Flood Management – California Water Library

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Primary Production in the Delta: Then and Now

University of California, Davis (UC Davis) | October 3rd, 2016

Summary

To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function

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Productive wetlands restored for carbon sequestration quickly become net CO2 sinks with site-level factors driving uptake variability

PLOS | March 25th, 2021

Summary

Inundated wetlands can potentially sequester substantial amounts of soil carbon (C) over the long-term because of slow decomposition and high primary productivity, partic

Inundated wetlands can potentially sequester substantial amounts of soil carbon (C) over the long-term because of slow decomposition and high primary productivity, particularly in climates with long growing seasons. Restoring such wetlands may provide one of several effective negative emission technologies to remove atmospheric CO2 and mitigate climate change. However, there remains considerable uncertainty whether these heterogeneous ecotones are consistent net C sinks and to what degree restoration and management methods affect C sequestration. Since wetland C dynamics are largely driven by climate, it is difficult to draw comparisons across regions. With many restored wetlands having different functional outcomes, we need to better understand the importance of site-specific conditions and how they change over time. We report on 21 site-years of C fluxes using eddy covariance measurements from five restored fresh to brackish wetlands in a Mediterranean climate. The wetlands ranged from 3 to 23 years after restoration and showed that several factors related to restoration methods and site conditions altered the magnitude of C sequestration by affecting vegetation cover and structure. Vegetation established within two years of re-flooding but followed different trajectories depending on design aspects, such as bathymetry-determined water levels, planting methods, and soil nutrients. A minimum of 55% vegetation cover was needed to become a net C sink, which most wetlands achieved once vegetation was established. Established wetlands had a high C sequestration efficiency (i.e. the ratio of net to gross ecosystem productivity) comparable to upland ecosystems but varied between years undergoing boom-bust growth cycles and C uptake strength was susceptible to disturbance events. We highlight the large C sequestration potential of productive inundated marshes, aided by restoration design and management targeted to maximise vegetation extent and minimise disturbance. These findings have important implications for wetland restoration, policy, and management practitioners.

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Projected 21st Century Coastal Flooding in the Southern California Bight. Part 1: Development of the Third Generation CoSMoSModel

Journal of Marine Science and Engineering (MDPI) | May 24th, 2018

Summary

Due to the effects of climate change over the course of the next century, the combination of rising sea levels, severe storms, and coastal change will threaten the susta

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Projected 21st Century Coastal Flooding in the Southern California Bight. Part 2: Tools for Assessing Climate Change-Driven Coastal Hazards and Socio-Economic Impacts

Journal of Marine Science and Engineering (MDPI) | July 2nd, 2018

Summary

This paper is the second of two that describes the Coastal Storm Modeling System (CoSMoS) approach for quantifying physical hazards and socio-economic hazard exposure in

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Projected Changes in California’s Precipitation Intensity-Duration-Frequency Curves

California Public Utilities Commission (CPUC) | August 15th, 2018

Summary

Traditionally, infrastructure design and rainfall-triggered landslide models rely on the notion of stationarity, which assumes that the statistics of hydroclimati

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Projected Changes in Precipitation, Temperature, and Drought across California’s Hydrologic Regions in the 21st Century

Climate (MDPI) | April 23rd, 2018

Summary

This study investigated potential changes in future precipitation, temperature, and drought across 10 hydrologic regions in California. The latest climate model projectio

This study investigated potential changes in future precipitation, temperature, and drought across 10 hydrologic regions in California. The latest climate model projections on these variables through 2099 representing the current state of the climate science were applied for this purpose. Changes were explored in terms of differences from a historical baseline as well as the changing trend. The results indicate that warming is expected across all regions in all temperature projections, particularly in late-century. There is no such consensus on precipitation, with projections mostly ranging from −25% to +50% different from the historical baseline. There is no statistically significant increasing or decreasing trend in historical precipitation and in the majority of the projections on precipitation. However, on average, precipitation is expected to increase slightly for most regions. The increases in late-century are expected to be more pronounced than the increases in mid-century. The study also shows that warming in summer and fall is more significant than warming in winter and spring. The study further illustrates that, compared to wet regions, dry regions are projected to become more arid. The inland eastern regions are expecting higher increases in temperature than other regions. Particularly, the coolest region, North Lahontan, tends to have the highest increases in both minimum and maximum temperature and a significant amount of increase in wet season precipitation, indicative of increasing flood risks in this region. Overall, these findings are meaningful from both scientific and practical perspectives. From a scientific perspective, these findings provide useful information that can be utilized to improve the current flood and water supply forecasting models or develop new predictive models. From a practical perspective, these findings can help decision-makers in making different adaptive strategies for different regions to address adverse impacts posed by those potential changes.

