The paradox of irrigation efficiency

American Association for the Advancement of Science (AAAS) | August 24th, 2018

Reconciling higher freshwater demands with finite freshwater resources remains one of the great policy dilemmas. Given that crop irrigation constitutes 70% of global wate

Reconciling higher freshwater demands with finite freshwater resources remains one of the great policy dilemmas. Given that crop irrigation constitutes 70% of global water extractions, which contributes up to 40% of globally available calories (1), governments often support increases in irrigation efficiency (IE), promoting advanced technologies to improve the “crop per drop.” This provides private benefits to irrigators and is justified, in part, on the premise that increases in IE “save” water for reallocation to other sectors, including cities and the environment. Yet substantial scientific evidence (2) has long shown that increased IE rarely delivers the presumed public-good benefits of increased water availability. Decision-makers typically have not known or understood the importance of basin-scale water accounting or of the behavioral responses of irrigators to subsidies to increase IE. We show that to mitigate global water scarcity, increases in IE must be accompanied by robust water accounting and measurements, a cap on extractions, an assessment of uncertainties, the valuation of trade-offs, and a better understanding of the incentives and behavior of irrigators.

The past and future of global river ice

Nature Portfolio (Springer Nature) | January 1st, 2020

More than one-third of Earth’s landmass is drained by rivers that seasonally freeze over. Ice transforms the hydrologic, ecologic, climatic and socio-economic  functi

More than one-third of Earth’s landmass is drained by rivers that seasonally freeze over. Ice transforms the hydrologic, ecologic, climatic and socio-economic  functions of river corridors. Although river ice extent has been shown to be declining in many regions of the world, the seasonality, historical change and predicted future changes in river ice extent and duration have not yet been quantified globally. Previous studies of river ice, which suggested that declines in extent and duration could be attributed to warming temperatures, were based on data from sparse locations. Furthermore, existing projections of future ice extent are based solely on the location of the 0-°C isotherm. Here, using satellite observations, we show that the global extent of river ice is declining, and we project a mean decrease in seasonal ice duration of 6.10 ± 0.08 days per 1-°C increase in global mean surface air temperature. We tracked the extent of river ice using over 400,000 clear-sky Landsat images spanning 1984–2018 and observed a mean decline of 2.5 percentage points globally in the past three decades. To project future changes in river ice extent, we developed an observationally calibrated and validated model, based on temperature and season, which reduced the mean bias by 87 per cent compared with the 0-degree-Celsius isotherm approach. We applied this model to future climate projections for 2080–2100: compared with 2009–2029, the average river ice duration declines by 16.7 days under Representative Concentration Pathway (RCP) 8.5, whereas under RCP 4.5 it declines on average by 7.3 days. Our results show that, globally, river ice is measurably declining and will continue to decline linearly with projected increases in surface air temperature towards the end of this century.

The pattern of fresh‐water flow in a coastal aquifer

American Geophysical Union (AGU) | April 1st, 1959

Formulas are developed for the flow pattern followed by the seaward‐moving fresh ground water as it nears a beach. It is found that, under steady flow conditions, a sha

Formulas are developed for the flow pattern followed by the seaward‐moving fresh ground water as it nears a beach. It is found that, under steady flow conditions, a sharply defined interface is formed between the fresh and salt water. Along the interface the pressure of the static salt water, owing to its greater density, is counterbalanced by the pressures which drive the fresh water seaward. The fresh water escapes through a gap between this interface and the shore line. An increase in the flow of fresh water widens the gap. Tidal action causes a diffusion of salt water across the interface. This salt is carried back to sea with the fresh‐water flow.

