Santa Clara Valley Water District

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Reports 1 - 10 of 1594

Assessing California's Climate Policies -- An Overview - "Chapter 135 of 2017 (AB 398, E. Garcia) requires our office to annually report on the economic impacts and benefits of California’s statutory greenhouse gas (GHG) emission goals—statewide emissions to 1990 levels by 2020 and to 40 percent below 1990 levels by 2030. This report provides a conceptual overview of the potential economic effects of policies intended to help meet these goals -- both positive and negative -- as well as identifies some key issues for the Legislature to consider when designing and evaluating state climate policies. In a companion report, Assessing California's Climate Policies -- Transportation, we provide more detailed information and comments on the state’s major policies aimed at reducing emissions from the transportation sector."
Source: California. Legislative Analyst's Office
Publication Date: Dec 21, 2018
Topics: California: Statewide / Greenhouse gas (GHG) reduction, mitigation /

SGMA Climate Change Resources - "This dataset includes processed climate change datasets related to climatology, hydrology, and water operations. The climatological data provided are change factors for precipitation and reference evapotranspiration gridded over the entire State. The hydrological data provided are projected stream inflows for major streams in the Central Valley, and streamflow change factors for areas outside of the Central Valley and smaller ungaged watersheds within the Central Valley. The water operations data provided are Central Valley reservoir outflows, diversions, and State Water Project (SWP) and Central Valley Project (CVP) water deliveries and select streamflow data. Most of the Central Valley inflows and all of the water operations data were simulated using the CalSim II model and produced for all projections. . . . Data are provided for projected climate conditions centered around 2030 and 2070. The climate projections are provided for these two future climate periods, and include one scenario for 2030 and three scenarios for 2070: a 2030 central tendency, a 2070 central tendency, and two 2070 extreme scenarios (i.e., one drier with extreme warming and one wetter with moderate warming). The climate scenario development process represents a climate period analysis where historical interannual variability from January 1915 through December 2011 is preserved while the magnitude of events may be increased or decreased based on projected changes in precipitation and air temperature from general circulation models."
Source: California. Dept. of Water Resources
Publication Date: Dec 13, 2018
Topics: California: Statewide / Groundwater / Models and Tools / Water supply, changes in supply, snowpack / Water utilities guidance /

A New Method to Characterize Changes in the Seasonal Cycle of Snowpack - "In the western US, water stored as mountain snowpack comprises a large percentage of the total water needed to meet the region’s demands, and it is likely that as the planet continues to warm, mountain snowpack will decline. However, detecting such trends in the observational record is challenging because snowpack is highly variable in both space and time. Here, a method for characterizing mountain snowpack is developed, which is based on fitting observed annual cycles of SWE to a gamma distribution probability density function. A new method for spatially interpolating the distribution fitting parameters in order to create a gridded climatology of SWE is also presented. Analysis of these data show robust trends in the shape of the annual cycle of snowpack in the western US. Specifically, over the 1982–2017 water years, the annual cycle of snowpack is becoming more narrow and more gaussian. A narrowing of the annual cycle corresponds to a shrinking of the length of the winter season, primarily because snowpack melting is commencing earlier in the water year. As the annual cycle of snowpack at high elevations tends to be more skewed than at lower elevations, a more gaussian shape suggests that snowpack is becoming more characteristic of that at lower elevations. Although no robust downward trends in annual mean SWE are found, robust trends in the shape of the SWE annual cycle have implications for regional water resources." (Evan, A. T., 2018, Journal of Applied Meteorology and Climatology)
Publication Date: Dec 12, 2018
Topics: Water supply, changes in supply, snowpack /

Snowpack Change From 1982 to 2016 Over Conterminous United States - "Snow water equivalent (SWE) variability and its drivers over different regions remain uncertain due to lack of representativeness of point measurements and deficiencies of existing coarse-resolution SWE products. Here, for the first time, we quantify and understand the snowpack change from 1982 to 2016 over conterminous United States at 4-km pixels. Annual maximum SWE decreased significantly (p < 0.05) by 41% on average for 13% of snowy pixels over western United States. Snow season was shortened significantly by 34 days on average for 9% of snowy pixels over the United States, primarily caused by earlier ending and later arrival of the season over western and eastern United States, respectively. October–March mean temperature and accumulated precipitation largely explain the temporal variability of 1 April SWE over western United States, and considering temperature alone would exaggerate the warming effect on SWE decrease. In contrast, temperature plays the primary role in the 1 April SWE variability over eastern United States." (Zeng, X., et al., 2018, Geophysical Research Letters)
Publication Date: Dec 12, 2018
Topics: Water supply, changes in supply, snowpack /

