Water and climate: Recognize anthropogenic drought

Nature Portfolio (Springer Nature) | August 27th, 2015

Water and Energy Sector Vulnerability to Climate Warming in the Sierra Nevada: Simulating the Regulated Rivers of California’s West Slope Sierra Nevada

California Energy Commission (CEC) | August 7th, 2012

Climate warming is expected to affect the beneficial uses of water in the Sierra Nevada, impacting nearly every resident of California. This paper describes the developme

Climate warming is expected to affect the beneficial uses of water in the Sierra Nevada, impacting nearly every resident of California. This paper describes the development and results from an integrated water resource management model encompassing water operations and hydropower generation for the west slope Sierra Nevada spanning the Feather River basin in the north to the Kern River basin in the south at the weekly time step. This model application includes management of reservoirs, run-of-river hydropower plants, water supply demand locations, conveyances, and instream flow requirement. Model validation indicates that most major hydropower turbine flows were simulated well, with wetter years modeled more effectively than drier years. The results of this work indicated that hydropower generation will be reduced by approximately 8 percent with 6°C (10.8°F) warming, consistent with other studies, with a conservative parameterization of no change in precipitation. Reservoir operations adapt to capture earlier and greater runoff volumes that result from earlier and greater runoff due to climate warming. Seasonal compensation in operations is insufficient to overcome warming mediated losses.

Water and Energy Sector Vulnerability to Climate Warming in the Sierra Nevada: Water Year Classification in Non?Stationary Climates

California Energy Commission (CEC) | July 31st, 2012

This paper explores the sensitivity of water indexing methods to climate change scenarios to better understand how water management decisions and allocations will be affe

This paper explores the sensitivity of water indexing methods to climate change scenarios to better understand how water management decisions and allocations will be affected by climate change. Many water management decisions, such as environmental flow requirements and water supply allocations, are based on numerical “water year type” designations. Water year type designations vary by region and index, but most are defined by some measure of runoff in the current water year compared to average historical runoff, with numerical thresholds categorizing year types. Climate change is anticipated to alter the timing and volume of runoff, and change the relative frequency of water year types as presently defined. California’s Sacramento Valley and San Joaquin Valley Indices are used as a case study to examine climatic changes. These indices provide a framework for allocating and transferring water among users. Streamflow estimates for 1951–2099 from the climate-forced Variable Infiltration Capacity hydrologic model are used to estimate potential changes in runoff and water year type frequency, using six global circulation models for the A2 and B1 emissions scenarios. Results vary by emissions scenario and global circulation model, but indicate that critically dry water years in the Sacramento Valley and San Joaquin Valley are expected to be about 8 percent and 32 percent more likely by the latter half of the twenty-first century, respectively, if water year type definitions remain unchanged. If current water year type thresholds are maintained, more years will be classified as dry and less water will be allocated for environmental outflows, perhaps failing to provide adequate hydrologic variability to support species, habitats, and ecosystems. If thresholds are redefined to reflect the historical distribution of year types, the burden of climate change falls to consumptive users and water exporters. This case study illustrates how water policy and allocation frameworks were designed assuming climatic stationarity, and that adapting water policy (or maintaining the status quo) affects which users bear the burden of climate change.

Water Forward 2024 Plan Report - Austin's 100 Year Plan

City of Austin | December 6th, 2024

Water Forward 2024 is Austin’s 100-year integrated water resource plan. The purpose of Water Forward is to develop and implement diverse and environmentally conscious w

Water Forward 2024 is Austin’s 100-year integrated water resource plan. The purpose of Water Forward is to develop and implement diverse and environmentally conscious water management strategies to adapt to growth, drought, and climate change and ensure a sustainable, resilient, equitable, and affordable water future for our community for the next 100 years. Austin Water has developed this plan to address near- and long-term water needs through a collaborative process in alignment with guiding principles crafted to reflect the Austin community’s values. 

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 Recommendations to the Next President

Pacific Institute | September 14th, 2020

The United States faces several severe and worsening water problems. Continuing to neglect these problems will impoverish and sicken this and future generations,

The United States faces several severe and worsening water problems. Continuing to neglect these problems will impoverish and sicken this and future generations, destroy beneficial aquatic ecosystems, and threaten our economy and food supply. Smart water policies will create hundreds of thousands of jobs, improve public health, and speed our economic recovery. In this letter, we offer a short assessment of four key problems and specific recommendations for addressing them.

