From Climate Traces to Climate Insights: Future Scenarios Analysis for the California Central Valley

California Department of Water Resources (DWR) | October 2nd, 2023

California Water Code Section 10004.6 requires the California Department of Water Resources (DWR) to quantify current and future water conditions in the state. This infor

California Water Code Section 10004.6 requires the California Department of Water Resources (DWR) to quantify current and future water conditions in the state. This information is published in the California Water Plan (Water Plan), which is updated every five years. Water managers and planners constantly face the challenges of planning for an uncertain future where the only constant is change. To address the potential future changes and mitigate the probable risks, water managers must consider and quantify uncertainties and their impacts on water system vulnerability. Although it is not possible to know for certain how population growth, land use decisions, climate, and other factors change over time, water planners must consider these system stressors in long-term planning to evaluate future risks and uncertainty. The Water Plan evaluates many alternative future scenarios as an integral part of its analytical approach to quantify system vulnerability under a range of population and urban growth scenarios, land use, and climate uncertainties.

From Climate-Change Spaghetti to Climate-Change Distributions for 21st Century California

University of California, Davis (UC Davis) | March 1st, 2005

The uncertainties associated with climate-change projections for California are unlikely to disappear anytime soon, and yet important long-term decisions will be needed t

The uncertainties associated with climate-change projections for California are unlikely to disappear anytime soon, and yet important long-term decisions will be needed to accommodate those potential changes. Projection uncertainties have typically been addressedby analysis of a few scenarios, chosen based on availability or to capture the extreme cases among available projections. However, by focusing on more com-mon projections rather than the most extreme projections (using a new resampling method), new insights into current projections emerge: (1) uncertainties associated with future greenhouse-gas emissions are comparable with the differences among climate models, so that neither source of uncertainties should be neglected or underrepresented; (2) twenty-first century temperature projections spread more, overall, than do precipitation scenarios; (3) projections of extremely wet futures for California are true outliers among current projections; and (4) current projections that are warmest tend, overall, to yield a moderately drier California, while the cooler projections yield a some-what wetter future. The resampling approach appliedin this paper also provides a natural opportunity to objectively incorporate measures of model skill and the likelihoods of various emission scenarios into future assessments.

From crisis to connectivity: Renewed thinking about managing California’s water & food supply

California Roundtable on Water and Food Supply (CRWFS) | April 14th, 2014

Modern water management has largely focused on the near-term objectives of a particular user group, be it agriculture, urban, or environment. Over time, competing demands

Modern water management has largely focused on the near-term objectives of a particular user group, be it agriculture, urban, or environment. Over time, competing demands for our finite water resource has led to intractable water conflicts and a water infrastructure that is managed by a highly complex and fragmented network of local, state, and federal institutions. These institutional and water infrastructures abound with missing, broken, or dysfunctional connections between agricultural, urban, and environmental water users, creating negative impacts for all. Addressing these challenges requires a new and strategic approach that is based in understanding the whole system. Fortunately, a shift toward a whole-systems approach is already developing within a number of disciplines that inform water resource management, food supply systems, and environmental stewardship. In this report, From Crisis to Connectivity: Renewed Thinking about Managing California’s Water and Food Supply, the California Roundtable on Water and Food Supply (CRWFS) builds on this shift and identifies the concepts of connectivity and connected benefits: » Connectivity defines the relationships that link the individual parts of a system to form a whole. It recognizes that the actions of one component within a system have an impact, both on the other components of that same system, and upon other, linked systems. The connectivity approach uses this understanding to better align the interactions between human systems (i.e., engineered resource systems, cultural norms, and institutions) and ecosystems (i.e., climatic, chemical and biological systems, and natural resources). This approach proposes that human systems are a central subsystem of the larger ecosystems, rather than systems that exist apart from and only linked to ecosystems. The goal of this alignment is to more effectively design for, and simultaneously achieve, benefits for agricultural and urban users, while ensuring environmental restoration, protection, and stewardship. » The concept of connected benefits refers to achieving simultaneous benefits across all major water users. The idea of connected benefits builds on the positive historical trend from single to dual and multiple benefits that evolved as a way to respond to California’s increasing water management challenges. Based on our assessment of current needs and the patterns of disconnects, we have identified three initial high-priority areas in which we believe the connectivity approach can effect significant change in California’s food and water systems. Each high-priority area has several principles to help guide assessment of water and food issues, as well as design and implementation of solutions.

