South Lahontan

Estimated Ground-Water Withdrawals from the Death Valley Regional Flow System

U.S. Geological Survey (USGS) | July 1st, 2003

Evaluation of Geohydrologic Framework, Recharge Estimates, and Ground-Water Flow of the Joshua Tree Area, San Bernardino County, California

U.S. Geological Survey (USGS) | February 7th, 2005

Ground water historically has been the sole source of water supply for the community of Joshua Tree in the Joshua Tree ground-water subbasin of the Morongo ground-water b

Ground water historically has been the sole source of water supply for the community of Joshua Tree in the Joshua Tree ground-water subbasin of the Morongo ground-water basin in the southern Mojave Desert. The Joshua Basin Water District (JBWD) supplies water to the community from the underlying Joshua Tree ground-water subbasin. The JBWD is concerned with the long-term sustainability of the underlying aquifer. To help meet future demands, the JBWD plans to construct production wells in the adjacent Copper Mountain ground-water subbasin. As growth continues in the desert, there may be a need to import water to supplement the available ground-water resources. In order to manage the ground-water resources and to identify future mitigating measures, a thorough understanding of the ground-water system is needed. The purpose of this study was threefold: (1) improve the understanding of the geohydrologic framework of the Joshua Tree and Copper Mountain ground-water subbasins, (2) determine the distribution and quantity of recharge using field and numerical techniques, and (3) develop a ground-water flow model that can be used to help manage the water resources of the region.

Evaluation of Land Subsidence and Ground Failures at Bicycle Basin, Fort Irwin National Training Center, California, 1992–2017

U.S. Geological Survey (USGS) | June 5th, 2019

Groundwater has been pumped in the Bicycle Basin at Fort Irwin National Training Center since the 1960s, and the amount pumped has generally increased since the 1990s. Af

Groundwater has been pumped in the Bicycle Basin at Fort Irwin National Training Center since the 1960s, and the amount pumped has generally increased since the 1990s. After a large crack (approximately 0.5-kilometer long) formed at the surface of Bicycle Lake playa during 2005–06 in the area used as an aircraft runway, a monitoring study was initiated by the U.S. Geological Survey, in cooperation with the U.S. Army Fort Irwin National Training Center, to help determine the cause. The extent and effect of groundwater-level declines and land-surface deformation in Bicycle Basin were evaluated using a number of approaches, including water-level measurements from December 2007 to June 2017, land surveys across the playa area, interferometric synthetic aperture radar (InSAR) analyses, geophysical surveys of the playa area, and numerical experiments to test hypotheses about soil mechanical processes. A specific objective of this study was to evaluate the recent development of ground failures in the form of large, surface cracks that pose a hazard to aircraft operations on the Bicycle Lake playa airstrip.  Another large crack and set of interconnected cracks formed at the surface of Bicycle Lake playa in 2013 following a period of inundation similar to that of 2005–06; however, the 2013 cracks formed a network rather than a single feature. Groundwater pumping resulted in more than 27 meters (90 feet) of water-level declines in wells north of the Bicycle Lake playa from 1990 to 2017, and InSAR interferograms indicated more than 400 millimeters (16 inches) of subsidence during 1993–2015. Subsidence rates calculated from InSAR interferograms were variable, temporally and spatially. Results of leveling surveys indicated differential subsidence between 2009 and 2016 along a transect across the playa to the area of maximum subsidence; there was less subsidence south of the 2005–06 crack than north of it. The steepest subsidence gradient for this time was in the area of maximum subsidence. Repeat tape-extensometer measurements from April 2009 to November 2017 across the main-runway crack indicated slight opening along part of the crack. A baseline lidar (light detection and ranging) survey of the main-runway crack was done in January 2009 to track the development of this feature. During the 95-months from January 2009 to December 2016, 0.5 meters (19.7 inches) of subsidence was observed next to the subsidence pit in the crack along the western end of the scanned area, presumably due to erosion and backfilling when the lake was inundated. Standing water in the crack along the eastern end of the scanned area prevented determining change for that part of the crack. Time-series, shaded-relief images show the progression of change in the crack from January 2009 through December 2016, with the crack closing and opening, depending on the time of most recent inundation relative to when the scans were taken. Volumetric changes in the size of the crack, calculated between the sequential lidar surveys, show that from 2009 to 2016, the cumulative volumetric change was 1.5 cubic meters (54 cubic feet). This volume is a minimum estimate because the crack volume below the water surface in the pits was not included in the calculations. Subsurface imaging of the 2005–06 main-runway crack by a series of electrical resistivity tomography surveys in 2008 and 2017 indicated that the crack could extend 5 meters (16 feet) in the subsurface.  Electromagnetic induction surveys in 2008, 2014, and 2015 evaluated the technique for ground-failure monitoring and showed that the technique was effective at revealing anomalies correlated with the features of concern in the playa area, such as the 2005–06 crack, numerous ”healed” macropolygon features, and scattered sink-like depressions.  Results from numerical experiments simulating water-table decline at depth indicated that the material deposits in the desaturating capillary fringe zone might not be able to transmit large enough stresses up through the overlying soil to cause cracks at the land surface. Results from simulations of desiccation in the presence of a regional tectonically induced stress field, however, tended to support the hypothesis that the combined processes could control the formation of giant desiccation macropolygons in certain areas, such as Bicycle Lake playa.

