The Seasonal Cycle of Surface Soil Moisture

American Meteorological Society (AMS) | June 29th, 2022

The seasonal cycle contributes substantially to soil moisture temporal variability in many parts of the world, with important implications for seasonal forecasting releva

The seasonal cycle contributes substantially to soil moisture temporal variability in many parts of the world, with important implications for seasonal forecasting relevant to agriculture and the health of humans and ecosystems. There is considerable spatial variability in the seasonal cycle of soil moisture, yet a lack of global observations has hindered the development of parsimonious theories explaining that variability. Here, we use 6 years of global satellite observations to describe and explain the seasonal cycle of surface soil moisture globally. An unsupervised clustering algorithm is used to identify five distinct seasonal cycle regimes. Each seasonal cycle regime typically arises in both hemispheres, on multiple continents, and across substantially different local climates. To explain this spatial variability, we then show that the observed seasonal cycle regimes are reproduced very well by a simple but physically based water balance model, which only uses precipitation and downwelling surface shortwave radiation as inputs, and includes no free parameters. Surprisingly, no information on vegetation or land cover is required. To our knowledge, this is the first characterization of the seasonal cycle of surface soil moisture based on global observations.

The seven Colorado River Basin states letter to the U.S. Bureau of Reclamation, 5/22/23

U.S. Bureau of Reclamation (USBR) | May 22nd, 2023

The shrinking Great Salt Lake contributes to record high dust-on-snow deposition in the Wasatch Mountains during the 2022 snowmelt season

Environmental Research Letters (IOP) | June 15th, 2023

The source of water derived from wells— Essential factors controlling the response of an aquifer to development

American Society of Civil Engineers (ASCE) | May 1st, 1940

The paper presented herewith, as a Ground Water Note, was first published by the American Society of Civil Engineers in its Civil Engineering magazine (p. 277-280

The paper presented herewith, as a Ground Water Note, was first published by the American Society of Civil Engineers in its Civil Engineering magazine (p. 277-280) for May 1940. A number of years ago the Ground Water Branch reprinted the paper in limited quantity for distribution to the field offices and some field personnel. The original paper is faithfully reproduced herein, except for minor changes in notation to conform with current Branch usage. Theis’ extremely lucid discussion of the source of water discharged by wells should be clearly understood by all who would attempt to analyze how a preexisting balanced hydraulic system will adjust to newly imposed well discharge.

The Stakes are Rising: Lessons on Engaging Coastal Communities on Climate Adaptation in Southern California

Cities and the Environment | November 16th, 2017

Preparing for climate change is rising as a priority for many public policy agendas, driving a demand for information that allows communities to identify both cur

Preparing for climate change is rising as a priority for many public policy agendas, driving a demand for information that allows communities to identify both current and projected vulnerabilities to climate change at local and regional levels. In response, a developing climate change adaptation service sector is bringing science and technical training to policy-makers. Approaching adaptation planning through a regional lens is critical, due to the large number of stakeholders and the intensely interconnected nature of geographies, communities, and economies. Decisions made in one jurisdiction will undoubtedly affect its neighbors. In this emerging field, boundary organizations play a unique role in building capacity across jurisdictions and bridging the gaps among various community, science and government stakeholders. The University of Southern California (USC) Sea Grant Program, located in Los Angeles, has developed a robust stakeholder engagement process to help communities plan for the impacts of climate change along the urbanized coastline. In 2016, USC Sea Grant analyzed its climate change adaptation outreach program to gain insights about its effectiveness. Drawing from this analysis, this paper explores: 1) stakeholder processes; 2) communications methods, particularly the challenges of communicating scientific information; 3) barriers to planning and implementation; 4) how to identify community needs; and, 5) what kinds of investments have been made to meet those needs. Four primary lessons are identified: 1) place-based boundary organizations can be an effective broker in establishing trust among stakeholders; 2) the ever-evolving and complex nature of climate science can overwhelm stakeholders and stall progress, so it is important to emphasize key messages provided by the scientific information, rather than dive deep into technical details and methods; 3) adaptive management is a promising approach to help communities move forward; and, 4) lack of significant and sustained funding for adaptation will continue to limit progress, however, even modest investments made at the right time can be impactful. Finally, the paper discusses the challenges USC Sea Grant faced in the first six years of its climate adaptation outreach program, and provides thoughts on how to help communities continue to advance their adaptation planning goals in the years to come.