The Perennial Streams Assessment (PSA): An Assessment of Biological Condition using the New California Stream Condition Index (CSCI)

California State Water Resources Control Board (SWRCB) | June 1st, 2015

PSA stream surveys found that the majority of stream length in the Sierra Nevada and North Coast is in good biological condition, while the majority of stream len

PSA stream surveys found that the majority of stream length in the Sierra Nevada and North Coast is in good biological condition, while the majority of stream length in the South Coast, Chaparral and Central Valley is in poor or very poor condition. Similarly, most of the stream length draining forested watersheds is in good condition, while most of the stream length draining watersheds dominated by agricultural and urban land use is in poor or very poor condition. On average, stream condition showed no directional change over time, either for better or for worse. Streams where phosphorous concentration or riparian disturbance exceeded thresholds had the greatest relative risk of biological impairment.  

The Pine Flat Project on Kings River, California

Kings River Water Users Committee | December 1st, 1979

The potential of collaborative solutions to improve management of California (United States) wildlands

Restoration Ecology, Society for Ecological Restoration (SER) | November 13th, 2024

The potential of urban irrigation for counteracting carbon-climate feedback

Nature Portfolio (Springer Nature) | March 18th, 2024

The Press and Pulse of Climate Change: Extreme Events in the Colorado River Basin

American Water Resources Association (AWRA) | June 21st, 2022

Extremes in temperature and precipitation are associated with damaging floods, prolonged drought, destructive wildfires, agricultural challenges, compromised human health

Extremes in temperature and precipitation are associated with damaging floods, prolonged drought, destructive wildfires, agricultural challenges, compromised human health, vulnerable infrastructure, and threatened ecosystems and species. Often, the steady and progressive trends (or presses) of rising global temperature are the central focus in how climate impacts are described. However, observations of extreme weather events (or pulses) increasingly show that the intensity, duration and/or frequency of acute events are also changing, resulting in greater impacts on communities and the environment. Describing how the influence of extreme events may shape water management in the Colorado River Basin in clear terms is critical to sound future planning and efforts to manage risk. Three scenario planning workshops in 2019 and 2020 were held as part of a Colorado River Conversations series, identifying potential impacts from multiple intersecting extreme events. Water managers identified climate-related events of concern in the Colorado River Basin that necessitate greater attention and adaptive responses. To support efforts to include consideration of climate-change-driven extremes in water management and planning, we explore the current state of knowledge at the confluence of long-term climate shifts and extreme weather in the Colorado River Basin related to the events of concern that were identified by scenario planning participants.

The Public Trust Doctrine and California Water Law: National Audubon Society v. Department of Water and Power

University of California College of the Law, San Francisco (UC Law SF) | June 15th, 1982

Conflicting demands on dwindling surface water supplies in California have led to frequent challenges of state decisions to grant diversions of water that impair or destr

Conflicting demands on dwindling surface water supplies in California have led to frequent challenges of state decisions to grant diversions of water that impair or destroy ecological, recreational, or other instream uses of surface waters. This Comment examines the fundamental problems of surface water allocation in California and addresses the possibility of incorporating the public trust doctrine into the current water law system. The Comment then evaluates a recent attempt to apply the public trust doctrine in National Audubon Society v. Department of Water and Power. The Comment concludes by offering an alternative means to public trust protection of California's surface waters.

The Public Trust Doctrine in Natural Resource Law: Effective Judicial Intervention

Berkeley Law Scholarship Repository | January 1st, 1969

Public concern about environmental quality is beginning to be felt in the courtroom. Private citizens, no longer willing to accede to the efforts of administrative agenci

Public concern about environmental quality is beginning to be felt in the courtroom. Private citizens, no longer willing to accede to the efforts of administrative agencies to protect the public interest, have begun to take the initiative themselves. One dramatic result is a proliferation of lawsuits in which citizens, demanding judicial recognition of their rights as members of the public, sue the very governmental agencies which are supposed to be protecting the public interest. While this Article was being written, several dozen such suits were initiated-to enforce air and water pollution laws in states where public agencies have been created for that purpose; to challenge decisions of the Forest Service about the use of public land under its control; to question the Secretary of the Interior's regulation of federal offshore oil leases; and, in a myriad of cases against state and local officials, to examine airport extensions, highway locations, the destruction of parklands,  dredging and filling, oil dumping, and innumerable other governmental decisions dealing with resource use and management.