Evaluation of the characteristics, discharge, and water quality of selected springs at Fort Irwin National Training Center, San Bernardino County, California

U.S. Geological Survey (USGS) | March 29th, 2024

Eight springs and seeps at Fort Irwin National Training Center were described and categorized by their general characteristics, discharge, geophysical properties, and wat

Eight springs and seeps at Fort Irwin National Training Center were described and categorized by their general characteristics, discharge, geophysical properties, and water quality between 2015 and 2017. The data collected establish a modern (2017) baseline of hydrologic conditions at the springs. Two types of springs were identified: (1) precipitation-fed upland springs (Cave, Desert King, Devouge, No Name, and Panther Springs) and (2) groundwater discharge-fed basin springs (Garlic, Bitter, and Jack Springs). Comparison of electrical resistivity tomography data collected at groundwater basin springs from 2015 to 2017 indicated that spring discharge and connection to the underlying groundwater system is highly focused, although the springs themselves appear diffuse and are spread out over a large area.

Evaluation of the Hydrologic System and Selected Water-Management Alternatives in the Owens Valley, California

U.S. Geological Survey (USGS) | May 9th, 2000

The Owens Valley, a long, narrow valley along the east side of the Sierra Nevada in east-central California, is the main source of water for the city of Los Angeles. The

