Santa Clara Valley Water District

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Reports 1 - 10 of 1602

Proposed Policy to Plan for Sea Level Rise - "The Policy will serve as guidance in developing the more detailed Sea Level Rise Adaptation Plan to protect Palo Alto’s neighborhoods, economy, and Baylands habitat. . . . The Plan will be delivered for Council review by December 2020 and will serve as the Sea Level Rise Implementation Plan chapter of the 2020 S/CAP Update. The Plan will include suggested measures to protect infrastructure, determine sea level height triggers for the Plan's various actions, and initiate adaptation strategies. The adaptation strategies of the Plan will likely include measures such as revising building requirements, staff and public education, and integrating sea level rise policy elements into other City operational procedures and plans." (City of Palo Alto)
Publication Date: Mar 18, 2019
Topics: Adaptation / California: Bay Area and Delta / Land Use, environmental management systems, and regulation / Sea level rise /

Dynamic flood modeling essential to assess the coastal impacts of climate change - "Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant economic, humanitarian, and national-security challenges. However, the majority of previous efforts to characterize potential coastal impacts of climate change have focused primarily on long-term SLR with a static tide level, and have not comprehensively accounted for dynamic physical drivers such as tidal non-linearity, storms, short-term climate variability, erosion response and consequent flooding responses. Here we present a dynamic modeling approach that estimates climate-driven changes in flood-hazard exposure by integrating the effects of SLR, tides, waves, storms, and coastal change (i.e. beach erosion and cliff retreat). We show that for California, USA, the world's 5th largest economy, over $150 billion of property equating to more than 6% of the state’s GDP and 600,000 people could be impacted by dynamic flooding by 2100; a three-fold increase in exposed population than if only SLR and a static coastline are considered. The potential for underestimating societal exposure to coastal flooding is greater for smaller SLR scenarios, up to a seven-fold increase in exposed population and economic interests when considering storm conditions in addition to SLR. These results highlight the importance of including climate-change driven dynamic coastal processes and impacts in both short-term hazard mitigation and long-term adaptation planning." (Barnard, P. L., 2019, Scientific Reports)
Source: United States. Geological Survey
Publication Date: Mar 13, 2019
Topics: California: Statewide / Flooding / Sea level rise /

Climate variability and change of Mediterranean-type climates - "Mediterranean-type climates are defined by temperate, wet winters and hot or warm dry summers and exist at the western edges of five continents in locations determined by the geography of winter storm tracks and summer subtropical anticyclones. The climatology, variability and long term changes in winter precipitation in Mediterranean-type climates, and the mechanisms for model-projected near-term future change, are analyzed. Despite commonalities in terms of location in the context of planetary scale dynamics, the causes of variability are distinct across the regions. Internal atmospheric variability is the dominant source of winter precipitation variability in all Mediterranean-type climate regions, but only in the Mediterranean is this clearly related to annular mode variability. Ocean forcing of variability is a notable influence only for California and Chile. As a consequence, potential predictability of winter precipitation variability in the regions is low. In all regions, the trend in winter precipitation since 1901 is similar to that which arises as a response to changes in external forcing in the models participating in the Coupled Model Intercomparison Project Five. All Mediterranean-type climate regions, except in North America, have dried and the models project further drying over coming decades. In the northern hemisphere, dynamical processes are responsible: development of a winter ridge over the Mediterranean that suppresses precipitation and of a trough west of the North American west coast that shifts the Pacific stormtrack equatorward. In the southern hemisphere, mixed dynamic-thermodynamic changes are important that place a minimum in vertically integrated water vapor change at the coast and enhance zonal dry advection into Mediterranean-type climate regions inland." (Seager, R., 2019, Journal of Climate)
Publication Date: Mar 6, 2019
Topics: California: Statewide / Precipitation, Extreme Weather /

