Sustained Groundwater Loss in California's Central Valley Exacerbated by Intense Drought Periods.
Ontology highlight
ABSTRACT:
SUBMITTER: Ojha C
PROVIDER: S-EPMC6120459 | biostudies-literature | 2018 Jul
REPOSITORIES: biostudies-literature
Publications
Sustained Groundwater Loss in California's Central Valley Exacerbated by Intense Drought Periods.
Ojha Chandrakanta C Shirzaei Manoochehr M Werth Susanna S Argus Donald F DF Farr Tom G TG
Water resources research 20180704 7
The accelerated rate of decline in groundwater levels across California's Central Valley results from overdrafting and low rates of natural recharge and is exacerbated by droughts. The lack of observations with an adequate spatiotemporal resolution to constrain the evolution of groundwater resources poses severe challenges to water management efforts. Here we present SAR interferometric measurements of high-resolution vertical land motion across the valley, revealing multiscale patterns of aquif ...[more]
Similar Datasets
Project description:Range change data, obtained from Synthetic Aperture Radar satellites, form the basis for estimates of aquifer volume change in California's Central Valley. The estimation algorithm incorporates a function penalizing changes far from known well locations, linking the aquifer volume changes to agricultural, industrial, and municipal pumping within the Tulare basin. We show that the range changes are compatible with the hypothesis that the source of aquifer volume changes are variations in effective pressure around documented wells. Specifically, inclusion of the well distance penalty does not degrade the fit to the observations, inversions with and without it both give variance reductions of 99.6%. The patterns of aquifer volume change vary significantly from the drought year, between October 2015 and October 2016, to a wet year in 2017, and into 2018, a year with near average rainfall. The 2.3 million acre-feet of estimated volume reduction, a lower bound on the amount of water extracted from the basin between October 2015 and 2016, agrees with independent estimates of 1.8 and 2.3 million acre-feet. The aquifer volume reduction is also compatible with a loss of 3.1 km3 (2.5 million acre-feet) in groundwater volume derived from Gravity Recovery and Climate Experiment (GRACE) satellite data.
| S-EPMC6831828 | biostudies-literature
Project description:Across the world, declining groundwater levels cause wells to run dry, increase water and food insecurity, and often acutely impact groundwater-dependent communities. Despite the ubiquity and severity of these impacts, groundwater research has primarily focused on economic policy instruments for sustainable management or the quantification of groundwater depletion, rather than assessing the impacts of management decisions. In particular, how definitions of groundwater sustainability shape the fate of resource users remains unexplored. Here, we examine one of the world's largest-scale environmental sustainability reforms, the California Sustainable Groundwater Management Act (SGMA), and estimate the impact of sustainability definitions proposed in groundwater sustainability plans (GSPs) on well failure. We show that locally-proposed sustainability criteria are consistent with business as usual groundwater level decline, and if reached, could impact over 9000 domestic wells and around 1000 public supply wells. These findings highlight the necessity of careful and critical evaluation of locally-developed sustainability definitions and their implementation to prevent detrimental impacts, such as threats to household and municipal water supply.
| S-EPMC10491797 | biostudies-literature
Project description:BackgroundBetween 2013 and 2015, a large part of the western United States, including the Central Valley of California, sustained an extreme drought. The Central Valley is recognized as a region of hemispheric importance for waterbirds, which use flooded agriculture and wetlands as habitat. Thus, the impact of drought on the distribution of surface water needed to be assessed to understand the effects on waterbird habitat availability.MethodsWe used remote sensing data to quantify the impact of the recent extreme drought on the timing and extent of waterbird habitat during the non-breeding season (July-May) by examining open water in agriculture (rice, corn, and other crops) and managed wetlands across the Central Valley. We assessed the influence of habitat incentive programs, particularly The Nature Conservancy's BirdReturns and The Natural Resources Conservation Service's Waterbird Habitat Enhancement Program (WHEP), at offsetting habitat loss related to drought.ResultsOverall, we found statistically significant declines in open water in post-harvest agriculture (45-80% declines) and in managed wetlands (39-60% declines) during the 2013-2015 drought compared to non-drought years during the period of 2000-2011. Crops associated with the San Joaquin Basin, specifically corn, as well as wetlands in that part of the Central Valley exhibited larger reductions in open water than rice and wetlands in the Sacramento Valley. Semi-permanent wetlands on protected lands had significantly lower (39-49%) open water in the drought years than those on non-protected lands while seasonal wetlands on protected lands had higher amounts of open water. A large fraction of the daily open water in rice during certain times of the year, particularly in the fall for BirdReturns (61%) and the winter for WHEP (100%), may have been provided through incentive programs which underscores the contribution of these programs. However, further assessment is needed to know how much the incentive programs directly offset the impact of drought in post-harvest rice by influencing water management or simply supplemented funding for activities that might have been done regardless.DiscussionOur landscape analysis documents the significant impacts of the recent extreme drought on freshwater wetland habitats in the Central Valley, the benefits of incentive programs, and the value of using satellite data to track surface water and waterbird habitats. More research is needed to understand subsequent impacts on the freshwater dependent species that rely on these systems and how incentive programs can most strategically support vulnerable species during future extreme drought.
