US drinking water quality: exposure risk profiles for seven legacy and emerging contaminants

Nature Portfolio (Springer Nature) | September 23rd, 2023

Using Graywater and Stormwater to Enhance Local Water Supplies: An Assessment of Risks, Costs, and Benefits

National Academy of Sciences (NAS) | December 1st, 2016

Much of the United States faces chronic or episodic water shortages. It is the topic of daily news in the West, where a historic 4-year drought has caused California to

Much of the United States faces chronic or episodic water shortages. It is the topic of daily news in the West, where a historic 4-year drought has caused California to restrict the delivery of water to cities and farms. At the same time, the Midwest and Northeast have received drenching rains and heavier than normal snow. Against this backdrop—of not enough water or too much water—the National Academies of Sciences, Engineering, and Medicine’s Water Science and Technology Board initiated a study on the beneficial use of stormwater and graywater. Graywater is a year-round source of water for nonpotable use, and use of urban stormwater can augment local water supplies, reduce demand for imported water, and lessen impacts from discharge.

Using Landsat and MODIS satellite collections to examine extent, timing, and potential impacts of surface water inundation in California croplands

Remote Sensing Applications: Society and Environment (RSASE) | October 1st, 2022

The state of California, United States of America produces many crop products that are both utilized domestically and exported throughout the world. With nearly 39,000 km

The state of California, United States of America produces many crop products that are both utilized domestically and exported throughout the world. With nearly 39,000 km2 of croplands, monitoring unintentional and intentional surface water inundation is important for water resource management and flood hazard readiness. We examine inundation dynamics in California croplands from 2003 to 2020 by intersecting monthly surface water maps (n = 216 months) derived using two satellite remote sensing platforms (Landsat and Moderate Resolution Imaging Spectroradiometer [MODIS]) with a high-quality cropland map generated by the California Department of Water Resources. Surface water maps were produced using the Dynamic Surface Water Extent model, in which satellite image pixels are classified into different levels of detection confidence. Our analysis focused on calculating monthly and annual occurrence of “high confidence” water for each satellite collection across eight cropland types and 58 counties. Results indicate that 49.9% (MODIS) to 56.4% (Landsat) of croplands were inundated at least once during the 18-year timespan. Rice crops, due to their unique need of consistent surface water and dominance as a crop type in CA, had the highest proportion of and mean annual inundation area, while citrus crops had the lowest. Mean monthly inundation patterns in most croplands followed California's precipitation patterns with high inundation during the winter and spring rainy season. At the county level, croplands in the southern Central Valley typically had high occurrences of inundation in conjunction with large crop areas. Exposure and sensitivity of inundation for three crop types (citrus, deciduous, and vineyards) that are typically less associated with intentional inundation were geographically variable, but overall were generally highest in counties in the southern Central Valley, California's primary agricultural region. Flood and precipitation related crop insurance claims indicated that rice had the highest mean indemnity payout for any month with damages typically occurring in March and April. Insurance claims were also high in deciduous fruit and nut crops, which had peak damages in February. A comparison between inundation results and insurance claims suggests that the inundation mapped by our process coincides with claim activity. These data elucidate water inundation patterns across the state that can serve to inform farmers, insurers, decision makers, resource managers, and flood mitigation professionals.

Variable vertical land motion and its impacts on sea level rise projections

American Association for the Advancement of Science (AAAS) | January 29th, 2025

Coastal vertical land motion (VLM), including uplift and subsidence, can greatly alter relative sea level projections and flood mitigations plans. Yet, current projection

Coastal vertical land motion (VLM), including uplift and subsidence, can greatly alter relative sea level projections and flood mitigations plans. Yet, current projection frameworks, such as the IPCC Sixth Assessment Report, often underestimate VLM by relying on regional linear estimates. Using high-resolution (90-meter) satellite data from 2015 to 2023, we provide local VLM estimates for California and assess their contribution to sea level rise both now and in future. Our findings reveal that regional estimates substantially understate sea level rise in parts of San Francisco and Los Angeles, projecting more than double the expected rise by 2050. Additionally, temporally variable (nonlinear) VLM, driven by factors such as hydrocarbon and groundwater extraction, can increase uncertainties in 2050 projections by up to 0.4 meters in certain areas of Los Angeles and San Diego. This study highlights the critical need to include local VLM and its uncertainties in sea level rise assessments to improve coastal management and ensure effective adaptation efforts.