The Owens Valley, a long, narrow valley along the east side of the Sierra Nevada in east-central California, is the main source of water for the city of Los Angeles. The city diverts most of the surface water in the valley into the Owens River–Los Angeles Aqueduct system, which transports the water more than 200 miles south to areas of distribution and use. Additionally, ground water is pumped or flows from wells to supplement the surface-water diversions to the river–aqueduct system. Pumpage from wells needed to supplement water export has increased since 1970, when a second aqueduct was put into service, and local residents have expressed concerns that the increased pumping may have a detrimental effect on the environment and the native vegetation (indigenous alkaline scrub and meadow plant communities) in the valley. Native vegetation on the valley floor depends on soil moisture derived from precipitation and from the unconfined part of a multilayered ground-water system. This report, which describes the evaluation of the hydrologic system and selected water-management alternatives, is one in a series designed to identify the effects that ground-water pumping has on native vegetation and evaluate alternative strategies to mitigate any adverse effects caused by pumping. The hydrologic system of the Owens Valley can be conceptualized as having three parts: (1) an unsaturated zone affected by precipitation andevapotranspiration; (2) a surface-water system composed of the Owens River, the Los Angeles Aqueduct, tributary streams, canals, ditches, and ponds; and (3) a saturated ground-water system contained in the valley fill. Analysis of the hydrologic system was aided by development of a ground-water flow model of the “aquifer system,” which is defined as the most active part of the ground-water system and which includes nearly all of the Owens Valley except for the area surrounding the Owens Lake. The model was calibrated and verified for water years 1963–88 and used to evaluate general concepts of the hydrologic system and the effects of past water-management practices. The model also was used to evaluate the likely effects of selected water-management alternatives designed to lessen the adverse effects of ground-water pumping on native vegetation. Results of the model simulations confirm that a major change in the hydrologic system was caused by the additional export of water from the valley beginning in 1970. Average ground-water pumpage increased by a factor of five, discharge from springs decreased almost to zero, reaches of the Owens River that previously had gained water from the aquifer system began losing water, and total evapotranspiration by native plants decreased by about 35 percent. Water-management practices as of 1988 were defined and evaluated using the model. Simulation results indicate that increased ground-water pumpage since 1985 for enhancement and mitigation projects within the Owens Valley has further stressed the aquifer system and resulted in declines of the water table and reduced evapotranspiration. Most of the water-table declines are beneath the western alluvial fans and in the immediate vicinity of production wells. The water-table altitude beneath the valley floor has remained relatively constant over time because of hydrologic buffers, such as evapotranspiration, springs, and permanent surface-water features. These buffers adjust the quantity of water exchanged with the aquifer system and effectively minimize variations in water-table altitude. The widespread presence of hydrologic buffers is the primary reason the water-table altitude beneath the valley floor has remained relatively constant since 1970 despite major changes in the type and location of ground-water discharge. Evaluation of selected water-management alternatives indicates that long-term variations in average runoff to the Owens Valley of as much as 10 percent will not have a significant effect on the water-table altitude. However, reductions in pumpage to an average annual value of about 75,000 acre-ft/yr are needed to maintain the water table at the same altitude as observed during water year 1984. A 9-year transient simulation of dry, average, and wet conditions indicates that the aquifer system takes several years to recover from increased pumping during a drought, even when followed by average and above-average runoff and recharge. Increasing recharge from selected tributary streams by additional diversion of high flows onto the alluvial fans, increasing artificial recharge near well fields, and allocating more pumpage to the Bishop area may be useful in mitigating the adverse effects on native vegetation caused by drought and short-term increases in pumpage. Analysis of the optimal use of the existing well fields to minimize drawdown of the water table indicates no significant lessening of adverse effects on native vegetation at any of the well fields at the end of a 1-year simulation. Some improvement might result from pumping from a few high-capacity wells in a small area, such as the Thibaut–Sawmill well field; pumping from the upper elevations of alluvial fans, such as the Bishop well field; or pumping in an area surrounded by irrigated lands, such as the Big Pine well field. Use of these water-management techniques would provide some flexibility in management from one year to another, but would not solve the basic problem that increased ground-water pumpage causes decreases in evapotranspiration and in the biomass of native vegetation. Furthermore, the highly transmissive and narrow aquifer system will transmit the effects of pumping to other more sensitive areas of the valley within a couple of years. Other possible changes in water management that might be useful in minimizing the short-term effects of pumping on native vegetation include sealing well perforations in the unconfined part of the aquifer system; rotating pumpage among well fields; continuing or renewing use of unlined surface-water features such as canals and ditches; developing recharge and extraction facilities in deeper volcanic deposits near Big Pine or in alluvial fan deposits along the east side of the valley; installing additional wells along the west side of the Owens Lake; and conjunctively using other ground-water basins between the Owens Valley and Los Angeles to store exported water for subsequent extraction and use during droughts.

Evaluation of the Subseasonal Forecast Skill of Floods Associated with Atmospheric Rivers in Coastal Western U.S. Watersheds

American Meteorological Society (AMS) | May 27th, 2021

Atmospheric rivers (ARs) are responsible for up to 90% of major flood events along the U.S. West Coast. The time scale of subseasonal forecasting (from 2 weeks to 1 month

Atmospheric rivers (ARs) are responsible for up to 90% of major flood events along the U.S. West Coast. The time scale of subseasonal forecasting (from 2 weeks to 1 month) is a critical lead time for proactive mitigation of flood disasters. The NOAA Climate Testbed Subseasonal Experiment (SubX) is a research-to-operations project with almost immediate availability of forecasts. It has produced a reforecast database that facilitates evaluation of flood forecasts at these subseasonal lead times. Here, we examine the SubX-driven forecast skill of AR-related flooding out to 4-week lead using the Distributed Hydrology Soil Vegetation Model (DHSVM), with particular attention to the role of antecedent soil moisture (ASM), which modulates the relationship between meteorological and hydrological forecast skill. We study three watersheds along a transect of the U.S. West Coast: the Chehalis River basin in Washington, the Russian River basin in Northern California, and the Santa Margarita River basin in Southern California. We find that the SubX-driven flood forecast skill drops quickly after week 1, during which there is relatively high deterministic forecast skill. We find some probabilistic forecast skill relative to climatology as well as ensemble streamflow prediction (ESP) in week 2, but minimal skill in weeks 3–4, especially for annual maximum floods, notwithstanding some probabilistic skill for smaller floods in week 3. Using ESP and reverse-ESP experiments to consider the relative influence of ASM and SubX reforecast skill, we find that ASM dominates probabilistic forecast skill only for small flood events at week 1, while SubX reforecast skill dominates for large flood events at all lead times.

