Snow Level Characteristics and Impacts of a Spring Typhoon-Originating Atmospheric River in the Sierra Nevada, USA

Atmosphere (MDPI) | June 15th, 2018

On 5–7 April 2018, a landfalling atmospheric river resulted in widespread heavy precipitation in the Sierra Nevada of California and Nevada. Observed snow levels during

On 5–7 April 2018, a landfalling atmospheric river resulted in widespread heavy precipitation in the Sierra Nevada of California and Nevada. Observed snow levels during this event were among the highest snow levels recorded since observations began in 2002 and exceeded 2.75 km for 31 h in the northern Sierra Nevada and 3.75 km for 12 h in the southern Sierra Nevada. The anomalously high snow levels and over 80 mm of precipitation caused flooding, debris flows, and wet snow avalanches in the upper elevations of the Sierra Nevada. The origin of this atmospheric river was super typhoon Jelawat, whose moisture remnants were entrained and maintained by an extratropical cyclone in the northeast Pacific. This event was notable due to its April occurrence, as six other typhoon remnants that caused heavy precipitation with high snow levels (mean = 2.92 km) in the northern Sierra Nevada all occurred during October.

Socio-economic and ecological trade-offs of flood management

European Geosciences Union (EGU) | February 20th, 2019

In light of climate change and growing numbers of people inhabiting riverine floodplains, worldwide demand for flood protection is increasing, typically through engineeri

In light of climate change and growing numbers of people inhabiting riverine floodplains, worldwide demand for flood protection is increasing, typically through engineering approaches such as more and bigger levees. However, the well-documented “levee effect” of increased floodplain use following levee construction or enhancement often results in increased problems, especially when levees fail or are compromised by big flood events. Herein, we argue that there are also unintended socio-economic and ecological consequences of traditional engineering solutions that need to be better considered, communicated and weighed against alternative solutions. Socio-economic consequences include reduced aesthetic and recreational values as well as increased downstream flooding risk and reduced ecosystem services. Ecological consequences include hydraulic decoupling, loss of biodiversity and increased risk of contamination during flooding. In addition, beyond river losses of connectivity and natural riparian vegetation created by levees, changes in groundwater levels and increased greenhouse gas emissions are likely. Because flood protection requires huge financial investments and results in major and persistent changes to the landscape, more balanced decisions that involve all stakeholders and policymakers should be made in the future. This requires a transdisciplinary approach that considers alternative solutions such as green infrastructure and places emphasis on integrated flood management rather than on reliance on technical protection measures.

Sonoma Creek Baylands Strategy

Sonoma Land Trust | May 1st, 2020

The purpose of the Strategy is to provide Sonoma Land Trust and partners with a clear and comprehensive plan that coordinates the protection, acquisition, restoration, an

The purpose of the Strategy is to provide Sonoma Land Trust and partners with a clear and comprehensive plan that coordinates the protection, acquisition, restoration, and enhancement of diverse baylands habitats (e.g., subtidal, mudflat, tidal marsh, brackish marsh, freshwater marsh, upland-wetland transition), integrates natural processes to increase climate resilience of the Sonoma Creek Baylands, identifies appropriate public access, and provides recommendations for the redesign of SR 37 and increased connectivity under and across the SMART rail line where they pass through the Sonoma Creek Baylands. 

Spatial Dependence of Floods Shaped by Spatiotemporal Variations in Meteorological and Land‐Surface Processes

American Geophysical Union (AGU) | June 9th, 2020

Floods often affect large regions and cause adverse societal impacts. Regional flood hazard and risk assessments therefore require a realistic representation of spa

Floods often affect large regions and cause adverse societal impacts. Regional flood hazard and risk assessments therefore require a realistic representation of spatial flood dependencies to avoid the overestimation or underestimation of risk. However, it is not yet well understood how spatial flood dependence, that is, the degree of co‐occurrence of floods at different locations, varies in space and time and which processes influence the strength of this dependence. We identify regions in the United States with seasonally similar flood behavior and analyze processes governing spatial dependence. We find that spatial flood dependence varies regionally and seasonally and is generally strongest in winter and spring and weakest in summer and fall. Moreover, we find that land‐surface processes are crucial in shaping the spatiotemporal characteristics of flood events. We conclude that the regional and seasonal variations in spatial flood dependencies must be considered when conducting current and future flood risk assessments.

