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2017 Flood System Status Report
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2017 Flood System Status Report
California Department of Water Resources (DWR) | August 10, 2017...
Summary
This report is intended to assist flood management planners and engineers in characterizing facilities within the State Plan of Flood Control (SPFC) and...
This report is intended to assist flood management planners and engineers in characterizing facilities within the State Plan of Flood Control (SPFC) and to inform the 2017 Central Valley Flood Protection Plan Update (2017 CVFPP Update). The 2017 FSSR provides a concise repository of the status of SPFC Facilities as noted in related DWR evaluation and inspection efforts, along with the efforts of our local and federal partners. The 2012 CVFPP laid the foundation necessary for compliance with the Central Valley Flood Protection Act of 2008 and a new approach to flood management in the Central Valley.

As a supporting and informational document to the 2017 CVFPP Update, the 2017 FSSR includes information about inspecting and evaluating SPFC facilities. It also details and quantifies major components of existing flood risk within the Sacramento and San Joaquin river watersheds, and the factors that influence flood risk in relation to the various flood control structures within the SPFC. Additionally, the 2017 FSSR informs and details the current conditions of levees and channels within the SPFC, and includes finalized project information from DWR’s Levee Evaluations Program. Through updating the status of SPFC facilities, the State of California can continue to make informed decisions related to flood risk management.

This document is a collaborative effort by DWR, local, and federal partners, signifying a step forward in gaining deeper understanding of the flood system’s current status and condition in the Central Valley.

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Advancing Hydro-Economic Optimization to Identify Vulnerabilities and Adaptation Opportunities in California’s Water System

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Advancing Hydro-Economic Optimization to Identify Vulnerabilities and Adaptation Opportunities in California’s Water System
California Natural Resources Agency | August 27, 2018...
Summary
Long-term shifts in the timing and magnitude of reservoir inflows will affect water supply reliability in California. Hydro-economic models can help explore climate...
Long-term shifts in the timing and magnitude of reservoir inflows will affect water supply reliability in California. Hydro-economic models can help explore climate change concerns by identifying system vulnerabilities and adaptation strategies for statewide water operations. This work contributes a new open-source limited foresight implementation of the CALVIN model, a hydro-economic model including roughly 90% of California’s urban and agricultural water demands. The model includes the ability to determine water allocations on an annual basis without knowledge of future availability, and to efficiently evaluate ensembles of streamflow projections representing a range of possible future climates. We then assess the vulnerability of the statewide system to changes in total annual runoff and the fraction of runoff occurring during winter, which primarily depends on temperature. Results are analyzed with a focus on adaptation strategies, aided by the economic representation of water demand in the model. These strategies include changes to reservoir operating policies, and conveyance and storage expansion. As water availability decreases, model results show quadratic increases in shortage cost, and corresponding increases in the marginal costs of adaptation strategies and environmental flow constraints. Reservoirs adapt to warmer climates by increasing average storage levels in winter and routing excess runoff to downstream reservoirs with available capacity. Both small and large changes to reservoir operations were observed compared to historical hydrology, showing that no single operating strategy achieves optimality for all reservoirs. Increasing the fraction of winter flow causes small increases in total shortage cost, indicating the ability to manage a changing hydrologic regime with adaptive reservoir operations. The results of this project improve estimates of the cost of climate change to California’s water system under a range of future conditions and highlight adaptation strategies that minimize costs of increased hydrologic variability.

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Agricultural Damages and Losses from ARkStorm Scenario Flooding in California

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Agricultural Damages and Losses from ARkStorm Scenario Flooding in California
American Society of Civil Engineers (ASCE) | November 17, 2016...
Summary
Scientists designed the ARkStorm scenario to challenge the preparedness of California communities for widespread flooding with a historical precedence and increased likelihood under...