| S-EPMC6056266 | biostudies-literature
Project description:California's millennium drought of 2012-2015 severely impacted the Central Valley aquifer system and caused permanent loss of groundwater and aquifer storage capacity. To quantify these impacts within the southern San Joaquin Valley, we analyze various complementary measurements, including gravity changes from Gravity Recovery and Climate Experiment (GRACE) satellites; vertical land motion from Global Positioning System, interferometric synthetic aperture radar, and extensometer; and groundwater level records. The interferometric data set acquired by the Sentinel-1 satellite only spans the period January 2015 and October 2017, while the other data sets span the entire drought period. Using GRACE observations, we find an average groundwater loss of 6.1 ± 2.3 km3/year as a lower bound estimate for the San Joaquin Valley, amounting to a total volume of 24.2 ± 9.3 km3 lost during the period October 2011 to September 2015. This is consistent with the total volume of 29.25 ± 8.7 km3, estimated using only Global Positioning System deformation data. Our results highlight the advantage of using vertical land motion data to evaluate groundwater loss and thus fill the gaps between GRACE and GRACE-Follow-On missions and complement their estimates. We further determine that 0.4-3.25% of the aquifer system storage capacity is permanently lost during this drought period. Comparing groundwater level and vertical land motion data following September 2015, we determine an equilibration time of 0.5-1.5 years for groundwater levels within aquitard and aquifer units, during which residual compaction of aquitard and land subsidence continues beyond the drought period. We suggest that such studies can advance the knowledge of evolving groundwater resources, enabling managers and decision makers to better assess water demand and supply during and in-between drought periods.
| S-EPMC6559157 | biostudies-literature
Project description:Spatial estimates of crop evapotranspiration with high accuracy from the field to watershed scale have become increasingly important for water management, particularly over irrigated agriculture in semiarid regions. Here, we provide a comprehensive assessment on patterns of annual agricultural water use over California's Central Valley, using 30-m daily evapotranspiration estimates based on Landsat satellite data. A semiempirical Priestley-Taylor approach was locally optimized and cross-validated with available field measurements for major crops including alfalfa, almond, citrus, corn, pasture, and rice. The evapotranspiration estimates explained >70% variance in daily measurements from independent sites with an RMSE of 0.88 mm day-1. When aggregated over the Valley, we estimated an average evapotranspiration of 820 ± 290 mm yr-1 in 2014. Agricultural water use varied significantly across and within crop types, with a coefficient of variation ranging from 8% for Rice (1,110 ± 85 mm yr-1) to 59% for Pistachio (592 ± 352 mm yr-1). Total water uses in 2016 increased by 9.6%, as compared to 2014, mostly because of land-use conversion from fallow/idle land to cropland. Analysis across 134 Groundwater Sustainability Agencies (GSAs) further showed a large variation of agricultural evapotranspiration among and within GSAs, especially for tree crops, e.g., almond evapotranspiration ranging from 339 ± 80 mm yr-1 in Tracy to 1,240 ± 136 mm yr-1 in Tri-County Water Authority. Continuous monitoring and assessment of the dynamics and spatial heterogeneity of agricultural evapotranspiration provide data-driven guidance for more effective land use and water planning across scales.