The State of the Sierra Nevada’s Forests

Sierra Nevada Conservancy | October 2nd, 2014

There is a growing understanding that many Sierra Nevada forests are not healthy and that overgrown forests are susceptible to disease and intense wildfire. There is like

There is a growing understanding that many Sierra Nevada forests are not healthy and that overgrown forests are susceptible to disease and intense wildfire. There is likewise broad consensus that science-based ecological restoration of our Sierra Nevada forests must be dramatically increased in order stem the tide of large, uncharacteristic wildfires. These wildfires threaten the very lifeblood of California -- the forested watersheds of the Sierra Nevada. The State of Sierra Nevada’s Forests Report identifies the wide range of benefits provided by our Sierra Nevada forests and watersheds that are at risk: The Region is the origin of 60% of California’s developed water supply. These watersheds are the primary source of fresh water flowing into the Sacramento-SanJoaquin Delta, California’s water “hub.” The forests of the Sierra Nevada store massive amounts of carbon, assisting in the state’sefforts to combat climate change. The forests and watersheds provide crucial habitat to hundreds of species. The area provides world-class recreational opportunities enjoyed by millions from around the world. The Region is a major producer of wood products and hydro-electric power. Key findings of this report include the following: The United States Forest Service Region 5 (USFS) estimates that between six and nine million acres of lands for which they have management responsibility are in need of restoration. In order to return these lands to ecological health, a two to three times increase in the pace and scale of ecological restoration must occur. The amount of area consumed by fire in the Sierra Nevada continues to increase. More land has burned in the first four-and-a-half-years of this decade than seven entire decades in the past. Between 1984 and 2010, there was a significant increase in the number of acres within a forest fire burning at high-intensity, from an average of 20% in mid-1980s to over 30% by 2010. High-intensity burn areas can experience runoff and erosion rates five to ten times greater than low- or moderate-intensity burn areas. The sediment that is carried in the runoff not only degrades water quality and damages infrastructure, it fills reservoirs, reducing storage capacity. The 2013 Rim Fire, the largest fire in the recorded history of the Sierra Nevada, burned 257,000 acres, almost 40% of which was at high intensity. Estimates are that that fire produced the same amount of greenhouse gas emissions that 2.3 million vehicles produce in a year.

The State Water Project Delivery Capability Report 2023 Addendum - Impacts of Subsidence

California Department of Water Resources (DWR) | May 7th, 2025

The purpose of this addendum is to show how ongoing subsidence effects on the California Aqueduct will impact operation of the State Water Project (SWP). The addendum pro

The purpose of this addendum is to show how ongoing subsidence effects on the California Aqueduct will impact operation of the State Water Project (SWP). The addendum provides information to SWP water users about a potential range of water delivery impacts over the next 20 years if no corrective action is taken to address the subsidence effects. However, the California Department of Water Resources (DWR) is committed to restore the conveyance capacity of the California Aqueduct and has an engineering plan for near-term fixes. DWR is also working with its partners to secure additional funding sources for this work. DWR is confident that the California Aqueduct capacity will be restored and the SWP will not see the impacts outlined in this addendum. Thus, long-term water supply planning activities by water users should rely on the potential future SWP allocation results presented in the 2023 Delivery Capability Report (DCR 2023) released in 2024.

The State Water Project’s Strategic Plan

California Department of Water Resources (DWR) | February 22nd, 2024

The strategic plan, Elevate to ’28, projects the trajectory for the SWP for the next five years.

The strategic plan, Elevate to ’28, projects the trajectory for the SWP for the next five years.

The State Water Resources Control Board's Role in Implementing the Delta Plan

California State Water Resources Control Board (SWRCB) | April 5th, 2011

The Delta Plan should identify the authorities of the State Water Board that may be employed to implement its goals, subgoals, and strategies. The State Water Board’s B

The Delta Plan should identify the authorities of the State Water Board that may be employed to implement its goals, subgoals, and strategies. The State Water Board’s Bay Delta Plan and Delta Strategic Workplan should be incorporated into the Delta Plan.

The Status of Perennial Estuarine Wetlands in the State of California

California State Water Resources Control Board (SWRCB) | September 13th, 2008

The statewide initiative to monitor the condition of wetlands has produced a report on the status of wetlands in California’s estuaries. The report is the mos

The statewide initiative to monitor the condition of wetlands has produced a report on the status of wetlands in California’s estuaries. The report is the most comprehensive evaluation ever conducted on the overall health of any class of wetlands in California. It provides an estimate of how much estuarine wetland exists in California and the health of those wetlands. Benefits of the Report The report offers multiple benefits to wetland managers and policy-makers: It establishes a baseline of data in estuaries against which to measure future progress toward the state’s “No Net Loss of Wetlands” policy. Legislators and other policy makers can use the data to determine if wetland protection policies and programs are working and if the public is getting a return for its investment in wetlands. It helps local wetland managers compare the condition of their estuarine wetland or restoration project against the baseline for their region. It satisfies some important legal requirements, including a federal requirement that the state report on the status of wetlands to the U.S. Environmental Protection Agency (U.S. EPA) every two years. The Basics The report studied four questions: Where are the state’s estuarine wetlands, and how much do we have? What is the condition of existing estuarine wetlands statewide, and how does their condition vary by region? What are the primary causes of stress to wetland health, and do those causes vary among different coastal regions? How does the overall health of estuarine wetland restoration projects compare with similar wetlands in their region?