Priorities for California’s Water -- Stewarding the Wet Years

Public Policy Institute of California (PPIC) | November 2nd, 2023

The 2023 water year provided a case study of California’s increasingly volatile climate, with large swings between wet and dry conditions both within and between years.

The 2023 water year provided a case study of California’s increasingly volatile climate, with large swings between wet and dry conditions both within and between years. It highlighted our need to better navigate multiple imperatives: storing more water during intense wet periods to build water supply reliability, protecting communities and infrastructure against the threat of increasingly damaging floods, and taking better advantage of wet years to improve the health of freshwater ecosystems and native fish and wildlife.

Procedures to evaluate sea-level change: impacts, responses, and adaptation

U.S. Army Corps of Engineers (USACE) | June 30th, 2014

Progress on Incorporating Climate Change into Planning and Management of California’s Water Resources

California Department of Water Resources (DWR) | July 9th, 2006

On June 1, 2005, Governor Arnold Schwarzenegger issued Executive Order S-3-05 establishing greenhouse gas emissions targets for California and requiring biennial reports

On June 1, 2005, Governor Arnold Schwarzenegger issued Executive Order S-3-05 establishing greenhouse gas emissions targets for California and requiring biennial reports on potential climate change effects on several areas, including water resources. The Governor established a Climate Action Team (CAT) to guide the reporting efforts. The CAT selected four climate change scenarios that reflect two greenhouse gas emissions scenarios represented by two Global Climate Models (GCMs). The CAT requested that those four climate change scenarios be used whenever possible in the climate change reporting efforts. This report is the Department of Water Resources response to the Executive Order. This report describes progress made incorporating climate change into existing water resources planning and management tools and methodologies.

Projected 21st Century Coastal Flooding in the Southern California Bight. Part 1: Development of the Third Generation CoSMoSModel

Journal of Marine Science and Engineering (MDPI) | May 24th, 2018

Due to the effects of climate change over the course of the next century, the combination of rising sea levels, severe storms, and coastal change will threaten the susta

Due to the effects of climate change over the course of the next century, the combination of rising sea levels, severe storms, and coastal change will threaten the sustainability of coastal communities, development, and ecosystems as we know them today. To clearly identify coastal vulnerabilities and develop appropriate adaptation strategies due to projected increased levels of coastal flooding and erosion, coastal managers need local-scale hazards projections using the best available climate and coastal science. In collaboration with leading scientists world-wide, the USGS designed the Coastal Storm Modeling System (CoSMoS) to assess the coastal impacts of climate change for the California coast, including the combination of sea-level rise, storms, and coastal change. In this project, we directly address the needs of coastal resource managers in Southern California by integrating a vast range of global climate change projections in a thorough and comprehensive numerical modeling framework. In Part 1 of a two-part submission on CoSMoS, methods and the latest improvements are discussed, and an example of hazard projections is presented. Click here for Part 2.

Projected 21st Century Coastal Flooding in the Southern California Bight. Part 2: Tools for Assessing Climate Change-Driven Coastal Hazards and Socio-Economic Impacts

Journal of Marine Science and Engineering (MDPI) | July 2nd, 2018

This paper is the second of two that describes the Coastal Storm Modeling System (CoSMoS) approach for quantifying physical hazards and socio-economic hazard exposure in

This paper is the second of two that describes the Coastal Storm Modeling System (CoSMoS) approach for quantifying physical hazards and socio-economic hazard exposure in coastal zones affected by sea-level rise and changing coastal storms. The modelling approach, presented in Part 1, downscales atmospheric global-scale projections to local scale coastal flood impacts by deterministically computing the combined hazards of sea-level rise, waves, storm surges, astronomic tides, fluvial discharges, and changes in shoreline positions. The method is demonstrated through an application to Southern California, United States, where the shoreline is a mix of bluffs, beaches, highly managed coastal communities, and infrastructure of high economic value. Results show that inclusion of 100-year projected coastal storms will increase flooding by 9–350% (an additional average 53.0 16.0 km2) in addition to a 25–500 cm sea-level rise. The greater flooding extents translate to a 55–110% increase in residential impact and a 40–90% increase in building replacement costs. To communicate hazards and ranges in socio-economic exposures to these hazards, a set of tools were collaboratively designed and tested with stakeholders and policy-makers; these tools consist of two web-based mapping and analytic applications as well as virtual reality visualizations. To reach a larger audience and enhance usability of the data, outreach and engagement included workshop-style trainings for targeted end-users and innovative applications of the virtual reality visualizations.

Projected Brackish Water Desalination Projects in California

California Department of Water Resources (DWR) | February 20th, 2024

California’s Water Supply Strategy: Adapting to a Hotter, Drier Future (Water Supply Strategy), adopted by the Newsom Administration in 2022, identifies multiple action

California’s Water Supply Strategy: Adapting to a Hotter, Drier Future (Water Supply Strategy), adopted by the Newsom Administration in 2022, identifies multiple actions necessary to bolster water supply reliability in the face of climate change. The first set of actions drive the development of new water supplies and set explicit goals for expanding the production of both recycled and desalinated water. Action 1.2 includes specific targets for expanded brackish water desalination: 28,000 acre-feet by 2030, and 84,000 acre-feet by 2040. The Water Supply Strategy identifies five steps toward achieving this goal.

