Mokelumne watershed avoided cost analysis: Why Sierra fuel treatments make economic sense

Sierra Nevada Conservancy | April 10th, 2014

High-severity wildfires in forests of California’s Sierra Nevada pose a serious threat to people and nature. Although proactive forest management can reduce the risk of

High-severity wildfires in forests of California’s Sierra Nevada pose a serious threat to people and nature. Although proactive forest management can reduce the risk of high-severity wildfire, the pace and scale of fuel treatments is insufficient, given the growing scope of the problem. Using the upper Mokelumne River watershed as a representative case, we sought to answer the following question: Does it make economic sense to increase investment in fuel treatments to reduce the risk of large, damaging wildfires? Our analysis suggests that the economic benefits of landscape- scale fuel-reduction treatments far outweigh the costs of wildfire. 

Mono Lake in a Changing Climate

University of California, Los Angeles (UCLA) | March 17th, 2026

This summary report provides an accessible overview of the methods and takeaways from using the University of California, Los Angeles Mono Lake Model (UCLA-MLM) to study

This summary report provides an accessible overview of the methods and takeaways from using the University of California, Los Angeles Mono Lake Model (UCLA-MLM) to study Mono Lake’s water level for varying export and climate conditions. This is also intended to be a summary of the main report. This summary was created for policy makers, organizers, community advocates and members of the public.

More extreme precipitation in the world's dry and wet regions

Nature Portfolio (Springer Nature) | March 7th, 2016

Intensification of the hydrological cycle is expected to accompany a warming climate. It has been suggested that changes in the spatial distribution of precipitation will

Intensification of the hydrological cycle is expected to accompany a warming climate. It has been suggested that changes in the spatial distribution of precipitation will amplify differences between dry and wet regions, but this has been disputed for changes over land. Furthermore, precipitation changes may differ not only between regions but also between different aspects of precipitation, such as totals and extremes. Here we investigate changes in these two aspects in the world’s dry and wet regions using observations and global climate models. Despite uncertainties in total precipitation changes, extreme daily precipitation averaged over both dry and wet regimes shows robust increases in both observations and climate models over the past six decades. Climate projections for the rest of the century show continued intensification of daily precipitation extremes. Increases in total and extreme precipitation in dry regions are linearly related to the model-specific global temperature change, so that the spread in projected global warming partly explains the spread in precipitation intensification in these regions by the late twenty-first century. This intensification has implications for the risk of flooding as the climate warms, particularly for the world’s dry regions.

Multi-box mass balance model of PFOA and PFOS in different regions of San Francisco Bay

Chemosphere (Elsevier) | August 3rd, 2020

We present a model to predict the long-term distribution and concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in estuaries comprisi

We present a model to predict the long-term distribution and concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in estuaries comprising multiple intercommunicated sub-embayments. To that end, a mass balance model including rate constants and time-varying water inputs was designed to calculate levels of these compounds in water and sediment for every sub-embayment. Subsequently, outflows and tidal water exchanges were used to interconnect the different regions of the estuary. To calculate plausible risks to population, outputs of the model were used as inputs in a previously designed model to simulate concentrations of PFOA and PFOS in a sport fish species (Cymatogaster aggregata). The performance of the model was evaluated by applying it to the specific case of San Francisco Bay, (California, USA), using 2009 sediment and water sampled concentrations of PFOA and PFOS in North, Central and South regions. Concentrations of these compounds in the Bay displayed exponential decreasing trends, but with different shapes depending on region, compound, and compartment assessed. Nearly stable PFOA concentrations were reached after 50 years, while PFOS needed close to 500 years to stabilize in sediment and fish. Afterwards, concentrations stabilize between 4 and 23 pg/g in sediment, between 0.02 and 44 pg/L in water, and between 7 and 104 pg/g wet weight in fish, depending on compound and region. South Bay had the greatest final concentrations of pollutants, regardless of compartment. Fish consumption is safe for most scenarios, but due to model uncertainty, limitations in monthly intake could be established for North and South Bay catches.

Multi-year predictability of climate, drought, and wildfire in southwestern North America

Nature Portfolio (Springer Nature) | July 26th, 2017

Past severe droughts over North America have led to massive water shortages and increases in wildfire frequency. Triggering sources for multi-year droughts in this region

Past severe droughts over North America have led to massive water shortages and increases in wildfire frequency. Triggering sources for multi-year droughts in this region include randomly occurring atmospheric blocking patterns, ocean impacts on atmospheric circulation, and climate’s response to anthropogenic radiative forcings. A combination of these sources translates into a difficulty to predict the onset and length of such droughts on multi-year timescales. Here we present results from a new multi-year dynamical prediction system that exhibits a high degree of skill in forecasting wildfire probabilities and drought for 10–23 and 10–45 months lead time, which extends far beyond the current seasonal prediction activities for southwestern North America. Using a state-of-the-art earth system model along with 3-dimensional ocean data assimilation and by prescribing the external radiative forcings, this system simulates the observed low-frequency variability of precipitation, soil water, and wildfire probabilities in close agreement with observational records and reanalysis data. The underlying source of multi-year predictability can be traced back to variations of the Atlantic/Pacific sea surface temperature gradient, external radiative forcings, and the low-pass filtering characteristics of soils.