State Investments in Delta Levees: Key Issues For Updating Priorities

Delta Stewardship Council (Delta Council) | January 9th, 2015

This paper outlines 15 issues that will need to be considered as the Council updates the Delta Plan’s 36 provisions regarding State investment in the Delta’s levees.

This paper outlines 15 issues that will need to be considered as the Council updates the Delta Plan’s 36 provisions regarding State investment in the Delta’s levees. It summarizes background information 37 about these issues, provides references for further information, and highlights key points that will need 38 to be addressed over the coming months.

State of California Emergency Flood Fighting Methods

California Department of Water Resources (DWR) | August 1st, 2018

The ‘Flood Fighting Methods’ outlined in this booklet have proven effective during many years of use by DWR, United States Army Corps of Engineers, and local agencies

The ‘Flood Fighting Methods’ outlined in this booklet have proven effective during many years of use by DWR, United States Army Corps of Engineers, and local agencies on flood-related emergencies. This handbook is published by the DWR Flood Operations Branch and is designed to be used with the Flood Fighting Methods class.

State of California Sea Level Rise Guidance

California Natural Resources Agency (CNRA) | March 14th, 2018

The climate across California is changing, and the effects, such as rising average temperatures, shrinking mountain snowpack, more intense storms, and higher sea

The climate across California is changing, and the effects, such as rising average temperatures, shrinking mountain snowpack, more intense storms, and higher sea levels are expected to continue and worsen in the coming decades. Sea-level rise is caused by the thermal expansion of warming ocean water and melting of land ice as the Earth warms. It is one of the most obvious manifestations of the trend of climate change and is an immediate and real threat to lives, livelihoods, transportation, economies, and the environment in California. In April 2017, catalyzed by direction from Governor Brown and the need to ensure that best available science was informing sea-level rise planning decisions in California, a Working Group of the California Ocean Protection Council’s Science Advisory Team (OPC-SAT) released a report, entitled “Rising Seas in California: An Update on Sea-Level Rise.” The Rising Seas Report was prepared and peer-reviewed by some of the nation’s foremost experts in coastal processes, climate and sea-level rise science, observational and modeling science, the science of extremes, and decision-making under uncertainty. The report synthesized the current state of sea-level rise science, including advances in modeling and improved understanding of the processes that could drive extreme global sea-level rise as a result of ice loss from the Greenland and Antarctic ice sheets. The report found that: Scientific understanding of sea-level rise is advancing at a rapid pace. The direction of sea-level change is clear; sea levels are rising. The rate of ice loss from the Greenland and Antarctic ice sheets is increasing, and California is particularly vulnerable to sea-level rise caused by ice loss from West Antarctica. New scientific evidence has highlighted the potential for extreme sea-level rise. Probabilities of specific sea-level increases can inform decisions. Current policy decisions are shaping our coastal future. Waiting for scientific certainty is neither a safe nor prudent option. The increased understanding of sea-level rise projections and polar ice sheet loss warranted an update to the State’s sea-level rise guidance document to ensure decisions were based on the best available science. Additionally, an increased policy focus requiring state and local governments to incorporate climate change into decision making merited an update to address the needs of both state and local audiences. This updated document, the “State of California Sea-Level Rise Guidance” (Guidance), provides a bold, science-based methodology for state and local governments to analyze and assess the risks associated with sea-level rise, and to incorporate sea-level rise into their planning, permitting, and investment decisions. This Guidance provides: 1. A synthesis of the best available science on sea- level rise projections and rates for California; 2. A step-by-step approach for state agencies and local governments to evaluate those projections and related hazard information in decision making; and 3. Preferred coastal adaptation approaches.

