Storms, Floods, and the Science of Atmospheric Rivers

American Geophysical Union (AGU) | August 9th, 2011

Imagine a stream of water thousands of kilometers long and as wide as the distance between New York City and Washington, D. C., flowing toward you at 30 miles perhour.

Imagine a stream of water thousands of kilometers long and as wide as the distance between New York City and Washington, D. C., flowing toward you at 30 miles perhour. No, this is not some hypothetical physics problem—it is a real river, carrying more water than 7–15 Mississippi Rivers combined. But it is not on land. It’s a river of water vapor in the atmosphere.

Strategic Plan to Protect California Coast and Ocean 2020-2025

California Ocean Protection Council (COPC) | February 26th, 2020

Strategies for Managing the Colorado River in an Uncertain Future

Utah State University | January 11th, 2020

Colorado River managers and stakeholders face many uncertainties—issues such as climate change, future water demand, and evolving ecological priorities. Managers and st

Colorado River managers and stakeholders face many uncertainties—issues such as climate change, future water demand, and evolving ecological priorities. Managers and stakeholders are looking for new ways to communicate about uncertain future conditions, help cope with an uncertain future, and develop public policy when future conditions are highly uncertain. Historically, Colorado River managers have operated Lake Powell and Lake Mead under the assumption that the future natural flow regime of the Colorado River at Lee Ferry will resemble the previously observed regime, but most climate scientists believe that the flow regime is changing, and that future flows will be lower, more variable, and more uncertain.

Study role of climate change in extreme threats to water quality

Nature Portfolio (Springer Nature) | July 21st, 2016

With concerns about climate ‘extremes’ growing, water is often the focus — either too much or too little. That is no coincidence: climate and the hydrolog

With concerns about climate ‘extremes’ growing, water is often the focus — either too much or too little. That is no coincidence: climate and the hydrological cycle are tightly coupled, and water is essential to ecosystems and societies. But it is not just the quantity of water that matters. So does its quality.

Summarizing Relationships among Landfalling Atmospheric Rivers, Integrated Water Vapor Transport, and California Watershed Precipitation 1982–2019

American Meteorological Society (AMS) | September 16th, 2022

Atmospheric rivers (ARs) are defined as corridors of enhanced integrated water vapor transport (IVT) and produce large fractions of annual precipitation in regions with c

Atmospheric rivers (ARs) are defined as corridors of enhanced integrated water vapor transport (IVT) and produce large fractions of annual precipitation in regions with complex terrain along the western coastlines of midlatitude continents (e.g., 30%–50% along the U.S. West Coast in California). This study investigates this relationship among landfalling ARs, IVT, and watershed mean areal precipitation (MAP) for a 38-yr period over California. On average, the daily average IVT magnitude at different coastal locations explains ∼34% of the variance in annual watershed MAP across 140 Hydrologic Unit Code 8 (HUC-8) watersheds with large spatial variability across California. Further investigation of the IVT magnitude and direction at coastal locations illustrated that accounting for water vapor transport direction increases the explained variance in annual MAP to an average of 45%, with highest values (∼65%) occurring in watersheds over Northern and coastal California. Similar investigation of the lower-tropospheric water vapor flux vector at 850 and 925 hPa revealed further increases in the explained variance in annual MAP to an average of >50%. The results of this study 1) emphasize the importance of both IVT direction and water vapor flux altitude to watershed MAP, 2) align well with previous studies for select locations that highlight the importance of upslope (i.e., lower tropospheric) water vapor flux during landfalling ARs and precipitation, and 3) motivate the development of AR-related and watershed-centric forecast tools that incorporate IVT direction and water vapor flux altitude parameters in addition to IVT magnitude.

Summary of Climate Change Impacts to Water and Sanitation for Frontline Communities in the United States: Water, Sanitation, and Climate Change in the United States Part 1

Pacific Institute | December 6th, 2023

Climate change is among the most urgent, wide-ranging crises we face. It poses significant challenges and is already resulting in severe impacts to drinking water and san

Climate change is among the most urgent, wide-ranging crises we face. It poses significant challenges and is already resulting in severe impacts to drinking water and sanitation access—both for those currently living without access and for communities where forces like drought, flooding, sea-level rise, wildfires, and intensifying storms threaten to degrade or strip basic services from the people. Access to sufficient, safe, acceptable, physically accessible, and affordable water and sanitation is essential for human health and wellbeing, as well as economic prosperity—and climate change will inevitably make ensuring all have access more challenging. Without water and sanitation access, people do not have water to drink, cannot clean, shower, or wash their hands, and cannot safely dispose of human waste. They may have to travel long distances to purchase and haul water back to their homes. Without access to water, they also have less ability to cool their homes, protect themselves from wildfires, and work or go to school. An economic assessment by DigDeep found that for every household in the United States without access to water and sanitation, the domestic economy loses $15,800 annually in extra health care costs, time and money spent on bottled water, lost educational or work opportunities, and premature death (DigDeep 2022). (Click here for Part 2)

