin. Discharge data included evapotranspiration by phreatophytes and agricultural, municipal, and domestic pumpage. Recharge data included river leakage, tributary runoff, and pumping return flow. Recharge from subsurface boundary flow and rainfall infiltration was assumed to be insignificant. From 1974 through 1978, the annual pumping rate ranged from 5,900 to 9,100 acre-feet per year with 55 percent allotted to municipal use principally exported out of the valley, 44 percent to agricultural use, and 1 percent to domestic use. The pumpage return flow within the valley ranged from 900 to 1,500 acre-feet per year. The aquifer properties of transmissivity (about 5,900 feet squared per day) and of the storage coefficient (0.19) were estimated from an average alluvial thickness of 75 feet and from less well-defined data on specific capacity and grain-size distribution. During calibration the values estimated for hydraulic conductivity and storage coefficient for the lower valley were reduced because of the smaller grain size there. The river characteristics were based on field and laboratory analyses of hydraulic conductivity and on altitude survey data. The model is intended principally for simulation of flow conditions using monthly time steps. Time variations in transmissivity and short-term, high- recharge potential are included in the model. The years 1974 through 1978 (including "pre-" and "post-" drought) were selected because of the extreme fluctuation in water levels between the low levels measured during dry years and the above-normal water levels measured during the preceding and following wet years. Also, during this time more hydrologic information was available. Significantly, computed water levels were generally within a few feet of the measured levels, and computed flows were close to gaged river flows for this simulation. However, the nonuniqueness of solutions with respect to different sets of data indicates the model does not necessarily validate the correctness of the individual variables. The model might be improved with additional knowledge of the distribution of confining sediments in the lower end of the valley and the aquifer properties above and below them. The solution algorithm could account for confinement or partial confinement in the lower end of the valley plus contributions from the Tularcitos aquifer.

Analysis of the costs and benefits of using marsh restoration as a sea level rise adaptation strategy in San Francisco Bay

Bay Institute | February 22nd, 2013

The purpose of this study is to examine opportunities to protect San Francisco Bay’s recovering tidal marsh ecosystems while helping bayshore communities to manage the

The purpose of this study is to examine opportunities to protect San Francisco Bay’s recovering tidal marsh ecosystems while helping bayshore communities to manage the impacts of sea level rise. Specifically, it considers the flood risk management functions that tidal marshes perform naturally and evaluates the possibility of integrating those functions into a co-beneficial shoreline management strategy. The study’s intended audience is planners, politicians, regulators, and other stakeholders with the authority to make or affect decisions that influence the configuration and use of the San Francisco Bay shoreline. The study examines the current functions of San Francisco Bay tidal marshes as well as existing flood risk management strategies. It considers how environmental conditions are likely to change in the era of climate change, and how we can adapt our marshes and our flood risk management practices to accommodate these changes.

Anderson Subbasin Groundwater Sustainability Plan

Enterprise Anderson Groundwater Sustainability Agency | January 20th, 2022

This GSP covers all of the 98,700 acres of the Anderson Subbasin. The GSP describes the current groundwater conditions and hydrogeologic conceptual model, establishes a

This GSP covers all of the 98,700 acres of the Anderson Subbasin. The GSP describes the current groundwater conditions and hydrogeologic conceptual model, establishes a water budget, outlines local sustainable management criteria (SMC or SMCs), and describes projects and management actions for maintaining sustainability through the GSP planning and implementation period. Due to size, this file has been divided into 9 parts. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9

Annual Investigation and Report of Groundwater Conditions within United Water Conservation District

United Water Conservation District (UWCD) | March 8th, 2016

Annual Operating Plan for Colorado River Reservoirs 2021

U.S. Bureau of Reclamation (USBR) | December 9th, 2020

Antelope Valley Groundwater Cases

Superior Court of California, County of Los Angeles | December 23rd, 2015

The complaints and cross-complaints in the Action frame many legal issues. The Action includes over 4,000 Parties, as well as the members of the Non-Pumper Class and the

The complaints and cross-complaints in the Action frame many legal issues. The Action includes over 4,000 Parties, as well as the members of the Non-Pumper Class and the members of the Small Pumper Class. The Basin’s entire Groundwater supply and Groundwater rights, extending over approximately 1390 square miles, have been brought to issue. The numerous Groundwater rights at issue in the case include, without limitation, overlying, appropriative, prescriptive, and federal reserved water rights to Groundwater, rights to return flows from Imported Water, rights to recycled water, rights to stored Imported Water subject to the Watermaster rules and regulations, and rights to utilize the storage space within the Basin. After several months of trial, the Court made findings regarding Basin characteristics and determined the Basin’s Safe Yield. The Court’s rulings and judgments in this case, including the Safe Yield determination, form the basis for this Judgment. For annual reports go to the Department of Water Resources Adjudicated Annual Reporting page.