Water Year 2021 Compound Precipitation and Temperature Extremes in California and Nevada

American Meteorological Society (AMS) | December 23rd, 2022

The most intense 22-yr drought in the western United States since 800 CE (Williams et al. 2022) was extended by compound dry and hot extremes in Water Year 2021 (October

The most intense 22-yr drought in the western United States since 800 CE (Williams et al. 2022) was extended by compound dry and hot extremes in Water Year 2021 (October 2020–September 2021). Compared to an instrumental record that dates to 1895, low precipitation (Fig. 1a) and high temperatures (Fig. 1b) were widespread across the western United States. The intense and prevalent drought has caused water delivery shortages (U.S. Bureau of Reclamation 2021), damaged ecosystems (Wlostowski et al. 2022), and contributed to extreme wildfires (e.g., Fu et al. 2021; Gutierrez et al. 2021; Abolafia-Rosenzweig et al. 2022). California and Nevada (CA–NV) were once again at the epicenter of drought and heat in Water Year 2021 (California Department of Water Resources 2021). This was the first time since 1895 that precipitation fell below –1.5 standardized departures and temperatures exceeded 1.5 standardized departures concurrently for the two-state average (Fig. 1c). Precipitation and temperatures were individually extreme as well, as the former was the second lowest since 1895 and the latter was the second highest. We examine whether the co-occurrence of anthropogenic climate change and La Niña, two principal climate drivers during Water Year 2021, altered the risk of unprecedented compound dry and hot extremes in CA–NV during Water Year 2021. Our assessment investigates the factors related to compound extremes that lead to heightened societal impacts compared to individual extreme events (e.g., AghaKouchak et al. 2020; Zscheischler et al. 2020; W. Zhang et al. 2021).

Water Year 2023: Weather Whiplash, from Drought to Deluge

California Department of Water Resources (DWR) | October 4th, 2023

Water Year 2023 demonstrated California’s high climate variability, ending the state’s driest consecutive three-year period with one of the snowiest years of record.

Water Year 2023 demonstrated California’s high climate variability, ending the state’s driest consecutive three-year period with one of the snowiest years of record. Even though California has been experiencing a theme of aridity in the 21st century (the statewide droughts of 2007-2009, 2012-2019, and 2020-2022), Water Year 2017 was the state’s second wettest in terms of statewide precipitation. Climate change is expected to amplify naturally occurring variability in the long term, potentially result in a shorter wet season for California but one with more extreme atmospheric river storms and hence potentially greater flood damage risk.

Water/Wastewater Utilities and Extreme Climate and Weather Events: Case Studies on Community Response, Lessons Learned, Adaptation, and Planning Needs for the Future

Water Research Foundation | July 21st, 2014

This project consisted of a series of workshops that (1) examined the actions taken by water and wastewater utility practitioners who faced a recent extreme weather and c

This project consisted of a series of workshops that (1) examined the actions taken by water and wastewater utility practitioners who faced a recent extreme weather and climate-related event and documented their planning and response; (2) determined and recorded lessons learned; (3) documented and analyzed the decision process, including decision makers, organizations involved, and data needed for making decisions when faced with an extreme event; and (4) summarized communication approaches used to inform the public. The final report, published by WERF, consists of the workshop results and a series of case studies highlighting lessons learned and recommended actions. Additionally, the case studies were published separately and are available on this project page under Project Resources/Project Papers.

Waterline responses to climate forcing along the North American West Coast

Nature Portfolio (Springer Nature) | June 7th, 2025

Understanding waterline variability at seasonal to interannual timescales is crucial for predicting coastal responses to climate forcing. However, relationships between l

Understanding waterline variability at seasonal to interannual timescales is crucial for predicting coastal responses to climate forcing. However, relationships between large-scale climate variability and coastal morphodynamics remain underexplored beyond intensively monitored sites. This study leverages a newly developed 25-year (1997–2022) satellite-derived waterline dataset along the North American West Coast. Our results reveal distinct latitudinal patterns in seasonal waterline change, with excursions exceeding 25 m in the Pacific Northwest, decreasing to less than 10 m in Southern California and farther south. Waterline fluctuations strongly follow wave power in the Pacific Northwest (R = −0.78), northern California (R = −0.75), and Baja California (R = −0.62), while Baja California Sur aligns more with sea-level variations (R = −0.42). Interannually, waterline change exhibits latitudinal dependence: south of southern California, variability is low, with major erosion confined to strong El Niño-Southern Oscillation (ENSO) events, while northern regions show mixed responses. ENSO-driven storm track shifts modulate winter wave climate, resulting in enhanced (attenuated) erosion from southern California to Baja California Sur during El Niño (La Niña). However, further north, ENSO impacts are less consistent, reflecting a complex interplay of storm track displacement and intensification. These findings highlight the spatial complexity of ENSO-driven morphodynamics and provide a framework for assessing climate-induced coastal vulnerability.