Sustainable floodplains through large-scale reconnection to rivers

American Association for the Advancement of Science (AAAS) | December 11th, 2009

Flooding is the most damaging natural disaster worldwide, and the flood-vulnerable population is expected to grow in coming decades. Flood risks will likely increase beca

Flooding is the most damaging natural disaster worldwide, and the flood-vulnerable population is expected to grow in coming decades. Flood risks will likely increase because of both climate change and shifting land uses, such as filling of wetlands and expansion of impervious surfaces, that lead to more rapid precipitation runoff into rivers. In the United States, annual river flood losses continue to rise, punctuated by major events in the Midwest (1993, $30 billion in total costs; 2008, $15 billion) and California's Central Valley (1995 and 1997; $4 billion each event). Meanwhile, pressure to develop new housing in floodprone areas near rivers (floodplains) continues , even as levee-system maintenance is chronically underfunded.

Sustainable L.A. Grand Challenge Environmental Report Card for Los Angeles County: Water 2019

University of California, Los Angeles (UCLA) | October 22nd, 2019

The Sustainable LA Grand Challenge (SLA GC) Environmental Report Card (ERC) for Los Angeles County (L.A. County) is the only comprehensive environmental report card for

The Sustainable LA Grand Challenge (SLA GC) Environmental Report Card (ERC) for Los Angeles County (L.A. County) is the only comprehensive environmental report card for a megacity in the world. This 2019 ERC on Water provides an in-depth look at the region’s efforts in moving toward a more resilient local water supply, which requires maximizing high quality local water supplies, improving water conveyance and treatment infrastructure, reducing water consumption, and implementing innovative technology and policy solutions. Twenty indicators were assessed across eight categories. Many of these indicators are new areas of assessment for the ERC and will provide a more comprehensive picture of current conditions compared to the 2015 ERC that last assessed L.A. County’s water. Grades were assigned in each category based on compliance with environmental laws or numeric standards where applicable, on our best professional judgment, and on historical improvements and context. This year’s grades range from D/ Incomplete to B+, and although there has been great progress in some areas, others still require significant improvement to raise the county’s C+ average.

Sustainable Management of a Water Reservoir System Facing Climate Uncertainty

Social Science Research Network (SSRN) | November 27th, 2024

Water scarcity is a growing global issue. It affects even highly developed regions like California, the world's fifth largest economy, where years of severe droughts inte

Water scarcity is a growing global issue. It affects even highly developed regions like California, the world's fifth largest economy, where years of severe droughts interspersed with unusually wet seasons have caused societal debates over the management of the water resources stored in the state's extensive reservoir system. This paper presents a strategic optimization model for the long-term, sustainable management of such a system. Introducing a new modeling paradigm based on cycles of stochastic length, defined by the event when all reservoirs are simultaneously full, we avoid the limitations of traditional models and obtain sustainable management policies. To address the unpredictable effect of climate change on future water supply, we adopt a distributionally robust framework where nature chooses adverse inflow distributions. This leads to a stochastic shortest path problem under distributional ambiguity. Using tools from stochastic dynamic programming and aggregation methods, we obtain policy insights and overcome the curse of dimensionality typically associated with systems models. In a case study for California's Sacramento River Basin, we report suboptimality gaps between 3% and 15%, with our sustainable management policy reducing average cycle shortage costs by 40% compared to the current policy, demonstrating the significant cost saving potential.

Sycamore Alluvial Woodland Planting Guide

San Francisco Estuary Institute (SFEI) | August 1st, 2018

This memo builds on recent field-based studies which examined the relative distribution, health, and regeneration patterns of two major stands of sycamore alluvial woodla

This memo builds on recent field-based studies which examined the relative distribution, health, and regeneration patterns of two major stands of sycamore alluvial woodland (SAW) in Santa Clara County. Given that the acquisition, restoration, and improved management of SAW is mandated as part of the Santa Clara Valley Habitat Plan (VHP), it is increasingly critical to understand how, when, and where sycamores establish, which is critical for successful restoration design and planting success. This memo is meant to summarize recent studies on habitat requirements of the SAW habitat type, and present a planting plan and monitoring framework for restoring SAW habitat at two sites in Santa Clara County. As the science and restoration of SAW is an ongoing topic of interest, we also suggest possible subsequent studies needed to further sycamore restoration goals.