Recent warming of landfalling atmospheric rivers along the west coast of the United States

American Geophysical Union (AGU) | May 30th, 2019

Abstract: Atmospheric rivers (ARs) often generate extreme precipitation, with AR temperature strongly influencing hydrologic impacts by altering the timing and magni

Abstract: Atmospheric rivers (ARs) often generate extreme precipitation, with AR temperature strongly influencing hydrologic impacts by altering the timing and magnitude of runoff. Long‐term changes in AR temperatures therefore have important implications for regional hydroclimate—especially in locations where a shift to more rain‐dominated AR precipitation could affect flood risk and/or water storage in snowpack. In this study, we provide the first climatology of AR temperature across five US West Coast sub‐regions. We then assess trends in landfalling AR temperatures for each sub‐region from 1980 to 2016 using three reanalysis products. We find AR warming at seasonal and monthly scales. Cool‐season warming ranges from 0.69°C to 1.65°C over the study period. We detect monthly‐scale warming of >2°C, with the most widespread warming occurring in November and March. To understand the causes of AR warming, we quantify the density of AR tracks from genesis to landfall, and analyze along‐track AR temperature for each month and landfall region. We investigate three possible influences on AR temperature trends at landfall: along‐track temperatures prior to landfall, background temperatures over the landfall region, and AR temperature over the coastal ocean adjacent to the region of landfall. Generally, AR temperatures at landfall more closely match coastal and background temperature trends than along‐track AR temperature trends. The seasonal asymmetry of the AR warming and the heterogeneity of influences have important implications for regional water storage and flood risk—demonstrating that changes in AR characteristics are complex, and may not be directly inferred from changes in the background climate. Plain Language Summary: Atmospheric river (AR) storms are well known for their ability to accumulate snowpack, provide drought relief, and generate extreme precipitation and flooding along the West Coast of the United States. AR temperature is an important variable for determining the water resource impacts of a given event, such as the ratio of rain to snow delivered by an individual storm. As a result, changes in AR temperature have implications for both water storage and flood risk. We find substantial warming in ARs at both the seasonal and monthly scales, as well as seasonal and regional variations in the amount of warming along the US West Coast. To understand the warming of ARs at the landfall regions, we compare these monthly temperature trends with trends in temperature along the AR tracks, background temperature over the landfall region, and temperature over the coastal ocean adjacent to the landfall region. The most robust warming occurs in November and March, which has important implications for increased regional flood risk and decreased water storage, and motivates further investigation in other AR‐prone regions around the globe.

Recharge Area Identification, Utilization, and Protection Resource Management Strategy

California Department of Water Resources (DWR) | April 29th, 2024

This resource management strategy (RMS) advances water supply augmentation, resilience, and equity in California by providing summaries of the state of knowledge, applica

This resource management strategy (RMS) advances water supply augmentation, resilience, and equity in California by providing summaries of the state of knowledge, applications, and available information and resources on recharge area identification, utilization, and protection.

Recharge Area Protection (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

Recharge areas are those areas that provide the primary means of replenishing groundwater. Good natural recharge areas are those where good quality surface water is able

Recharge areas are those areas that provide the primary means of replenishing groundwater. Good natural recharge areas are those where good quality surface water is able to percolate through the sediments and rocks to the saturated zone which contains groundwater. If recharge areas cease to function properly, it will limit groundwater replenishment and/or groundwater quality for storage or use. Protection of recharge areas requires a number of actions based on two primary goals: (1) ensuring that areas suitable for recharge continue to be capable of adequate recharge rather than being covered by urban infrastructure, such as buildings and roads, and (2) preventing pollutants from entering groundwater to avoid expensive treatment that may be necessary prior to beneficial use. Protection of recharge areas is necessary to maintain the quantity and quality of groundwater in the aquifer. However, protecting recharge areas by itself does not provide a supply of water. Recharge areas are functioning properly when aquifer storage capacity is available, sufficient permeable surface is present, and the adequate supply of good quality water to recharge the aquifer is available. Protecting existing and potential recharge areas allows them to serve as valuable components of a conjunctive management and groundwater strategy.