| S-EPMC8519118 | biostudies-literature
Project description:ObjectivesCalifornia Senate Bill 41 (SB41), effective January 2012, is a human immunodeficiency virus/hepatitis C virus prevention measure designed to expand syringe access among injection drug users (IDUs) by allowing pharmacies to sell syringes without a prescription. This study assesses self-reported implementation of SB41 and characterizes barriers amenable to intervention.DesignInterviewer-administered survey.Setting and participantsFresno and Kern Counties, CA. Pharmacists and other pharmacy staff (n = 404) at 212 pharmacies.Outcome measureSelf-reported nonprescription pharmacy sales to known or suspected IDUs.ResultsOverall, 29.3% of participants said their pharmacy would sell nonprescription syringes to a known or suspected IDU, whereas a far higher proportion (79.3%) would sell nonprescription syringes to a person with diabetes. More than one-half said that their pharmacy requires nonprescription syringe purchasers to enter their signature and name and address in a log book although that is not required under SB41. Fewer than 2 out of 3 participants (61.1%) knew that it is legal to sell nonprescription syringes to IDUs. That knowledge, as well as having syringe sales practices based on both store policy and discretion, were positively associated with IDU syringe sales after controlling for other factors. Working at an independent pharmacy, agreeing that only people with "medical conditions" such as diabetes should be able to buy syringes, and viewing syringe sales to IDUs as "not good business" were independently but negatively associated with IDU syringe sales.ConclusionThis study complements an earlier syringe purchase trial documenting low participation in voluntary nonprescription syringe sales under SB41 in Fresno and Kern Counties. In the absence of legislation requiring mandatory syringe sales, interventions should be developed to increase knowledge of the law and frame addiction as a medical condition, with a special focus on independent pharmacies. Informational interventions should stress the need to eliminate log book documentation requirements, which may serve as a barrier to IDU purchase.
| S-EPMC5668169 | biostudies-literature
Project description:Surface deformation in California's Central Valley (CV) has long been linked to changes in groundwater storage. Recent advances in remote sensing have enabled the mapping of CV deformation and associated changes in groundwater resources at increasingly higher spatiotemporal resolution. Here, we use interferometric synthetic aperture radar (InSAR) from the Sentinel-1 missions, augmented by continuous Global Positioning System (cGPS) positioning, to characterize the surface deformation of the San Joaquin Valley (SJV, southern two-thirds of the CV) for consecutive dry (2016) and wet (2017) water years. We separate trends and seasonal oscillations in deformation time series and interpret them in the context of surface and groundwater hydrology. We find that subsidence rates in 2016 (mean -42.0 mm/yr; peak -345 mm/yr) are twice that in 2017 (mean -20.4 mm/yr; peak -177 mm/yr), consistent with increased groundwater pumping in 2016 to offset the loss of surface-water deliveries. Locations of greatest subsidence migrated outwards from the valley axis in the wetter 2017 water year, possibly reflecting a surplus of surface-water supplies in the lowest portions of the SJV. Patterns in the amplitude of seasonal deformation and the timing of peak seasonal uplift reveal entry points and potential pathways for groundwater recharge into the SJV and subsequent groundwater flow within the aquifer. This study provides novel insight into the SJV aquifer system that can be used to constrain groundwater flow and subsidence models, which has relevance to groundwater management in the context of California's 2014 Sustainable Groundwater Management Act (SGMA).