Vulnerability Assessments in Support of the Climate Ready Estuaries Program: A Novel Approach Using Expert Judgment, Volume I

U.S. Environmental Protection Agency (EPA) | January 1st, 2012

The San Francisco Bay estuary is highly vulnerable to climate - related changes including increased water temperatures, changes in precipitation and winds, and sea leve

The San Francisco Bay estuary is highly vulnerable to climate - related changes including increased water temperatures, changes in precipitation and winds, and sea level rise. Impacts such as increased inundation of coastal wetlands, changes in water availability and quality, and altered patterns of sedimentation and erosion are increasingly interacting with other human stressors such as extractive water uses and land use changes. Thus it is essential that estuary managers become ‘climate-ready’ by: assessing the vulnerability of natural resources to climate change; considering strategic choices among adaptation strategies in the near term; and engaging in longer term planning based on a range of plausible scenarios of future change. In an era of shrinking budgets coupled with increasingly complex decision-making needs—often taking place in a context of uncertainty and incomplete information— managing natural resources in the face of climate change will be challenging. There is a need for assessment methods that take advantage of existing scientific expertise to help identify robust adaptation strategies, weigh difficult trade-offs, and justify strong action, all in a timely and efficient manner. The purpose of this project was to carry out a pilot vulnerability assessment for the San Francisco Estuary Partnership’s (SFEP) natural resources using expert judgment, the results of which could be linked to adaptation planning. To this aim, EPA’s Office of Research and Development collaborated with SFEP and the San Francisco Bay Conservation and Development Commission on a novel expert elicitation exercise for ‘rapid’ vulnerability assessment. A trial exercise was carried out during a two-day workshop in which two groups of seven experts each focused on two key ecosystem processes: sediment retention in salt marshes and community interactions of shorebirds with their predators and prey (see Figure ES - 1). The exercise, which was based on formal expert elicitation techniques but tailored specifically for qualitative analysis of ecosystem processes, was designed to glean expert information on the sensitivities of ecosystem process components under future climate scenarios . This was followed by group discussions of the implications of the results for management in light of climate change, as well as feedback on the exercise itself.  

Water is a master variable: Solving for resilience in the modern era

Water Security, Elsevier | November 21st, 2019

Resilience is increasingly recognized as an imperative for any prospect of sustainable development, as it relates to our ability to sustain human well-being and progress

Resilience is increasingly recognized as an imperative for any prospect of sustainable development, as it relates to our ability to sustain human well-being and progress under the planetary and societal changes that we face now and into the future. Yet, we are ill-prepared to meet this challenge. We neither fully understand nor manage consistently for resilience of the human and natural systems that we must steward through extraordinary change. A unifying approach and common currency would help us to understand and manage for resilience under uncertain futures. Water is an essential, defining element in human and natural systems. Human civilization and water systems have co-evolved as a coupled system, with the majority of natural freshwater systems transformed to meet our demands. Shifting patters of water availability in space and time will define key pathways and tipping points for our resilience, and thus requirements for water system resilience must guide the trajectories and boundaries of human development. Here, we consider the thesis that water offers a key to unlocking the complex challenge of designing and managing for the resilience of coupled human-natural systems. We examine what constitutes a resilient system, what drives freshwater resilience, and how pathways to human resilience may be charted and navigated through the medium of water. Our theoretical treatise frames a portfolio of research that tests this thesis, including modeling and applications to water and water-dependent systems.

Water Supply Damage, Recovery, and Lifeline Interaction in an Earthquake Sequence

American Society of Civil Engineers (ASCE) | September 7th, 2017

Earthquake damage to water supply systems profoundly affects society, potentially costing the economy tens of billions of dollars. Water agencies for 22% of the U.S. popu

Earthquake damage to water supply systems profoundly affects society, potentially costing the economy tens of billions of dollars. Water agencies for 22% of the U.S. population face high seismic risks. Computer models can help operators manage that risk. In recent research, the University of Colorado (CU) developed a stochastic model of water-supply pipeline damage and restoration. It offers some new capabilities: time-varying repair resources, multiple earthquake perils, lifeline interaction, avoiding hydraulic analysis, and no black-box software. CU exercised the model for the East Bay Municipal Utility District (EBMUD) and the San Jose Water Company, considering a hypothetical large Hayward Fault earthquake. EBMUD staff peer reviewed the methodology and results and find them credible and consistent with past earthquakes. EBMUD is using the results as part of its resilience program. Possible uses include prioritizing additional hardening or redundancy, identifying repair priorities, estimating resource needs, and informing earthquake exercises.

