Tracking California’s sinking coast from space: Implications for relative sea-level rise

American Association for the Advancement of Science (AAAS) | July 31st, 2020

Coastal vertical land motion affects projections of sea-level rise, and subsidence exacerbates flooding hazards. Along the ~1350-km California coastline, record

Coastal vertical land motion affects projections of sea-level rise, and subsidence exacerbates flooding hazards. Along the ~1350-km California coastline, records of high-resolution vertical land motion rates are scarce due to sparse instrumentation, and hazards to coastal communities are underestimated. Here, we considered a ~100-km-wide swath of land along California’s coast and performed a multitemporal interferometric synthetic aperture radar (InSAR) analysis of large datasets, obtaining estimates of vertical land motion rates for California’s entire coast at ~100-m dimensions—a ~1000-fold resolution improvement to the previous record. We estimate between 4.3 million and 8.7 million people in California’s coastal communities, including 460,000 to 805,000 in San Francisco, 8000 to 2,300,00 in Los Angeles, and 2,000,000 to 2,300,000 in San Diego, are exposed to subsidence. The unprecedented detail and submillimeter accuracy resolved in our vertical land motion dataset can transform the analysis of natural and anthropogenic changes in relative sea-level and associated hazards.

Tracking California’s striking water storage gains attributed to intensive atmospheric rivers

Journal of Hydrology (Elsevier) | February 5th, 2025

California is highly vulnerable to extreme precipitation events due to the dense landfall of atmospheric rivers (ARs) during the winter months, often resulting in catastr

California is highly vulnerable to extreme precipitation events due to the dense landfall of atmospheric rivers (ARs) during the winter months, often resulting in catastrophic consequences such as widespread floods, mudslides, and landslides. This study focuses on the recovery of daily variations in AR-driven terrestrial water storage (TWS), which produces geodetically detectable ground subsidence. We invert GNSS vertical positions to obtain daily estimates of equivalent water height (EWH) through a variational Bayesian principal component analysis (vbPCA) based inversion scheme and track significant water gains during record-setting winter months in four water years (WYs) 2011, 2017, 2019, and 2023. These precipitation extremes have resulted in a substantial short-term increase in water storage, as evidenced by the multi-source EWH datasets (GNSS, GRACE, and NLDAS). Notably, WY 2023 experienced the highest snowfall due to the landfalls of high-density, high-category ARs, while WY 2017 recorded the highest precipitation totals, driven by the most frequent occurrence of hazardous ARs. Our findings further highlight that GNSS can accurately detect exceptionally wet hydrological events on short time scales, benefiting from an improved signal-to-noise ratio due to substantial increase in water storage. The results also indicate that while these extreme water years can help alleviate surface subsidence in the Central Valley caused by groundwater overexploitation, it is insufficient to alter California’s heavy reliance on groundwater for its intensive agricultural activities. Our findings demonstrate that GNSS is successful in tracking prodigious water increases from short-term precipitation extremes that are weaker than powerful hurricanes, illuminating the prospect of GNSS in supporting water management and flood preparedness.

Tracking Organic Matter in Delta Drinking Water

CALFED | April 1st, 2008

Tracking Where Water Goes in a Changing Sacramento–San Joaquin Delta

Public Policy Institute of California (PPIC) | May 26th, 2022

Click here for the accompanying Technical Appendix.

Click here for the accompanying Technical Appendix.

Tracking Where Water Goes in a Changing Sacramento–San Joaquin Delta Technical Appendix: Methods and Detailed Results for 1980–2021

Public Policy Institute of California (PPIC) | May 26th, 2022

Our goal is to provide water policymakers, managers, and regulators with information that will be helpful in managing the Delta and its watershed for multiple objectives

Our goal is to provide water policymakers, managers, and regulators with information that will be helpful in managing the Delta and its watershed for multiple objectives as warming conditions increase water demand, reduce snowpack, and make it harder to balance these objectives. An accompanying policy brief summarizes the findings presented here and highlights the major policy recommendations. This appendix provides details and evidence to support those recommendations and is intended for both a technical and policy audience. In the following sections we first review our approach for categorizing water flows in the watershed, and we review the caveats and limitations of the analysis. We next present key results and discuss several important watershed trends. We then review the management challenges of changing conditions in the Delta in wet and dry years through the lens of detailed water accounting. We conclude with implications for policy and management, including recommendations to improve watershed accounting and adapt the regulatory and management framework to the changing conditions in the watershed. All data assembled for this study, along with the sources and methods used, are detailed in the accompanying PPIC Delta Water Accounting spreadsheets.