Projecting groundwater storage changes in California’s Central Valley

Nature Portfolio (Springer Nature) | August 27th, 2018

Accurate and detailed knowledge of California’s groundwater is of paramount importance for statewide water resources planning and management, and to sustain a

Accurate and detailed knowledge of California’s groundwater is of paramount importance for statewide water resources planning and management, and to sustain a multi-billion-dollar agriculture industry during prolonged droughts. In this study, we use water supply and demand information from California’s Department of Water Resources to develop an aggregate groundwater storage model for California’s Central Valley. The model is evaluated against 34 years of historic estimates of changes in groundwater storage derived from the United States Geological Survey’s Central Valley Hydrologic Model (USGS CVHM) and NASA’s Gravity Recovery and Climate Experiment (NASA GRACE) satellites. The calibrated model is then applied to predict future changes in groundwater storage for the years 2015–2050 under various precipitation scenarios from downscaled climate projections. We also discuss and project potential management strategies across different annual supply and demand variables and how they affect changes in groundwater storage. All simulations support the need for collective statewide management intervention to prevent continued depletion of groundwater availability.

Pure Water Southern California

Metropolitan Water District of Southern California (MWD) | March 29th, 2024

Putting Adaptive Management into Practice: Incorporating Quantitative Metrics into Sustainable Groundwater Management

Stanford University | March 4th, 2019

Groundwater is a critical resource in California, serving as a reserve during droughts that are expected to be increasingly frequent and severe as climate change progres

Groundwater is a critical resource in California, serving as a reserve during droughts that are expected to be increasingly frequent and severe as climate change progresses. Adaptive management – revising management practices based on monitoring of progress toward pre-established quantitative metrics of performance – is widely viewed as an effective approach to managing water and other natural resources under conditions of uncertainty. However, linking performance metrics effectively with decision-making processes is often challenging, requiring careful consideration of institutional factors that may limit an agency’s ability to act based on new information. Governance arrangements that enable adaptive management must balance the need for flexibility as conditions change with a preference among water users for stable rules. The Sustainable Groundwater Management Act (SGMA) of 2014 – California’s first statewide framework for managing groundwater – incorporates many elements of adaptive management, including requirements to manage groundwater according to quantitative metrics of performance. Under regulations guiding the development of Groundwater Sustainability Plans (GSPs), newly formed Groundwater Sustainability Agencies (GSAs) must define measurable objectives, minimum thresholds and interim milestones to eliminate six “undesirable results” by 2040 or 2042, depending upon the basin. Yet, the creation of these metrics alone will be insufficient to achieve sustainable management of California’s groundwater; institutional arrangements must support their use to guide management actions. To provide insight into the design and use of metrics as guides to decision-making, this report draws upon the experiences of four special act districts that had authority to manage groundwater prior to SGMA. These include two primarily urban water agencies, Santa Clara Valley Water District (SCVWD) and Zone 7 Water Agency (Zone 7) and two agencies with significant pumping for agricultural use, Fox Canyon Groundwater Management Agency (FCGMA) and Pajaro Valley Water Management Agency (PVWMA). This report analyzes how these agencies used quantitative metrics in their groundwater management plans prior to SGMA and identifies institutional factors that constrained or enabled the adjustment of management actions in response to changing conditions during the 2012-2016 drought. Although the metrics employed by these agencies differ from those required under GSP regulations, these agencies’ experiences still offer important insights for GSAs seeking to develop metrics and integrate them into decision making.

Rapid emergence of climate change in environmental drivers of marine ecosystems

Nature Portfolio (Springer Nature) | March 7th, 2017

Climate change is expected to modify ecological responses in the ocean, with the potential for important effects on the ecosystem services provided to humankind

Climate change is expected to modify ecological responses in the ocean, with the potential for important effects on the ecosystem services provided to humankind. Here we address the question of how rapidly multiple drivers of marine ecosystem change develop in the future ocean. By analysing an ensemble of models we find that, within the next 15 years, the climate change-driven trends in multiple ecosystem drivers emerge from the background of natural variability in 55% of the ocean and propagate rapidly to encompass 86% of the ocean by 2050 under a ‘business-as-usual’ scenario. However, we also demonstrate that the exposure of marine ecosystems to climate change-induced stress can be drastically reduced via climate mitigation measures; with mitigation, the proportion of ocean susceptible to multiple drivers within the next 15 years is reduced to 34%. Mitigation slows the pace at which multiple drivers emerge, allowing an additional 20 years for adaptation in marine ecological and socio-economic systems alike.