A real-time groundwater management model using data assimilation

American Geophysical Union (AGU) | June 30th, 2011

We apply the proposed management model to the Aquifer Storage and Recovery (ASR) Project of the Las Posas Groundwater Basin in southern California. The adapted nudging al

We apply the proposed management model to the Aquifer Storage and Recovery (ASR) Project of the Las Posas Groundwater Basin in southern California. The adapted nudging algorithm is used to estimate the missing pumping rates of private wells. We then use the estimated pumping rates in a real-time groundwater management model to improve management decisions of the ASR well fields.

A regional high resolution AI weather model for the prediction of atmospheric rivers and extreme precipitation

Nature Portfolio (Springer Nature) | December 12th, 2025

Accurate precipitation forecasting often relies on high-resolution numerical weather prediction (NWP) models, which are essential for capturing fine-scale and nonlinear a

Accurate precipitation forecasting often relies on high-resolution numerical weather prediction (NWP) models, which are essential for capturing fine-scale and nonlinear atmospheric dynamics. However, the computational demands of these models can be substantial. Leveraging recent advancements in artificial intelligence (AI), we present a stretched-grid AI-driven weather model with 6-km horizontal grid increments over the Western United States and ~31 km in other regions globally. The model employs an autoregressive framework to generate forecasts in minutes and is evaluated against global and regional NWP systems, as well as a lower-resolution AI model. Our results show that the regional AI model reduces 24-h accumulated precipitation errors, performs competitively with the regional NWP model, and effectively captures extreme precipitation events, particularly those linked to atmospheric rivers, which global coarser models often underestimate. This work underscores the potential of regional, high-resolution AI models for precipitation forecasting at km-scales, and discusses some of the challenges for future development.

A Research Guide to California Water Law

Loyola Law School | February 21st, 2017

California water law is a complex subject. It is governed by both state and federal law, and is part property law and part environmental law. This topic has important his

California water law is a complex subject. It is governed by both state and federal law, and is part property law and part environmental law. This topic has important historical roots, based in common law concepts of private rights to water, but is now dominated by federal legislation aimed at achieving environmental purposes. Adding to this complexity is the existence of a large number of federal, state and local agencies which play a role in the allocation and management of the state’s water resources. This research guide explains the basic concepts a researcher needs in order to begin understanding the current legal regime that controls the water of California. The guide covers a wide variety of resources, both print and online, some of which are freely available but others only through paid subscriptions. The greater emphasis is on California statutes, cases and regulations, but the secondary sources discussed will provide the necessary explanation of how federal law applies.

A Review of Delta Fish Population Losses from Pumping Operations in the Sacramento-San Joaquin River Delta

Sacramento Regional County Sanitation District (RegionalSan) | January 30th, 2010

To reduce fish loss at the pumps, the state and federal water export facilities operate facilities which are designed to salvage fish from the water and return them to th

To reduce fish loss at the pumps, the state and federal water export facilities operate facilities which are designed to salvage fish from the water and return them to the Delta. Fish facilities include the SWP Skinner Fish Protection Facility and CVP Tracy Fish Collection Facility. The fish facilities utilize two sets of louvers to prevent fish from entering further into water project operations and ultimately the powerful pumps. The louvers concentrate fish so that they can be removed prior to the water diversions. However, these fish salvage operations are inefficient, as high numbers of fish are lost due to predation in the waterways leading to the fish facilities, and the louvers are inefficient.

A Review of the History of Water Use throughout the Klamath River Basin

University of California, Davis (UC Davis) | April 15th, 2003

Water in the Klamath River Basin has been put to use by humans for thousands of years. Beginning with Indian tribes that lived in the area, who used the rivers for fishin

Water in the Klamath River Basin has been put to use by humans for thousands of years. Beginning with Indian tribes that lived in the area, who used the rivers for fishing through to the European settlers who used water for mining or agriculture, Klamath water has been recognized as a precious resource. Many conflicts have risen over the past two centuries as a result. This paper will discuss the uses of water throughout the history of the Klamath River Basin culminating in the Klamath Project and its effects leading to the current Klamath Basin ‘crisis’ .