Scientists designed the ARkStorm scenario to challenge the preparedness of California communities for widespread flooding with a historical precedence and increased likelihood under climate change. California is an important provider of vegetables, fruits, nuts, and other agricultural products to the nation. This study analyzes the agricultural damages and losses pertaining to annual crops, perennial crops, and livestock in California exposed to ARkStorm flooding. Statewide, flood damage is incurred on approximately 23% of annual crop acreage, 5% of perennial crop acreage, and 5% of livestock, e.g., dairy, feedlot, and poultry, acreage. The sum of field repair costs, forgone income, and product replacement costs span $3.7 and $7.1 billion (2009) for a range of inundation durations. Perennial crop loss estimates dominate, and the vulnerability of orchards and vineyards has likely increased with recent expansion. Crop reestablishment delays from levee repair and dewatering more than double annual crop losses in the delta islands, assuming the fragile system does not remain permanently flooded. The exposure of almost 200,000 dairy cows to ARkStorm flooding poses livestock evacuation challenges.

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Anthropogenic warming has increased drought risk in California

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Anthropogenic warming has increased drought risk in California
National Academy of Sciences | March 2, 2015...
Summary
California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo...

California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo precipitation, the highest annual temperature, and the most extreme drought indicators on record. The extremely warm and dry conditions have led to acute water shortages, ground- water overdraft, critically low streamflow, and enhanced wildfire risk. Analyzing historical climate observations from California, we find that precipitation deficits in California were more than twice as likely to yield drought years if they occurred when conditions were warm. We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with warm conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also warm. Further, a large ensemble of climate model realizations reveals that additional global warming over the next few decades is very likely to create ∼100% probability that any annual-scale dry period is also extremely warm. We therefore conclude that anthropogenic warming is increasing the probability of co-occurring warm–dry conditions like those that have created the acute human and ecosystem impacts associated with the “exceptional” 2012–2014 drought in California.

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Anticipating Environmental and Environmental-Health Implications of Extreme Storms: ARkStorm Scenario

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Anticipating Environmental and Environmental-Health Implications of Extreme Storms: ARkStorm Scenario
American Society of Civil Engineers (ASCE) | July 22, 2015...
Summary
The ARkStorm Scenario predicts that a prolonged winter storm event across California would cause extreme precipitation, flooding, winds, physical damages, and economic impacts....

The ARkStorm Scenario predicts that a prolonged winter storm event across California would cause extreme precipitation, flooding, winds, physical damages, and economic impacts. This study uses a literature review and geographic information system-based analysis of national and state databases to infer how and where ARkStorm could cause environmental damages, release contamination from diverse natural and anthropogenic sources, affect ecosystem and human health, and cause economic impacts from environmental-remediation, liability, and health care costs. Examples of plausible ARkStorm environmental and health concerns include complex mixtures of contaminants such as petroleum, mercury, asbestos, persistent organic pollutants, molds, and pathogens; adverse physical and contamination impacts on riverine and coastal marine ecosystems; and increased incidences of mold-related health concerns, some vector-borne diseases, and valley fever. Coastal cities, the San Francisco Bay area, the Sacramento-San Joaquin River Delta, parts of the Central Valley, and some mountainous areas would likely be most affected. This type of screening analysis, coupled with follow-up local assessments, can help stakeholders in California and disaster-prone areas elsewhere better plan for, mitigate, and respond to future environmental disasters.

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Assessing and communicating the impacts of climate change on the Southern California coast

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Assessing and communicating the impacts of climate change on the Southern California coast
California Natural Resources Agency | August 27, 2018...
Summary
Over the course of this and the next century, the combination of rising sea levels, severe storms, and coastal erosion will threaten the...
Over the course of this and the next century, the combination of rising sea levels, severe storms, and coastal erosion will threaten the sustainability of coastal communities, development, and ecosystems as we currently know them. To clearly identify coastal vulnerabilities and develop appropriate adaptation strategies for projected increased levels of coastal flooding and erosion, coastal managers need user-friendly planning tools based on the best available climate and coastal science. In anticipation of these climate change impacts, many communities are in the early stages of climate change adaptation planning but lack the scientific information and tools to adequately address the potential impacts. In collaboration with leading scientists worldwide, 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 and translate that information using sophisticated physical process models into planning-scale physical, ecological, and economic exposure, shoreline change, and impact assessments, all delivered in two simple, user-friendly, online tools. Our results show that by the end of the 21st century, over 250,000 residents and nearly $40 billion in building value across Southern California could be exposed to coastal flooding from storms, sea level rise, and coastal change. Results for the other major population center in California (the greater San Francisco Bay Area) are also available but not explicitly discussed in this report. Together, CoSMoS has now assessed the exposure of 95% of the 26 million coastal residents of the State (17 million in Southern California)