Tracy Subbasin Groundwater Sustainability Plan

County of San Joaquin GSA | November 1st, 2021

The Tracy Subbasin boundaries follow the Old River on the northwest, the Coastal Range on the southwest and south, and the San Joaquin River on the east. The southeast bo

The Tracy Subbasin boundaries follow the Old River on the northwest, the Coastal Range on the southwest and south, and the San Joaquin River on the east. The southeast boundary of the Subbasin, along the San Joaquin-Stanislaus county line, follows irregular water district boundaries. The Subbasin is almost entirely with San Joaquin County but includes a small triangular portion of Alameda County. About one-half of the Subbasin is a mix of Delta islands (mostly agriculture) and waterways while the other half is comprised of urban and agricultural communities (Non-Delta areas).

Trade-offs across the water-energy-food nexus: A triple bottom line sustainability assessment of desalination for agriculture in the San Quintín Valley, Mexico

Environmental Science & Policy (Elsevier) | September 30th, 2020

This paper introduces a novel triple bottom line sustainability assessment to evaluate the water-energy-food nexus of desalination for agriculture. Falling technology cos

This paper introduces a novel triple bottom line sustainability assessment to evaluate the water-energy-food nexus of desalination for agriculture. Falling technology costs and rising water scarcity worldwide make desalination an increasingly attractive proposition, and agriculture is one of the main sectors grappling with its potential impacts. To explore this issue, we combine a wide range of primary and secondary environmental, economic, and social data with a triple bottom line / WEF nexus analysis, to demonstrate both the holistic sustainability impacts of desalination for agriculture, and the multi-sectoral policy environment within which desalination is adopted. We apply this approach to 54 privately-owned desalination plants that treat brackish groundwater for agricultural use in the San Quintín Valley of Baja California, Mexico. We find that subsidized energy for local agribusinesses plays an important role in making desalination economically viable in the region. This in turn fuels a large agricultural export industry that represents a significant virtual water transfer to the US market. Rapid population growth in the area driven by agricultural labor needs exacerbates the issues of social equity and sustainability that these subsidies and transfers raise. We conclude with a discussion of how to manage these identified trade-offs across the water-energy-food nexus.

Trading Sustainably: Critical Considerations for Local Groundwater Markets Under the Sustainable Groundwater Management Act

University of California, Berkeley (UC Berkeley) | June 1st, 2017

The Sustainable Groundwater Management Act (SGMA), passed in 2014, is changing the way California manages its groundwater resources. SGMA calls for the creation of loc

The Sustainable Groundwater Management Act (SGMA), passed in 2014, is changing the way California manages its groundwater resources. SGMA calls for the creation of local Groundwater Sustainability Agencies (GSAs) and tasks them with developing and implementing Groundwater Sustainability Plans (GSPs) to achieve sustainable groundwater management. SGMA offers GSAs a broad palette of tools to choose from and significant flexibility to tailor their management activities to local conditions and needs. Because it allows GSAs to assign groundwater extraction allocations to pumpers and to authorize transfers of these allocations under certain circumstances, SGMA potentially opens the door for the development of local groundwater markets. In such a market, a willing seller might trade a portion of their groundwater extraction allocation to a willing buyer, allowing the buyer to pump groundwater in the seller’s stead.

Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

European Geosciences Union (EGU) | July 4th, 2012

Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly

Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

Transition from irrigation with untreated wastewater to treated wastewater and associated benefits and risks

Nature Portfolio (Springer Nature) | January 26th, 2025

Investments in “Clean water and sanitation” drive a transition from irrigation with untreated to irrigation with treated wastewater. While this transition reduces man

Investments in “Clean water and sanitation” drive a transition from irrigation with untreated to irrigation with treated wastewater. While this transition reduces many health risks, it may decrease crop yields, and soil carbon storage, cause a release of accumulated pollutants from soils, and increase the spread of antibiotic resistance in the environment. A holistic view on multiple SDGs is necessary to maximize benefits and minimize risks of wastewater treatment for irrigation.