A Review of the Hydrologic Response Mechanisms During Mountain Rain-on-Snow

Frontiers in Earth Science (Frontiers) | April 26th, 2022

Mountain rain-on-snow (ROS) generates large flooding events worldwide. Climate warming will enhance the frequency, magnitude, and widespread nature of these events. Past

Mountain rain-on-snow (ROS) generates large flooding events worldwide. Climate warming will enhance the frequency, magnitude, and widespread nature of these events. Past studies indicate rainfall, not snowmelt, typically drives much of the runoff response during ROS. However, there is substantial event-to-event variability—resulting from shifting atmospheric drivers and nuanced physical mechanisms governing water flow through a snowpack. Historically, turbulent fluxes were assumed to dominate the energy balance for snowmelt during ROS. Recent research nonetheless suggests that other components of the energy balance might be larger drivers depending on: 1) the time of year; 2) the elevation; and 3) the aspect of the slope. This mini review summarizes the literature on the physical processes governing ROS and proposes that moving forward we utilize the terms “active” and “passive” to describe a snowpack’s contribution (via snowmelt) to terrestrial water input (TWI) during ROS. Active snowpacks readily contribute meltwater to TWI via the energy balance, bolstering rainfall-runoff totals. Passive snowpacks do not melt, but simply convey rainwater through the snow matrix. In both snowpack cases, preferential flow paths enhance transmissivity. This proposed classification scheme will help researchers and water managers better communicate and interpret past findings, and aid in forecasting discussions of future events.

A Review of the SFPUC’s Retail and Wholesale Customer Water Demand Projections

Pacific Institute | July 26th, 2007

In an effort to satisfy the future water needs of its wholesale customers, the San Francisco Public Utilities Commission (SFPUC) commissioned a series of comprehensive as

In an effort to satisfy the future water needs of its wholesale customers, the San Francisco Public Utilities Commission (SFPUC) commissioned a series of comprehensive assessments on the area’s future water demand, conservation potential, and recycled water potential. Based on these studies, the SFPUC projects that by 2030, the total water demand of its wholesale and retail customers will increase by 14%, or 33 million gallons per day (mgd). To meet this projected demand, the SFPUC proposes to divert an additional 25 mgd from the Tuolumne River. In response to the SFPUC’s proposal, the Tuolumne River Trust asked the Pacific Institute to independently review the SFPUC wholesale and retail customer demand projections along with the companion re-ports on water conservation and recycled water. Our analysis reveals that the SFPUC’s studies are inadequate. They may significantly overestimate future regional demand for water. Furthermore, they underestimate the potential for cost-effective demand management and recycled water.

A Review of the Use of Science and Adaptive Management in California's Draft Bay Delta Conservation Plan

National Academy of Sciences (NAS) | January 1st, 2011

The San Francisco Bay Delta Estuary is a large, complex estuarine ecosystem in California. It has been substantially altered by dikes, levees, channelization, pumps,

The San Francisco Bay Delta Estuary is a large, complex estuarine ecosystem in California. It has been substantially altered by dikes, levees, channelization, pumps, human development, introduced species, dams on its tributary streams and contaminants. The Delta supplies water from the state's wetter northern regions to the drier southern regions and also serves as habitat for many species, some of which are threatened and endangered. The restoration of water exacerbated tensions over water allocation in recent years, and have led to various attempts to develop comprehensive plans to provide reliable water supplies and to protect the ecosystem. One of these plans is the Bay Delta Conservation Plan (BDCP). The report, A Review of the Use of Science and Adaptive Management in California's Draft Bay Delta Conservation Plan, determines that the plan is incomplete in a number of important areas and takes this opportunity to identify key scientific and structural gaps that, if addressed, could lead to a more successful and comprehensive final BDCP. The plan is missing the type of structure usually associated with current planning methods in which the goals and objectives are specified, alternative measure for achieving the objectives are introduced and analyzed, and a course of action in identified based on analytical optimization of economic, social, and environmental factors. Yet the panel underscores the importance of a credible and a robust BDCP in addressing the various water management problems that beset the Delta. A stronger, more complete, and more scientifically credible BDCP that effectively integrates and utilizes science could indeed pave the way toward the next generation of solutions to California's chronic water problems.

A Review of the Use of Science and Adaptive Management in California’s Draft Bay Delta Conservation Plan

National Academy of Sciences (NAS) | May 5th, 2011

California’s draft Bay Delta Conservation Plan—a draft plan to conserve habitat for endangered and threatened species, while continuing to divert water to agriculture

California’s draft Bay Delta Conservation Plan—a draft plan to conserve habitat for endangered and threatened species, while continuing to divert water to agriculture and domestic water users in central and southern California—is incomplete and contains critical scientific gaps. The Bay Delta is a large, complex ecosystem that supplies water from the state’s wetter northern regions to the drier southern regions, and also serves as habitat for many species. The Bay Delta Conservation Plan describes a proposal to construct a tunnel or canal to divert water from the northern Delta to the south, thus reducing the need to convey water through the Delta. This report reviews the use of science and adaptive management in the draft Bay Delta Conservation Plan and identifies opportunities to develop a more successful plan.

A Salton Sea Chronology (Prehistory-2015)

U.S. Bureau of Reclamation (USBR) | January 14th, 2016