Machine learning based downscaling of GRACE-estimated groundwater in Central Valley, California

Science of the Total Environment (Elsevier) | January 9th, 2023

California's Central Valley, one of the most agriculturally productive regions, is also one of the most stressed aquifers in the world due to anthropogenic groundwater ov

California's Central Valley, one of the most agriculturally productive regions, is also one of the most stressed aquifers in the world due to anthropogenic groundwater over-extraction primarily for irrigation. Groundwater depletion is further exacerbated by climate-driven droughts. Gravity Recovery and Climate Experiment (GRACE) satellite gravimetry has demonstrated the feasibility of quantifying global groundwater storage changes at uniform monthly sampling, though at a coarse resolution and is thus impractical for effective water resources management. Here, we employ the Random Forest machine learning algorithm to establish empirical relationships between GRACE-derived groundwater storage and in situ groundwater level variations over the Central Valley during 2002–2016 and achieved spatial downscaling of GRACE-observed groundwater storage changes from a few hundred km to 5 km. Validations of our modeled groundwater level with in situ groundwater level indicate excellent Nash-Sutcliffe Efficiency coefficients ranging from 0.94 to 0.97. In addition, the secular components of modeled groundwater show good agreements with those of vertical displacements observed by GPS, and CryoSat-2 radar altimetry measurements and is perfectly consistent with findings from previous studies. Our estimated groundwater loss is about 30 km3 from 2002 to 2016, which also agrees well with previous studies in Central Valley. We find the maximum groundwater storage loss rates of −5.7 ± 1.2 km3 yr−1 and -9.8 ± 1.7 km3 yr−1 occurred during the extended drought periods of January 2007–December 2009, and October 2011–September 2015, respectively while Central Valley also experienced groundwater recharges during prolonged flood episodes. The 5-km resolution Central Valley-wide groundwater storage trends reveal that groundwater depletion occurs mostly in southern San Joaquin Valley collocated with severe land subsidence due to aquifer compaction from excessive groundwater over withdrawal.

Managed Aquifer Recharge and the U.S. Army Corps of Engineers: Water Security through Resilience

U.S. Army Corps of Engineers (USACE) | May 14th, 2020

Microplastics in Lake Mead National Recreation Area

U.S. Geological Survey (USGS) | October 9th, 2019

  This dataset describes the quantity and morphology of microplastics in water, surficial sediment, sediment core, fish, and shellfish samples from Lake Mead Nation

  This dataset describes the quantity and morphology of microplastics in water, surficial sediment, sediment core, fish, and shellfish samples from Lake Mead National Recreation Area (Nevada/Arizona). Water and surficial sediment samples were collected once at 9 locations. A sediment core (33 cm long) was extracted from Las Vegas Bay to assess changes in microplastic deposition over time. Striped bass (Morone saxatilis), common carp (Cyprinus carpio), quagga mussels (Dreissena bugensis), and Asian clams (Corbicula fluminea) were sampled at a subset of locations to assess biological uptake of microplastics. Sampling and analysis methods are described in the Processing Steps section of the metadata. All samples were collected in March 2017 except the sediment core, which was collected in March 2018.  

Modeling Land Subsidence Using InSAR and Airborne Electromagnetic Data

American Geophysical Union (AGU) | March 13th, 2019

Land subsidence as a result of groundwater overpumping in the San Joaquin Valley, California, is associated with the loss of groundwater storage and aquifer contaminatio

Land subsidence as a result of groundwater overpumping in the San Joaquin Valley, California, is associated with the loss of groundwater storage and aquifer contamination. Although the physical processes governing land subsidence are well understood, building predictive models of subsidence is challenging because so much subsurface information is required to do so accurately. For the first time, we integrate airborne electromagnetic data, representing the subsurface, with subsidence data, mapped by interferometric synthetic aperture radar (InSAR), to model deformation. By combining both data sets, we are able to solve for hydrologic and geophysical properties of the subsurface to effectively model the complex spatiotemporal process of deformation. The resulting model reveals that roughly 3 m of subsidence has occurred at one location of our study area from 1990 to 2018. This model also allows us to predict subsidence more accurately under future hydrologic scenarios, which is needed to develop plans for sustainable groundwater use.