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Atmospheric rivers drive flood damages in the western United States

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Atmospheric rivers drive flood damages in the western United States
Science Advances, American Association for the Advancement of Science (AAAS) | December 4, 2019...
Summary
Atmospheric rivers (ARs) are extratropical storms that produce extreme precipitation on the west coasts of the world’s major landmasses. In the United States, ARs...
Atmospheric rivers (ARs) are extratropical storms that produce extreme precipitation on the west coasts of the world’s major landmasses. In the United States, ARs cause significant flooding, yet their economic impacts have not been quantified. Here, using 40 years of data from the National Flood Insurance Program, we show that ARs are the primary drivers of flood damages in the western United States. Using a recently developed AR scale, which varies from category 1 to 5, we find that flood damages increase exponentially with AR intensity and duration:

Each increase in category corresponds to a roughly 10-fold increase in damages. Category 4 and 5 ARs cause median damages in the tens and hundreds of millions of dollars, respectively. Rising population, increased development, and climate change are expected to worsen the risk of AR-driven flood damage in future decades.

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California against the sea

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California against the sea
Los Angeles Times | July 7, 2019...
Summary
THE CALIFORNIA COAST GREW AND PROSPERED during a remarkable moment in history when the sea was at its tamest. But the mighty Pacific,...
THE CALIFORNIA COAST GREW AND PROSPERED during a remarkable moment in history when the sea was at its tamest.

But the mighty Pacific, unbeknownst to all, was nearing its final years of a calm but unusual cycle that had lulled dreaming settlers into a false sense of endless summer.

Elsewhere, Miami has been drowning, Louisiana shrinking, North Carolina’s beaches disappearing like a time lapse with no ending. While other regions grappled with destructive waves and rising seas, the West Coast for decades was spared by a rare confluence of favorable winds and cooler water. This “sea level rise suppression,” as scientists call it, went largely undetected. Blinded from the consequences of a warming planet, Californians kept building right to the water’s edge.

But lines in the sand are meant to shift. In the last 100 years, the sea rose less than 9 inches in California. By the end of this century, the surge could be greater than 9 feet.

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Central Coast Summary Report – California’s Fourth Climate Change Assessment

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Central Coast Summary Report – California’s Fourth Climate Change Assessment
California Natural Resources Agency, California Energy Commission (CEC) | September 28, 2018...
Summary
The Central Coast Region is notable for its extensive natural ecosystems, many of which will be impacted by climate change. Hardwood forests, scrublands, and...
The Central Coast Region is notable for its extensive natural ecosystems, many of which will be impacted by climate change. Hardwood forests, scrublands, and herbaceous grasslands comprise most of its land cover, with significantly less intensive agriculture and small-to medium-sized cities in the region. There is a strong demand for development in rural areas and agriculture is being developed on lands formerly supporting grazing or natural vegetation. The region continues to reflect an economic and social disconnect between prosperous coastal communities and agricultural areas with many low-income farm workers, inequalities that may result in disadvantaged groups suffering disproportionately from the impacts of climate change.

The counties included in this report are Santa Barbara, San Luis Obispo, Monterey, San Benito, and Santa Cruz, with some information for the northern part of Ventura County.

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Central Valley Flood Protection Plan Update 2017
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Central Valley Flood Protection Plan Update 2017
California Department of Water Resources (DWR) | August 29, 2017...
Summary
The Central Valley Flood Protection Plan (CVFPP) has guided the State’s participation in managing flood risk in areas protected by the State Plan...
The Central Valley Flood Protection Plan (CVFPP) has guided the State’s participation in managing flood risk in areas protected by the State Plan of Flood Control (SPFC) since the plan’s adoption pursuant to the Central Valley Flood Protection Act of 2008 in 2012. A strategic, long-range plan, the CVFPP and its updates describe a programmatic vision for flood system improvements over time in accordance with the requirements of the 2008 Act.

The CVFPP was prepared by the Department of Water Resources (DWR) and adopted by Central Valley Flood Protection Board (CVFPB) through Resolution 2012-25. As conceived by the legislature, the CVFPP is updated every 5 years, beginning in 2017.

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