Recharge net metering (ReNeM) is a novel, cost-effective management strategy to incentivize groundwater recharge

Nature Portfolio (Springer Nature) | October 18th, 2023

Recharge Net Metering to Enhance Groundwater Sustainability

University of California, Berkeley (UC Berkeley) | April 2nd, 2018

Groundwater sustainability depends on balancing aquifer inflows and outflows. Extraction (pumping of groundwater, typically for human use) and recharge (inflow of

Groundwater sustainability depends on balancing aquifer inflows and outflows. Extraction (pumping of groundwater, typically for human use) and recharge (inflow of water to an aquifer from the land surface and streams) are central components of this water balance. Often, increasing demands for groundwater are exacer- bated by stresses on limited surface water supplies. Changes in land use and shifting climate can result in less infiltration of precipitation into the ground, reducing recharge. Increasing water scarcity has led to increased pumping, and in turn, unsustainable management of groundwater in many basins, resulting in depleted supplies, degraded water quality, and other impacts.

Recharge Roundtable Call to Action: Key Steps for Replenishing California Groundwater

Groundwater Resources Association of California (GRA) | September 24th, 2018

The age of tacitly treating groundwater as primarily an extractive resource is over, both for California and the rest of the world. This will require vastly more

The age of tacitly treating groundwater as primarily an extractive resource is over, both for California and the rest of the world. This will require vastly more managed aquifer recharge than ever previously imagined. It was in this spirit of profound concern for the future of not only groundwater resources, but also for water security and sustainability in general, that on October 2, 2017 the Groundwater Resources Association of California (GRA) and the University of California Water Security and Sustainability Research Initiative (UC Water) convened the Recharge Roundtable in Sacramento. The Recharge Roundtable consisted of 50 attendees with a diverse cross-section of disciplines and professions, including water managers, consultants, academics, hydrologists, and social scientists. The strong experience and expertise assembled in this group, together with the sincere interest in solving a daunting water challenge, made the meeting very productive and led to the proposed actions included in this document.

Reclamation’s NEPA Handbook

U.S. Bureau of Reclamation (USBR) | January 31st, 2012

This edition of the Bureau of Reclamation’s (Reclamation) National Environmental Policy Act (NEPA) Handbook has been developed in response to the Council on Environment

This edition of the Bureau of Reclamation’s (Reclamation) National Environmental Policy Act (NEPA) Handbook has been developed in response to the Council on Environmental Quality’s (CEQ) and the U.S. Department of the Interior’s (Interior) implementing regulations on NEPA. These regulations state that each agency will interpret the provisions of NEPA as a supplement to its existing authority and as a mandate to view its policies and missions in the light of its national environmental objectives. This handbook has been designed as a guidance tool for use by all Reclamation staff. It should also be useful to applicants, contractors, tribal representatives, the general public, and others who may be involved in Reclamation’s NEPA process, or those who develop environmental reports for Reclamation’s use in preparing NEPA documents. This handbook describes Reclamation guidance for implementing the National Environmental Policy Act of 1969 (42 United States Code [U.S.C.] 4321, et seq.), CEQ’s Regulations for Implementing the Procedural Provisions (40 Code of Federal Regulations [CFR] Parts 1500–1508), Interior’s NEPA Regulations (43 CFR Part 46), and the Departmental Manual (DM) Chapter 516. This handbook draws these requirements together and provides guidance on how to apply them to Reclamation programs and activities. The Reclamation Manual NEPA Policy (ENV P03) refers to this handbook as the source of additional information on NEPA compliance for Reclamation. The handbook also presents and summarizes other related environmental laws and Executive orders (EO) which should be addressed during NEPA compliance. This handbook provides an overview of NEPA in chapter 2. Chapter 3 contains a general description of the requirements and procedures of NEPA. Chapter 4 provides information on integrating NEPA with other Reclamation activities. Specific information on categorical exclusion checklists (CEC), environmental assessments (EA), and environmental impact statements (EIS) can be found in chapters 5, 6, and 7, respectively. This organizational structure has been selected to allow the user to quickly locate specific, step-by-step information on the different levels of NEPA compliance. Chapter 8 addresses EIS content, and chapter 9 discusses the requirements of a record of decision (ROD). Chapters 10 and 11 present other information that can be useful in the various situations that arise in applying NEPA to Reclamation’s Federal actions. Chapter 12 concludes the handbook with information on gaining additional assistance on NEPA issues. In addition, various issues and special problems are discussed throughout the handbook. Where possible, solutions that have worked historically, or approaches that seem most reasonable, are recommended.