State of the Estuary, October 2013

San Francisco Estuary Partnership (SFEP) | October 31st, 2013

State Plan of Flood Control Descriptive Document (2010)

California Department of Water Resources (DWR) | January 15th, 2010

This report provides an inventory and description of the existing flood control works (facilities), lands, programs, plans, conditions, and mode of operations and mainten

This report provides an inventory and description of the existing flood control works (facilities), lands, programs, plans, conditions, and mode of operations and maintenance (O&M) for the State-Federal flood protection system in the Central Valley of California. This flood protection system is composed of federally authorized project levees and related facilities for which the State has provided assurances1 of cooperation to the federal government. These State-provided assurances are an important distinction for what constitutes the State-federal flood protection system since other flood protection facilities in the Central Valley are not covered by State assurances and are not part of the State-federal system. Collectively, the facilities, lands, programs, conditions, and mode of O&M for the State-Federal flood protection system in the Central Valley are referred to as the State Plan of Flood Control (SPFC). This SPFC Descriptive Document is the first time that an inventory of the SPFC has been compiled or referenced in a single document. Until now, much of the information on the SPFC has been individually maintained for each of the many flood protection projects that constitute State-federal flood protection along the Sacramento and San Joaquin rivers and tributaries. For example, much of the information contained in sections of this report originates in 118 individual project (unit-specific) O&M manuals. The O&M manuals provide key information about each project and how it should be operated and maintained (see reference digital versatile disc (DVD) at the back of this report). In addition, since the individual projects for the system were implemented over almost a century, some information may have been lost or never obtained. In those cases, gaps exist in the information presented in this report and further research is required. It is important to note that the SPFC is only a portion of the larger system that provides flood protection for the Central Valley. The SPFC relies on many other features that do not meet the definition of the SPFC. For example, non-SPFC reservoirs provide substantial regulation of flows to levels that SPFC facilities can mostly handle. Private levees, locally operated drainage systems, and other facilities work in conjunction with SPFC facilities. Management practices such as emergency response, floodplain management, and other practices are part of the overall flood protection system. All parts of the system, including the SPFC, depend on other parts of the system to operate as a unit. This report is structured as a reference document for the SPFC. It includes narrative descriptions, tables, and figures, especially maps, to help the reader find information for this complex flood management system. Some sections include summary sections for readers who only need an overview of the subject. RELATED DOCUMENT: State Plan of Flood Control Descriptive Document 2016 Update

State Plan of Flood Control Descriptive Document 2016 Update

California Department of Water Resources (DWR) | December 14th, 2016

The November 2016 State Plan of Flood Control (SPFC) Descriptive Document Update (2016 Update) is intended to serve as a reference for flood management planners and opera

The November 2016 State Plan of Flood Control (SPFC) Descriptive Document Update (2016 Update) is intended to serve as a reference for flood management planners and operators at the local, State, and federal levels. It is not a stand-alone document; rather, it works in conjunction with the November 2010 SPFC Descriptive Document, builds upon information presented in the original report, and documents changes to the SPFC that have occurred between November 2010 and July 2016. The 2016 Update documents the inventory of flood control projects and works (facilities), lands, programs, plans, conditions, and mode of operations and maintenance for the State-federal flood management system in the Sacramento River and San Joaquin River watersheds of California, as well as informs the 2017 Central Valley Flood Protection Plan Update. In 2006 and 2007, California voters approved the Disaster Preparedness and Flood Prevention Bond Act of 2006 and the Central Valley Flood Protection Act of 2008 respectively. These acts defined the Sacramento River and San Joaquin River federal-State flood control projects as the SPFC, and required DWR to develop, and the Central Valley Flood Protection Board to adopt, a Central Valley Flood Protection Plan. The Central Valley Flood Protection Plan is broader than the SPFC, affecting the entire watersheds of the Sacramento and San Joaquin valleys. A complex system of dams and reservoirs, levees, weirs, bypasses, and other features constructed piecemeal over the last 100 years protects urban and rural areas against most flooding. This system has prevented billions of dollars in damage in its lifetime. A portion of this complex flood protection system includes State and federally authorized projects for which the Central Valley Flood Protection Board or DWR has provided assurances of cooperation to the federal government, known as the SPFC. These statutory authorizations include provisions regarding responsibility for operation and maintenance of the flood control facilities. The California Legislature has authorized funding for numerous flood control projects throughout the Sacramento and San Joaquin River watersheds. As the SPFC evolves, updates to the SPFC Descriptive Document will be useful in determining funding eligibility for funding for facility improvements. RELATED DOCUMENT:  State Plan of Flood Control (2010)