Multiscale drivers of extreme southern California flooding: ENSO, MJO, North Pacific jet, and atmospheric rivers

Nature Portfolio (Springer Nature) | November 20th, 2025

Extreme rainfall and flooding, driven by a powerful atmospheric river (AR) and a persistent Madden-Julian Oscillation (MJO), hit Southern California in February 2024 duri

Extreme rainfall and flooding, driven by a powerful atmospheric river (AR) and a persistent Madden-Julian Oscillation (MJO), hit Southern California in February 2024 during the 2023–2024 El Niño, affecting over 10 million people. ARs are key contributors to extreme rainfall and flooding along the U.S. West Coast. Although the AR-MJO link has been documented, its spatio-temporal variability remains a major forecasting and risk-management challenge. Combining precipitation, stream gauge and demographic data, we quantify the physical drivers and population exposure to this extreme event. Leveraging a Lagrangian MJO precipitation tracking algorithm, we unravel the multiscale interactions responsible for the AR’s development. El Niño favored a large, long-lived MJO that interacted with the North Pacific Jet (NPJ) over more than three weeks. The MJO convective outflow modulated the NPJ by inducing negative potential vorticity advection along the tropopause. The ensuing NPJ extension and acceleration induced explosive cyclogenesis, whose AR-driven moisture transport resulted in extreme rainfall.

Napa County Baseline Data Report, Chapter 16, Groundwater Hydrology

Napa County | November 30th, 2005

This chapter summarizes the basic groundwater hydrology of Napa County and documents the construction of a local integrated groundwater model. The groundwater hydrology a

This chapter summarizes the basic groundwater hydrology of Napa County and documents the construction of a local integrated groundwater model. The groundwater hydrology analysis and model development were designed to establish a baseline of existing conditions to support countywide programs.

National-Scale Flood Hazard Data Unfit for Urban Risk Management

American Geophysical Union (AGU) | July 19th, 2024

New Method for Estimating Landslide Losses from Major Winter Storms in California and Application to the ARkStorm Scenario

American Society of Civil Engineers (ASCE) | May 30th, 2014

ARkStorm is a statewide emergency planning scenario hypothesizing severe atmospheric river storms that transport huge amounts of moisture from the tropical Pacific to Cal

ARkStorm is a statewide emergency planning scenario hypothesizing severe atmospheric river storms that transport huge amounts of moisture from the tropical Pacific to California, where it falls as intense rain. The storm is projected to be similar to historic storms that have struck California in recent decades, but include extended periods of intense rainfall that approach the massive storms of 1861–1862 in total rainfall. A meteorological model for the ARkStorm has been developed from records of the 1969 and 1986 storms, both of which caused widespread landslides and severe damage in California. Estimating the numbers and impact of landslides from the ARkStorm requires models relating rainfall to the number and distribution of landslides and detailed records of the impact of landslides in past storms. Neither of these basic data sets exist. However, models that estimate the areas with the greatest susceptibility to landsliding do exist and can be combined with detailed maps of small areas showing the numbers of landslides triggered in individual storms. This study extrapolated from local landslide damage to private property in past storms by using a new statewide landslide susceptibility map. These methods may provide a framework for other landslide loss estimates, which can be greatly improved with additional data. Records of landslide losses to the state highway system are more complete than records of damage to private property; it was possible to assemble records for only the past 10 years. Even within these short records, the amount of damage to the state highway system appears to be correlated with rainfall. Projecting from these records, the amount of landslide damage to highways and other infrastructure from the ARkStorm can be estimated. Overall, it is estimated that the ARkStorm would trigger landslides that directly cause billions of dollars in damage.

Nitrogen Fertilizer Loading to Groundwater in the Central Valley

University of California, Davis (UC Davis) | October 31st, 2017

Nitrate‐nitrogen is the most common pollutant found in the Central Valley aquifer system of California. This project provides a long‐term assessment of past and curr

Nitrate‐nitrogen is the most common pollutant found in the Central Valley aquifer system of California. This project provides a long‐term assessment of past and current potential nitrogen loading to groundwater on irrigated and natural lands across the entire Central Valley of California using a nitrogen mass balance approach; assesses the long‐term implications for groundwater quality in the Central Valley (Sacramento Valley, San Joaquin Valley, and Tulare Lake Basin); evaluates potential best management practices to reduce groundwater nitrogen loading from irrigated lands; and provides a planning tool to better understand local and regional groundwater quality response to specific best management practices and policy/regulatory actions. The project complements other work to assess the vulnerability of Central Valley groundwater to nitrate contamination, sources of nitrate in groundwater, and how to reduce source loading.