From Desert Wasteland to Agricultural Wonderland: The Story of Water and Power

Imperial Irrigation District (IID) | October 3rd, 1977

From past patterns to future potential: using historical ecology to inform river restoration on an intermittent California river

Landscape Ecology (Springer) | August 30th, 2015

Although human actions have greatly impacted the river’s extent, baseflow hydrology, and riparian habitats, many ecological attributes persist in more limited form, in

Although human actions have greatly impacted the river’s extent, baseflow hydrology, and riparian habitats, many ecological attributes persist in more limited form, in large part facilitated by these fundamental hydrogeological controls. By drawing on a heretofore untapped dataset of spatially explicit and long-term environmental data, these findings improve our understanding of the river’s historical and current conditions and allow the derivation of reach-differentiated restoration and management opportunities that take advantage of local potential.

From Sediment to Top Predators: Broad Exposure of Polyhalogenated Carbazoles in San Francisco Bay

American Chemical Society (ACS) | January 23rd, 2017

The present study provides the first comprehensive investigation of polyhalogenated carbazoles (PHCZs) contamination in an aquatic ecosystem. PHCZs have been found in soi

The present study provides the first comprehensive investigation of polyhalogenated carbazoles (PHCZs) contamination in an aquatic ecosystem. PHCZs have been found in soil and aquatic sediment from several different regions, but knowledge of their bioaccumulation and trophodynamics is extremely scarce. This work investigated a suite of 11 PHCZ congeners in San Francisco Bay (United States) sediment and organisms, including bivalves (n = 6 composites), sport fish (n = 12 composites), harbor seal blubber (n = 18), and bird eggs (n = 8 composites). The most detectable congeners included 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), 1,3,6-tribromocarbazole (136-BCZ), 1,3,6,8-tetrabromocarbazole (1368-BCZ), and 1,8-dibromo-3,6-dichlorocarbazole (18-B-36-CCZ). The median concentrations of ΣPHCZs were 9.3 ng/g dry weight in sediment and ranged from 33.7 to 164 ng/g lipid weight in various species. Biomagnification was observed from fish to harbor seal and was mainly driven by chlorinated carbazoles, particularly 36-CCZ. Congener compositions of PHCZs differed among species, suggesting that individual congeners may be subject to different bioaccumulation or metabolism in species occupying various trophic levels in the studied aquatic system. Toxic equivalent (TEQ) values of PHCZs were determined on the basis of their relative effect potencies (REP) compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The median TEQ was 1.2 pg TEQ/g dry weight in sediment and 4.8–19.5 pg TEQ/g lipid weight in biological tissues. Our study demonstrated the broad exposure of PHCZs in San Francisco Bay and their characteristics of bioaccumulation and biomagnification along with dioxin-like effects. These findings raise the need for additional research to better elucidate their sources, environmental behavior, and fate in global environments.

From Storage to Retention: Expanding California's Options for Meeting Its Water Needs

California Roundtable on Water and Food Supply (CRWFS) | November 19th, 2012

Achieving a more effective and flexible water storage system requires a shift in the way that we, as a society, understand, define, and use storage as an element of integ

Achieving a more effective and flexible water storage system requires a shift in the way that we, as a society, understand, define, and use storage as an element of integrated water management. Broadening our view of what constitutes a storage reservoir must be accompanied by a shift in our policies and programs to support a “retention” approach to storage—one that holds as much water as possible in the landscape for later use, while maintaining healthy ecosystems. To be more resilient and better prepared for future variations in water supply, California must take advantage of all storage opportunities throughout the system that meet the goals of reliable water supply and ecosystem restoration. Several valuable aspects of water storage tend to be overlooked in terms of their ability to contribute to the availability and reliability of water supplies for uses that benefit society. In particular, California’s agricultural lands play an important role in the storage infrastructure. The value of working lands in helping to sequester water for later use while achieving many benefits, such as food security, flood management and habitat restoration, represents a critical missed opportunity for improving water security. Four key principles must guide efforts to ensure effective water retention in the future: 1. Storage integrates all hydrological components affecting water availability, movement, and retention to improve supply reliability statewide for evolving needs. 2. Comprehensive, timely, accurate, accessible, and transparent data and resulting information about our water resources is an essential foundation for effectively managing water storage in California. 3. An effective storage system requires the coordination of policies and regulations, activities, oversight, and accountability of all government agencies to meet local, regional, and statewide needs simultaneously. 4. Water storage and retention for improved water supply reliability and watershed health is facilitated by the availability of new sources of financial support that allow investment in quantified outcomes. Improving the flow of information through coordinated data management and institutional coordination can lead to powerful water retention outcomes. Several new and innovative funding mechanisms can complement traditional funding streams for water retention and are particularly well suited to agricultural applications.