Jet stream dynamics, hydroclimate, and fire in California from 1600 CE to present - "North Pacific jet stream (NPJ) behavior strongly affects cool-season moisture delivery in California and is an important predictor of summer fire conditions. Reconstructions of the NPJ before modern fire suppression began in the early 20th century identify the relationships between NPJ characteristics and precipitation and fire extremes. After fire suppression, the relationship between the NPJ and precipitation extremes is unchanged, but the NPJ-fire extremes relationship breaks down. Simulations with high CO2 forcing show higher temperatures, reduced snowpack, and drier summers by 2070 to 2100 whether overall precipitation is enhanced or reduced, thereby overriding historical dynamic NPJ precursor conditions and increasing fire potential due to thermodynamic warming. Recent California fires during wet extremes may be early evidence of this change." (Wahl, E. R., et al., 2019, Proceedings of the National Academy of Sciences)
Publication Date: Mar 4, 2019
Topics: California: Statewide / Precipitation, Extreme Weather / Temperature / Water supply, changes in supply, snowpack / Wildfires /

Adaptation to Future Water Shortages in the United States Caused by Population Growth and Climate Change - "Population growth and climate change will combine to pose substantial challenges for water management in the United States. Projections of water supply and demand over the 21st century show that in the absence of further adaptation efforts, serious water shortages are likely in some regions. Continued improvements in water use efficiency are likely but will be insufficient to avoid future shortages. Some adaptation measures that have been effective in the past, most importantly large additions to reservoir storage, have little promise. Other major adaptations commonly used in the past, especially instream flow removals and groundwater mining, can substantially lower shortages but have serious external costs. If those costs are to be avoided, transfers from irrigated agriculture probably will be needed and could be substantial." (Brown, T. C., et al., 2019, Earth's Future)
Publication Date: Feb 28, 2019
Topics: Adaptation / Agriculture / Groundwater / Water supply, changes in supply, snowpack /

Societal decisions about climate mitigation will have dramatic impacts on eutrophication in the 21st century - "Excessive nitrogen runoff leads to degraded water quality, harming human and ecosystem health. We examine the impact of changes in land use and land management for six combinations of socioeconomic pathways and climate outcomes, and find that societal choices will substantially impact riverine total nitrogen loading (+54% to -7%) for the continental United States by the end of the century. Regional impacts will be even larger. Increased loading is possible for both high emission and low emission pathways, due to increased food and biofuel demand, respectively. Some pathways, however, suggest that limiting climate change and eutrophication can be achieved concurrently. Precipitation changes will further exacerbate loading, resulting in a net increase of 1 to 68%. . . . Societal and climate trends must therefore both be considered in designing strategies for managing inland and coastal water quality." (Sinha, E., et al., 2019, Nature Communications)
Publication Date: Feb 26, 2019
Topics: Water quality /

Towards operational predictions of the near-term climate - "Near-term climate predictions -- which operate on annual to decadal timescales -- offer benefits for climate adaptation and resilience, and are thus important for society. Although skillful near-term predictions are now possible, particularly when coupled models are initialized from the current climate state (most importantly from the ocean), several scientific challenges remain, including gaps in understanding and modelling the underlying physical mechanisms. This Perspective discusses how these challenges can be overcome, outlining concrete steps towards the provision of operational near-term climate predictions. Progress in this endeavour will bridge the gap between current seasonal forecasts and century-scale climate change projections, allowing a seamless climate service delivery chain to be established." (Kushnir, Y., et al., Nature Climate Change, 2019)
Publication Date: Jan 21, 2019
Topics: Adaptation / Models and Tools /

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 /

Natural Variability Has Slowed the Decline in Western U.S. Snowpack Since the 1980s - "Spring snowpack in the mountains of the western United States has not declined substantially since the 1980s, despite significant global and regional warming. Here we show that this apparent insensitivity of snowpack to warming is a result of changes in the atmospheric circulation over the western United States, which have reduced snowpack losses due to warming. Climate model simulations indicate that the observed circulation changes have been driven in part by a shift in Pacific sea surface temperatures that is attributable to natural variability, and not part of the simulated response to anthropogenic forcing. Removing the influence of natural variability reveals a robust anthropogenic decline in western U.S. snowpack since the 1980s, particularly during the early months of the accumulation season (October–November). These results suggest that the recent stability of western U.S. snowpack will be followed by a period of accelerated decline once the current mode of natural variability subsides." (Siler, N., 2018, Geophysical Research Letters)
Publication Date: Dec 17, 2018
Topics: Water supply, changes in supply, snowpack /

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 /


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