Marin County Sea Level Rise Publications - Marin ocean coast sea level rise adaptation report and vulnerability assessment. "The Adaptation Report is not a plan, but rather an informational document compiling adaptation options proposed to date to set the foundation for continued planning in West Marin." "The C-SMART project team gathered information from technical advisors, utility managers, and coastal residents about potential sea level rise impacts. The resulting Marin Ocean Coast Vulnerability Assessment summarizes the expected timing and extent of impacts, laying a foundation of knowledge to guide adaptation planning."
Publication Date: Dec 11, 2018
Topics: Adaptation / California: Bay Area and Delta / Sea level rise /

Explaining Extreme Events from a Climate Perspective - Annual special report from the Bulletin of the American Meteorological Society that "presents assessments of how human-caused climate change may have affected the strength and likelihood of individual extreme events."
Publication Date: Dec 10, 2018
Topics: Drought / Precipitation, Extreme Weather / Sea level rise / Temperature / Water supply, changes in supply, snowpack / Wildfires /

Fourth National Climate Assessment: Volume II: Impacts, Risks, and Adaptation in the United States - "This report, Volume II, draws on the foundational science described in Volume I, the Climate Science Special Report (CSSR). Volume II focuses on the human welfare, societal, and environmental elements of climate change and variability for 10 regions and 18 national topics [including water], with particular attention paid to observed and projected risks, impacts, consideration of risk reduction, and implications under different mitigation pathways. Where possible, NCA4 Volume II provides examples of actions underway in communities across the United States to reduce the risks associated with climate change, increase resilience, and improve livelihoods. This assessment was written to help inform decision-makers, utility and natural resource managers, public health officials, emergency planners, and other stakeholders by providing a thorough examination of the effects of climate change on the United States."
Source: United States. Global Change Research Program
Publication Date: Nov 23, 2018
Topics: Adaptation / Agriculture / Ecosystems, Habitat, Threatened Species / Energy management and conservation / Global issues, human impacts / Sea level rise / Water quality / Water supply, changes in supply, snowpack /

The Changing Character of the California Sierra Nevada as a Natural Reservoir - "The mountains of the Western United States provide a vital natural service through the storage and release of mountain snowpack, lessening impacts of seasonal aridity and satiating summer water demand. However, climate change continues to undermine these important processes. To understand how snowpack may change in the headwaters of California's major reservoirs, the North American Coordinated Regional Climate Downscaling Experiment is analyzed to assess peak water volume, peak timing, accumulation rate, melt rate, and snow season length across both latitudinal and elevational gradients. Under a high-emissions scenario, end-of-century peak snowpack timing occurs 4 weeks earlier and peak water volume is 79.3% lower. The largest reductions are above Shasta, Oroville, and Folsom and between 0- and 2,000-m elevations. Regional climate model and global forcing data set choice is important in determining historical snowpack character, yet by end century all models show a significant and similar decline in mountain snowpack." (Rhoades, A. M., et al., 2018, Geophysical Research Letters)
Source: Lawrence Berkeley National Laboratory
Publication Date: Nov 20, 2018
Topics: California: Statewide / Water supply, changes in supply, snowpack /

Decomposing the cascade of uncertainty in risk assessments for urban flooding reflecting critical decision-making issues - "Climate change risk assessments traditionally follow an analytical structure in which climate information is linked to impact models, and subsequently to damage models and decision-making tools. This structure generates a wide cascade of uncertainties that accumulate with each analytical step, consequently resulting in a wide range of risk estimates. This cascade of uncertainties can suggest that climate change risk assessments are not very useful in the context of decision-making regarding climate adaptation. However, many of the uncertainties revealed in traditionally structured climate risk assessments are not equally relevant to specific decisions, and presenting wide cascades of uncertainties can mask key decision-making parameters. In this paper, we show how the cascade of uncertainty relevant to decision-making can be reduced by applying an uncertainty decomposition approach, which, in study design, initially identifies the uncertainty cascade elements of particular relevance to the focal decision-making context. We compare the full cascade of uncertainties that emerge in a traditional risk assessment based on linked climate scenarios, impact modeling, and damage cost assessment with the uncertainty cascade generated by a detailed assessment of urban flooding risks where the focus is on key uncertainties in decision-making on climate change adaptation." (Halsnaes, K. and P. S. Kaspersen, 2018, Climatic Change)
Publication Date: Nov 14, 2018
Topics: Flooding /

California's Water - Updated report on water issues. (Updated November 2018)
Source: Public Policy Institute of California
Publication Date: Nov 13, 2018
Topics: California: Statewide / Water supply, changes in supply, snowpack /


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