From the extreme to the mean: Acceleration and tipping points of coastal inundation from sea level rise

American Geophysical Union (AGU) | December 18th, 2014

Relative sea level rise (RSLR) has driven large increases in annual water level exceedances (duration and frequency) above minor (nuisance level) coastal flooding elevat

Relative sea level rise (RSLR) has driven large increases in annual water level exceedances (duration and frequency) above minor (nuisance level) coastal flooding elevation thresholds established by the National Weather Service (NWS) at U.S. tide gauges over the last half-century. For threshold levels below 0.5 m above high tide, the rates of annual exceedances are accelerating along the U.S. East and Gulf Coasts, primarily from evolution of tidal water level distributions to higher elevations impinging on the flood threshold. These accelerations are quantified in terms of the local RSLR rate and tidal range through multiple regression analysis. Along the U.S. West Coast, annual exceedance rates are linearly increasing, complicated by sharp punctuations in RSLR anomalies during El Niño Southern Oscillation (ENSO) phases, and we account for annual exceedance variability along the U.S. West and East Coasts from ENSO forcing. Projections of annual exceedances above local NWS nuisance levels at U.S. tide gauges are estimated by shifting probability estimates of daily maximum water levels over a contemporary 5-year period following probabilistic RSLR projections of Koppet al.(2014) for representative concentration pathways(RCP) 2.6, 4.5, and 8.5. We suggest a tipping point for coastal inundation (30 days/per year with a threshold exceedance) based on the evolution of exceedance probabilities. Under forcing associated with the local-median projections of RSLR, the majority of locations surpass the tipping point over the next several decades regardless of specific RCP.

From the sanitary city to the sustainable city: challenges to institutionalising biogenic (nature’s services) infrastructure

Local Environment (Routledge) | January 4th, 2010

Much has been made of the need for cities to becomemore sustainable, particularly since for the first time in human history over half of the world’s population are urb

Much has been made of the need for cities to becomemore sustainable, particularly since for the first time in human history over half of the world’s population are urban dwellers. Cities concentrate human activities in an exceptionally powerful manner, and this includes resource use and the generation of pollution. Attention has turned towards cities for their capacity to enhance and use nature’s services – ecological sustainability – to remediate some of their own environmental impacts. Insufficient attention has been paid to the challenges of implementation of this new approach to infrastructure in an era of devolution and skepticism about government. This paper discusses these twin and interwoven questions through the lens of an on-going natural experiment, the implementation of a million tree-planting campaign in Los Angeles, CA.

From the Sierra to the Sea: The Ecological History of the San Francisco Bay-Delta Watershed

Bay Institute | July 15th, 2003

A vast watershed connects the mountain streams surrounding California’s Central Valley with San Francisco Bay and the ocean beyond. Over the course of the last two cent

A vast watershed connects the mountain streams surrounding California’s Central Valley with San Francisco Bay and the ocean beyond. Over the course of the last two centuries, much of the natural productivity, biodiversity and ecological integrity of the watershed has been destroyed by modifying the environment without fully understanding the long-term environmental consequences. Long the site of some of the nation’s most intensive conflicts over the use of land and water resources, this system is now emerging as the focus of one of the most ambitious ecological restoration efforts ever undertaken in the United States. This report was designed to provide a coherent and defensible ecological framework and information base for restoration. The need for such an historical, broad-scale perspective on system ecology stems from two fundamental principles of ecological restoration - the need to manage toward a natural template and to manage at ecosystem and landscape levels.