Water, Sanitation, and Climate Change in the United States Series, Part 2

Pacific Institute | October 15th, 2024

In the United States, federal, tribal, state, and local laws and policies exist to govern the provision of water and sanitation services to communities and homes. The law

In the United States, federal, tribal, state, and local laws and policies exist to govern the provision of water and sanitation services to communities and homes. The laws are designed to ensure the protection of public health and the environment; deliver sufficient, safe water for drinking, bathing, cooking, and other household needs; and remove and treat domestic (i.e., household) waste. People without complete plumbing or safe water live within the “water access gap.” As explored in the first report in this series, climate change—from extreme temperatures to droughts, floods, extreme storms, and wildfires—is making it hard to close this gap and keep it from growing. Water and sanitation systems in frontline communities already feel the disproportionate “first and worst” impacts of climate change to these systems and to their access to water and sanitation. Laws and policies should help anticipate and plan  or the incremental and catastrophic impacts of climate change and protect those most harmed by the effects. Unfortunately, in most cases, the climate is changing faster than the law can respond, thereby leaving frontline communities’ water and sanitation systems vulnerable to damage or destruction. This is part two in the three-part Water, Sanitation, and Climate Change in the United States series. Click here for part one and here for part three.

Why People Adopt Climate Change Adaptation and Disaster Risk Reduction Behaviors: Integrated Model of Risk Communication and Results from Hurricanes, Floods, and Wildfires

American Meteorological Society (AMS) | November 1st, 2022

With climate change, weather and climate disaster risks are increasing. At-risk individuals can take climate adaptation and disaster risk reduction behaviors to mitigate

With climate change, weather and climate disaster risks are increasing. At-risk individuals can take climate adaptation and disaster risk reduction behaviors to mitigate and prepare for disaster risks, reduce costs from damage, and save their lives. However, previous fragmented studies have not provided an integrated model to directly compare the factors and identify factors that are most influential in at-risk community members’ behaviors. I present the Integrated Model of Risk Communication by consolidating major theories. This study uses structural equation modeling of quantitative surveys to simultaneously test the impacts of 15 factors on 15 adaptation behaviors for the two most common federally declared disasters (wildfires and hurricanes with floods) in three disaster-prone U.S. states (California, Florida, and Texas) (N = 3,468). Specifically, this study examines 15 behaviors including preparedness, nonstructural mitigation, structural mitigation, insurance purchase, and adaptation policy support. Social norms perceptions, self-efficacy, response efficacy, and resource constraints strongly affect behaviors. Response efficacy strongly affects policy support. Risk perception, knowledge, and climate change perception—commonly argued to be key drivers—are insignificant or weak. The models explain 55%–86% of the variance in adaptation behaviors. Results suggest that the focus of adaptation efforts may need to shift from risk perception and climate change perception to efficacy and social norms.

Why the St. Francis Dam Collapsed

Scientific American | June 1st, 1928

St. Francis dam was constructed on the San Francisquito fault, a geological feature known for a number of years and made the subject of publication illustrated by map

St. Francis dam was constructed on the San Francisquito fault, a geological feature known for a number of years and made the subject of publication illustrated by maps, chief among these being that published several years ago by the Seismological Society of America, which shows the major faults of  California. This statement, made March 22nd by Harry R. Johnson, consulting geologist of Los Angeles, speaking in San Francisco before the delegates to the convention of the American Association of Petroleum Geologists, created a profound impression, accompanied as it was by an analysis of the condition of the fault at that particular place. Mr. Johnson prefaced his report by saying that the advisability of making it had been discussed with other delegates, and that it had been decided that such a public report was advisable in view of the fact that "the public mind had been deluged by the wildest assortment of theories as to the cause of the catastrophe."