| S-EPMC8047915 | biostudies-literature
Project description:BackgroundPyrethroid pesticide use is increasing worldwide, although the full extent of associated health effects is unknown. An epigenome-wide association study (EWAS) with exploratory pathway analysis may help identify potential pyrethroid-related health effects.MethodsWe performed an exploratory EWAS of chronic ambient pyrethroid exposure using control participants' blood in the Parkinson's Environment and Genes Study in the Central Valley of California (N = 237). We estimated associations of living and working near agricultural pyrethroid pesticide applications in the past 5 years (binary) with site-specific differential methylation, and used a false discovery rate (FDR) cut off of 0.05 for significance. We controlled for age, sex, education, cell count, and an ancestral marker for Hispanic ethnicity. We normalized methylation values for Type I/II probe bias using Beta-Mixture Quantile (BMIQ) normalization, filtered out cross-reactive probes, and evaluated for remaining bias with Surrogate Variable Analysis (SVA). We also evaluated the effects of controlling for cell count and normalizing for Type I/II probe bias by comparing changes in effect estimates and p-values for the top hits across BMIQ and GenomeStudio normalization methods, and controlling for cell count. To facilitate broader interpretation, we annotated genes to the CpG sites and performed gene set overrepresentation analysis, using genes annotated to CpG sites that were associated with pyrethroids at a raw p < 0.05, and controlling for background representation of CpG sites on the chip. We did this for both a biological process context (Gene Ontology terms) using missMethyl, and a disease set context using WebGestalt. For these gene set overrepresentation analyses we also used an FDR cut off of 0.05 for significance of gene sets.ResultsAfter controlling for cell count and applying BMIQ normalization, 4 CpG sites were differentially methylated in relation to pyrethroid exposures. When using GenomeStudio's Illumina normalization, 415 CpG sites were differentially methylated, including all four identified with the BMIQ method. In the gene set overrepresentation analyses, we identified 6 GO terms using BMIQ normalization, and 76 using Illumina normalization, including the 6 identified by BMIQ. For disease sets, we identified signals for Alzheimer's disease, leukemia and several other cancers, diabetes, birth defects, and other diseases, for both normalization methods. We identified minimal changes in effect estimates after controlling for cell count, and controlling for cell count generally weakened p-values. BMIQ normalization, however, resulted in different beta coefficients and weakened p-values.ConclusionsChronic ambient pyrethroid exposure is associated with differential methylation at CpG sites that annotate to a wide variety of disease states and biological mechanisms that align with prior research. However, this EWAS also implicates several novel diseases for future investigation, and highlights the relative importance of different background normalization methods in identifying associations.
| S-EPMC7492449 | biostudies-literature
Project description:Chlorpyrifos, an acetylcholinesterase inhibitor (ACI), is one of the most widely used insecticides in the world, and is generally recognized to be a moderate human neurotoxin. This paper reports a distributional environmental justice (dEJ) analysis of chlorpyrifos use in California's Central Valley, examining the way distributions of environmental risks are associated with race, ethnicity, class, gender, and other systems of structural oppression. Spatial data on chlorpyrifos use were retrieved from California's Department of Pesticide Registration public pesticide use records for 2011-2015. These data were combined with demographic data for the Central Valley from the American Community Survey (ACS). Spatial regression models were used to estimate effects of demographic covariates on local chlorpyrifos use. A novel bootstrap method was used to account for measurement error in the ACS estimates. This study finds consistent evidence that Hispanic population proportion is associated with increased local chlorpyrifos use. A 10-point increase in Hispanic proportion is associated with an estimated 1.05-1.4-fold increase in local chlorpyrifos use across Census tract models. By contrast, effects of agricultural employment and poverty on local chlorpyrifos use are ambiguous and inconsistent between Census tracts and Census-designated places.
| S-EPMC7177971 | biostudies-literature
Project description:Changes in terrestrial water content cause elastic deformation of the Earth's crust. This deformation is thought to play a role in modulating crustal stress and seismicity in regions where large water storage fluctuations occur. Groundwater is an important component of total water storage change in California, helping to drive annual water storage fluctuations and loss during periods of drought. Here we use direct estimates of groundwater volume loss during the 2007-2010 drought in California's Central Valley obtained from high resolution Interferometric Synthetic Aperture Radar-based vertical land motion data to investigate the effect of groundwater volume change on the evolution of the stress field. We show that GPS-derived elastic load models may not capture the contribution of groundwater to terrestrial water loading, resulting in an underestimation of nontectonic crustal stress change. We find that groundwater unloading during the drought causes Coulomb stress change of up to 5.5 kPa and seasonal fluctuations of up to 2.6 kPa at seismogenic depth. We find that faults near the Valley show the largest stress change and the San Andreas fault experiences only ~40 Pa of Coulomb stress change over the course of a year from groundwater storage change. Annual Coulomb stress change peaks dominantly in the fall, when the groundwater level is low; however, some faults experience peak stress in the spring when groundwater levels are higher. Additionally, we find that periods of increased stress correlate with higher than average seismic moment release but are not correlated with an increase in the number of earthquakes. This indicates groundwater loading likely contributes to nontectonic loading of faults, especially near the Valley edge, but is not a dominant factor in modulation of seismicity in California because the amplitude of stress change declines rapidly with distance from the Valley. By carefully quantifying and spatially locating groundwater fluctuations, we will improve our understanding of what drives nontectonic stress and forces that modulate seismicity in California.
| S-EPMC7607378 | biostudies-literature