Evapotranspiration frequently increases during droughts

Nature Portfolio (Springer Nature) | October 27th, 2022

Changes in evapotranspiration (ET) affect water availability and ecosystem health. Higher evaporative demand during drought acts to increase ET, but droughts also reduce

Changes in evapotranspiration (ET) affect water availability and ecosystem health. Higher evaporative demand during drought acts to increase ET, but droughts also reduce the moisture supply necessary for ET, limiting predictions of even the sign of ET anomalies. Drought-driven increases in ET (ET+drought) are of particular concern because they quickly deplete water resources, causing flash droughts and acute stress on ecosystems. Here, using a water balance approach, we show that ET+drought is globally widespread, occurring in 44.4% of drought months. The sign of ET’s drought response depends most on the magnitude of precipitation and total water storage anomalies, rather than its location. The Coupled Model Intercomparison Project Phase 6 Earth system models underestimate the ET+drought probability by nearly one-half, and more so in drier regions, primarily due to missing representations of soil structure effects on soil evaporation, as well as incorrectly parameterized plant and soil traits. These processes should be prioritized to reduce model uncertainties in the water–energy–food nexus.

Evapotranspiration Water Use Analysis of Saltcedar and Other Vegetation in the Mojave River Floodplain, 2007 and 2010

U.S. Bureau of Reclamation (USBR) | August 15th, 2011

The Mojave Water Agency Water Supply Management Study, Phase 1 Report (Study) was developed to provide technical information on vegetation water usage in the Mojave River

The Mojave Water Agency Water Supply Management Study, Phase 1 Report (Study) was developed to provide technical information on vegetation water usage in the Mojave River floodplain, with emphasis on saltcedar. Study analyses included 2007 and 2010 classification of native and non-native vegetation, vegetation evapotranspiration (ET) modeling1, lidar elevation map development, groundwater mapping, and water evapotranspiration cost calculations. Results are presented as a whole and by Mojave Water Agency (MWA) subarea boundaries: Alto, Alto Transition, Centro, and Baja.

Examining the Contribution of the Observed Global Warming Trend to the California Droughts of 2012/13 and 2013/14

American Meteorological Society (AMS) | September 30th, 2014

In this study, we examine the November–February California droughts of 2012/13 and 2013/14. During 2013/14, California had its warmest and third driest rainy se

In this study, we examine the November–February California droughts of 2012/13 and 2013/14. During 2013/14, California had its warmest and third driest rainy season on record (1895–2014), while the 2012/13 season registered as the 45th warmest and 38th driest (Vose et al. 2014). The 2013 January–December calendar year was the driest on record (Water CA 2014). These consecutive below-normal seasons conspired with warm temperatures to reduce California’s snowpack to the second lowest level since 1960, when recording began, with snowpack at 24% of normal (Water CA 2014). Between January 2013 and January 2014, satellite observations documented dramatic snowpack-related land cover change (NASA Earth Observatory 2014): in 2014, the Cascade, Sierra Nevada, and Coastal ranges were almost completely devoid of snow. In February and March of 2014, air temperatures were extremely warm (NOAA NCDC 2014; HPRC 2014), and U.S. Geological Survey (USGS) observations indicated extreme or moderate hydrologic drought (USGS 2014) and high levels of vegetation stress (VegDRI 2014). The state declared a drought emergency (NIDIS 2014). While it is too soon to assess the full impact of the 2012/13 and 2013/14 California droughts, they seem likely to substantially impact the state’s ability to generate hydrologic power, support agriculture, reduce the risk of forest and bush fires, and protect fragile ecosystems (Huffington Post 2014). *Chapter 4, Explaining Extreme Events of 2013 from a Climate Perspective, Bull. Amer. Meteor. Soc., 95 (9)

Executive Order N-10-19

State of California | April 29th, 2019