Mountain rock glaciers contain globally significant water stores

Nature Portfolio (Springer Nature) | February 12th, 2018

Glacier- and snowpack-derived meltwaters are threatened by climate change. Features such as rock glaciers (RGs) are climatically more resilient than glaciers and

Glacier- and snowpack-derived meltwaters are threatened by climate change. Features such as rock glaciers (RGs) are climatically more resilient than glaciers and potentially contain hydrologically valuable ice volumes. However, while the distribution and hydrological significance of glaciers is well studied, RGs have received comparatively little attention. Here, we present the first near-global RG database (RGDB) through an analysis of current inventories and this contains >73,000 RGs. Using the RGDB, we identify key data-deficient regions as research priorities (e.g., Central Asia). We provide the first approximation of near-global RG water volume equivalent and this is 83.72 ± 16.74 Gt. Excluding the Antarctic and Subantarctic, Greenland Periphery, and regions lacking data, we estimate a near-global RG to glacier water volume equivalent ratio of 1:456. Significant RG water stores occur in arid and semi-arid regions (e.g., South Asia East, 1:57). These results represent a first-order approximation. Uncertainty in the water storage estimates includes errors within the RGDB, inherent flaws in the meta-analysis methodology, and RG thickness estimation. Here, only errors associated with the assumption of RG ice content are quantified and overall uncertainty is likely larger than that quantified. We suggest that RG water stores will become increasingly important under future climate warming.

Movement of synthetic organic compounds in the food web after the introduction of invasive quagga mussels (Dreissena bugensis) in Lake Mead, Nevada and Arizona, USA

Publisher not available | August 21st, 2020

Introductions of dreissenid mussels in North America have been a significant concern over the last few decades. This study assessed the distribution of synthetic organic

Introductions of dreissenid mussels in North America have been a significant concern over the last few decades. This study assessed the distribution of synthetic organic compounds (SOCs) in the food web of Lake Mead, Nevada/Arizona, USA and how this distribution was influenced by the introduction of invasive quagga mussels. A clear spatial gradient of SOC concentrations in water was observed between lake basins downstream of populated areas and more rural areas. Within the food web, trophic magnification factors (TMF) indicated statistically significant biomagnification for nine, and biodilution for two, of 22 SOCs examined. The highest value recorded was for PCB 118 (TMF, 5.14), and biomagnification of methyl triclosan (TMF, 3.85) was also apparent. Biodilution was observed for Tonalide® (0.06) and Galaxolide® (0.38). Total SOC concentration in quagga mussels was higher than in three pelagic fishes. Also, 19 of 20 SOC examined in Largemouth Bass (Micropterus salmoides) had substantially lower concentrations in 2013, when quagga mussels had become well established, than in 2007/08, soon after quagga mussels were introduced. Estimates of SOC concentrations in the water column and quagga mussels suggest that a considerable portion (~10.5%) of the SOC mass in the lake has shifted from the pelagic to the benthic environments due to quagga mussel growth. These observations suggest that benthic species, such as the endangered Razorback Sucker, may be experiencing increased risk of SOC exposure. In addition, stable isotope analysis (carbon and nitrogen) indicated a decrease in the nutritional value of zooplankton to consumers (e.g., Razorback Sucker larvae) since quagga mussels became established. These changes could affect Razorback Sucker larval survival and recruitment. Results from this study strongly suggest that the introduction of quagga mussels has greatly altered the dynamics of SOCs and other processes in the food web of Lake Mead.