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Projected increases and shifts in rain-on-snow flood risk over western North America

Nature Portfolio (Springer Nature) | August 6th, 2018

Summary

Destructive and costly flooding can occur when warm storm systems deposit substantial rain on extensive snowcover, as observed in February 2017 with the Oroville

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Promoting atmospheric-river and snowmelt fueled biogeomorphic processes by restoring river-floodplain connectivity in California’s Central Valley

Springer | April 30th, 2015

Summary

Potential biogeomorphic benefits from intentional levee breaks and weir overflow on the managed floodplain-river system of California’s Sacramento and San Joaquin River

Potential biogeomorphic benefits from intentional levee breaks and weir overflow on the managed floodplain-river system of California’s Sacramento and San Joaquin River watershed (Central Valley) are discussed here. Prior to the nineteenth century, the system was characterized by natural levees alongside complex multichanneled rivers and tributaries, and geomorphic processes such as channel migration and avulsion, typical in lowland floodplain-river systems globally, dominated. Today, the floodplain-river system has been heavily modified with infrastructure such as levee embankments that disconnect floodplains from channels and diminish key processes of floodplain-river ecology. Unintentional levee breaks in river systems where floodplains have been developed for agriculture or urban uses still occur regularly (in a quarter of twentieth century years) and are sometimes catastrophic. Floodplain inundation, erosion, and sedimentation, the dominant geomorphic processes that occur during unintentional levee breaks, are flood risks in such embanked river systems. Climate and flood variability still dictate the frequency of unintentional levee breaks despite many decades of engineering. Of particular consequence are the so-called atmospheric-river (AR) storms. Since 1951, 81 % of breaks have occurred as a result of AR storms and flooding, while most of the rest occurred during snowmelt floods. Intentional levee breaks or planned weir overflows that are designed for floodplain restoration can facilitate a return towards more natural and dynamic biogeomorphic processes. In areas where room for flood-driven geomorphic processes is available on floodplains, local sediment scour and deposition near a levee break promote topographic diversity that enhances vegetation establishment and floodplain habitat. This chapter summarizes our current understanding of climate processes and flood variability that govern unintentional levee breaks or weir overflow. We also review examples of alternative flood management approaches in the Central Valley that promote processes necessary to restore or sustain lowland floodplain biogeomorphology. Future climate-driven changes in flood regime, such as enhanced flooding during winter months or more frequent atmospheric rivers, could be accommodated by additional intentional levee breaks or planned weir overflow for restoration. Implementation of these alternatives could be used to improve restoration policy and management of floods in embanked river floodplains.

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Property Prices in Peril

First Street | February 3rd, 2025

Summary

Regional desirability is being reshaped by chronic changes in climate across the country: coastal areas are increasingly threatened by sea level rise, while inland region

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Protocol for Closure of Delta Waterways

Office of Emergency Services | November 21st, 1997

Summary

This protocol describes the process for placing restrictions on vessel traffic on the San Joaquin/Sacramento Delta waterways during periods of high water levels and flood

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Page : 32

Primary Production in the Delta: Then and Now

Productive wetlands restored for carbon sequestration quickly become net CO2 sinks with site-level factors driving uptake variability

Projected 21st Century Coastal Flooding in the Southern California Bight. Part 1: Development of the Third Generation CoSMoSModel

Projected 21st Century Coastal Flooding in the Southern California Bight. Part 2: Tools for Assessing Climate Change-Driven Coastal Hazards and Socio-Economic Impacts

Projected Changes in California’s Precipitation Intensity-Duration-Frequency Curves

Projected Changes in Precipitation, Temperature, and Drought across California’s Hydrologic Regions in the 21st Century

Projected increases and shifts in rain-on-snow flood risk over western North America

Promoting atmospheric-river and snowmelt fueled biogeomorphic processes by restoring river-floodplain connectivity in California’s Central Valley

Property Prices in Peril

Protocol for Closure of Delta Waterways

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