Recommendations for a Modeling Framework to Answer Nutrient Management Questions in the Sacramento-San Joaquin Delta

San Francisco Estuary Institute (SFEI) | March 1st, 2016

Management actions in the Delta related to nutrients could cost billions of dollars to implement in the coming decades depending on decisions that will come before the Ce

Management actions in the Delta related to nutrients could cost billions of dollars to implement in the coming decades depending on decisions that will come before the Central Valley Regional Water Quality Control Board (Water Board). The complexity of the Delta ecosystem and the range of questions to be addressed demand that numerical, processed-based water quality modeling be part of Delta management efforts. In light of this fact, the Water Board convened the Modeling Science Workgroup in 2015, and tasked it with advising on the development and use of water quality models as one component of the Water Board’s Nutrient Research Plan. The Charge to the Modeling Science Workgroup (included in Appendix B) was to provide advice to the Water Board on:  · The types of models would be needed to answer the nutrient management questions raised by stakeholders,  · Organizational arrangements to support and maximize the benefits of models, and  · Cost estimates for the modeling task and how such work might be phased over time. 

Recommendations for Sustainable Groundwater Management

California Water Foundation | April 5th, 2014

The results of this effort are organized and presented as follows in this Report: • A review of the Dialogue process that provides additional details about participati

The results of this effort are organized and presented as follows in this Report: • A review of the Dialogue process that provides additional details about participating stakeholders and their perspectives; • A description of the background and challenges for California’s groundwater management and current efforts to achieve measurable progress toward sustainable management; • A set of key Findings; and • A package of seven policy Recommendations intended to lead to a new state policy for meaningful, measurable improvement in groundwater management within realistic timeframes. The Recommendations in this report reflect the best judgments of CWF about what is needed to achieve sustainable groundwater management while keeping decision making primarily at local and regional levels. CWF remains committed to a constructive public discussion about this critical issue and, ultimately, to meaningful legislative and policy actions.

Recommendations for the Development and Maintenance of a Reference Condition Management Program (RCMP) to Support Biological Assessment of California’s Wadeable Streams

California State Water Resources Control Board (SWRCB) | March 26th, 2009

Direct measures of the ecological condition of waterbodies have received a recent surge in interest within California’s water quality management and regulatory programs

Direct measures of the ecological condition of waterbodies have received a recent surge in interest within California’s water quality management and regulatory programs because biology-based assessments have several advantages over chemistry- or toxicity- based assessments. Biological assessments are more closely linked to the beneficial uses to be protected and chemistry- or toxicity-based criteria usually lack the predictive ability to infer biological condition. Ultimately, California needs to develop biology-based standards, or biocriteria, as a regulatory tool for monitoring and protecting aquatic life use. Biological assessment tools, including biocriteria, attempt to objectively “score” the biological integrity at a given site. A crucial component to the development of assessment tools is understanding biological expectations at reference sites that consist of natural, undisturbed systems. These reference systems set the biological condition benchmarks for comparisons to the site(s) being evaluated. Two recent external reviews of the State Water Board’s Surface Water Ambient Monitoring Program (SWAMP) affirmed the importance of a sound statewide reference condition program (i.e., TetraTech 2002, SPARC 2006). In October 2007, the SWAMP bioassessment committee assembled a technical panel of statewide and national experts in bioassessment. The panel met for three days to develop a set of recommendations that the SWAMP program could use to establish and maintain a comprehensive reference condition management program (RCMP). The program accounts for biological variation caused by natural environmental gradients and balances statewide consistency with the flexibility needed to adapt to California’s diverse regional settings. Furthermore, the plan allows for adaptive refinement over time.