Municipal Service Review and Sphere of Influence Update for the Orange County Water District Including a Feasibility Analysis of the Potential Consolidation of Orange County Water District and Municipal Water District of Orange County

Local Agency Formation Commission of Orange County | November 15th, 2024

North of Delta Offstream Storage (NODOS) Investigation Highlights (Sites Reservoir)

California Department of Water Resources (DWR) | May 28th, 2014

The California Department of Water Resources and the U.S. Bureau of Reclamation, working in cooperation with other federal, state, and local agencies, are studying the po

The California Department of Water Resources and the U.S. Bureau of Reclamation, working in cooperation with other federal, state, and local agencies, are studying the potential feasibility of alternative plans to build an offstream surface storage north of the Sacramento-San Joaquin Delta as part of the North-of-the-Delta Offstream Storage (NODOS) Investigation. NODOS would provide a robust set of benefits, including water supply reliability for municipal and industrial uses, agriculture, and wildlife refuges; ecosystem enhancement actions to improve fish survival in major northern California rivers and the Sacramento-San Joaquin Delta (Delta); water quality improvements for Delta water users and estuarine species; flexible hydropower generation to support renewable energy sources such as wind and solar; recreation opportunities at the new reservoir and improved recreation at existing reservoirs; and local flood damage reduction below the new reservoir. Total water supply benefits of NODOS would be up to 500 thousand acre-feet (TAF) per year on average and over 600 TAF per year during dry and critical years. The mix of NODOS benefits would also support improved flexibility and long-term viability of the Central Valley Project (CVP) and State Water Project (SWP). As the current drought is showing, flexibility of these projects is impaired during multiple dry years or droughts. In addition to providing the benefits described above, NODOS would improve CVP and SWP flexibility by increasing water in storage, including during drought conditions. Average annual improved storage would be up to 1.4 million acre-feet (MAF); annual drought period storage would be improved by up to 1.1 MAF. The potential environmental effects of constructing and operating NODOS are evaluated and potential mitigation measures are described in the NODOS Preliminary Administrative Draft Environmental Impact Report.  The preliminary benefits and costs are presented in the NODOS Preliminary Design and Cost Estimate Report.  

North-of-the-Delta Offstream Storage Investigation (Sites Reservoir) 2013 Progress Report

U.S. Bureau of Reclamation (USBR) | January 1st, 2015

The North-of-the-Delta Off Stream Storage (NODOS) Investigation is a Feasibility Study being performed the Bureau of Reclamation and Sites Project Authority, in partnersh

The North-of-the-Delta Off Stream Storage (NODOS) Investigation is a Feasibility Study being performed the Bureau of Reclamation and Sites Project Authority, in partnership with local interests and pursuant to the CALFED Bay-Delta Program Programmatic Environmental Impact Statement/Report Record of Decision. The NODOS Investigation is evaluating potential offstream surface water storage projects in the upper Sacramento River Basin that could increase surface water storage capacity in the Sacramento River Basin as one of several actions to improve water supply reliability, renewable power integration, Delta water quality, and critical fish populations within the Bay-Delta watersheds. The NODOS Investigation is one of five surface water storage studies recommended in the CALFED PEIS/EIR Record of Decision.

Oroville Dam Safety Comprehensive Needs Assessment Summary

California Department of Water Resources (DWR) | October 30th, 2020

Oroville Dam, located on the Feather River in Butte County, is a key facility of the California State Water Project (SWP). Completed in 1967, it is owned and operated by

Oroville Dam, located on the Feather River in Butte County, is a key facility of the California State Water Project (SWP). Completed in 1967, it is owned and operated by the California Department of Water Resources (DWR). In February 2017, both the gated main spillway and the ungated emergency spillway suffered significant erosion scour damage while releasing flood waters that had flowed into Lake Oroville. Concerns for the stability of the spillway crest structures resulted in the temporary evacuation of 188,000 residents downstream of the dam. Over the next few months, flood waters were successfully managed by making controlled reservoir releases down the damaged gated main spillway through May 2017 when the gates were closed for the year and DWR began repairs to the two spillways. By the fall of 2018, the entire 3,000-foot-long chute for the gated main spillway had been completely reconstructed, and major erosion-resistant armoring had been added to the emergency spillway. The repairs resulted in making these two spillways robust structures meeting modern engineering standards.