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Tag Archive: groundwater

  1. Groundwater depletion could be significant source of atmospheric carbon dioxide

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    • If left to its own devices, this carbon-rich water remains below ground for hundreds to thousands of years before surfacing in oceans or freshwater bodies. But humans are now extracting groundwater at an unprecedented pace to sustain a growing population

    November 16, 2017 American Geophysical Union Read full ScienceDaily article here

    Humans may be adding large amounts of carbon dioxide to the atmosphere by using groundwater faster than it is replenished, according to new research. This process, known as groundwater depletion, releases a significant amount of carbon dioxide into the atmosphere that has until now been overlooked by scientists in calculating carbon sources, according to the new study.

    The study’s authors estimate groundwater depletion in the United States could be responsible for releasing 1.7 million metric tons (3.8 billion pounds) of carbon dioxide to the atmosphere every year.

    Based on these figures, groundwater depletion should rank among the top 20 sources of carbon emissions documented by the US Environmental Protection Agency (EPA) and the Intergovernmental Panel on Climate Change (IPCC). This would mean the carbon dioxide emitted through groundwater depletion is comparable to the carbon generated from aluminum, glass, and zinc production in the United States, according to the study’s authors….

    …Rain falling from the sky contains the same amount of carbon dioxide as is present in the atmosphere. But soil carbon dioxide levels are up to 100 times greater than carbon dioxide levels in the atmosphere, because soil microbes degrade organic carbon into carbon dioxide. When rainwater hits the ground and percolates through Earth’s rocks and sediments, the water dissolves extra carbon produced by these microbes.

    If left to its own devices, this carbon-rich water remains below ground for hundreds to thousands of years before surfacing in oceans or freshwater bodies. But humans are now extracting groundwater at an unprecedented pace to sustain a growing population….

    …Groundwater depletion’s impact on carbon emissions is significant yet relatively small compared to the leading contributors, according to the authors. For example, scientists estimate fossil fuel combustion in the United States is responsible for releasing more than 5 billion metric tons (11 trillion pounds) of carbon dioxide into the atmosphere every year, close to 3,000 times the amount released from groundwater depletion. Still, the study authors argue that understanding all sources of carbon dioxide emissions is important for making accurate climate change projections and finding solutions….

    Warren W. Wood, David W. Hyndman. Groundwater Depletion: A Significant Unreported Source of Atmospheric Carbon Dioxide. Earth’s Future, 2017; DOI: 10.1002/2017EF000586

  2. Groundwater recharge in the American west under climate change

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    November 16, 2017 University of Arizona  read full ScienceDaily article here

    Groundwater recharge in the Western US will change as the climate warms — the dry southern regions will have less and the northern regions will have more, according to new research. The new study covers the entire US West, from the High Plains states to the Pacific coast, and provides the first detailed look at how groundwater recharge may change as the climate changes. Groundwater is an important source of freshwater, particularly in the West.

    Groundwater…. is often used to make up for the lack of surface water during droughts, the authors note. In many areas of the West, groundwater pumping currently exceeds the amount of groundwater recharge.

    “The portions of the West that are already stretched in terms of water resources — Arizona, New Mexico, the High Plains of Texas, the southern Central Valley — for those places that are already having problems, climate change is going to tighten the screws,” Meixner said….

    R. Niraula, T. Meixner, F. Dominguez, N. Bhattarai, M. Rodell, H. Ajami, D. Gochis, C. Castro. How Might Recharge Change Under Projected Climate Change in the Western U.S.? Geophysical Research Letters, 2017; 44 (20): 10,407 DOI: 10.1002/2017GL075421

  3. Nitrogen surplus from agriculture impacts groundwater, according to 70 years of monitoring

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    • A 70 years time-series of monitoring data relays a clear message: When farmers apply more nitrogen to their fields than their crops can absorb, the amount of nitrogen in the groundwater increases. When less nitrogen leaches from the soil, due to either improved management or reduced nitrogen application, the amount found in the groundwater decreases.
    • the study also found that socio-economic development stimulates adoption of measures to protect the environment and that economic growth can curb environmental degradation.
    September 26, 2017 Aarhus University  Read full ScienceDaily article here
    A new study based on 70 years of monitoring data highlights the importance of a consistent national groundwater monitoring program and the need for development of future effective nitrogen mitigation measures in intensive agriculture worldwide in order to protect groundwater resources….

    …In the years 1946 to the mid-1980s nitrogen surplus increased continually. Increasing environmental awareness and national environmental plans have since then curbed this trend — while economic growth continues. Like the nitrogen surplus, the nitrate concentrations in oxic (oxygen present) water reached its peak around the turning point in the 1980s….

    Birgitte Hansen, Lærke Thorling, Jörg Schullehner, Mette Termansen, Tommy Dalgaard. Groundwater nitrate response to sustainable nitrogen management. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-07147-2

  4. CA: More than 99 percent of sustainable groundwater agencies have been formed

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    published on August 28, 2017 – 3:48 PM
    Written by The Business Journal Staff- full article here

    In what the state is billing as “a major step toward sustainable groundwater management in California,” more than 99 percent of the state’s groundwater basins have met a key deadline in reporting groundwater pumping.

    According to the state’s Sustainable Groundwater Management Act (SGMA) of 2014, key stakeholders of the state’s 127 high- and medium-priority groundwater basins were required to form a Groundwater Sustainability Agency (GSA) to manage groundwater pumping. The deadline for formation of the GSAs was June 30, and as of this week, more than 99 percent had been formed.

    …The next step for SGMA compliance is to create and implement groundwater sustainability plans that describe the plan for bringing “basins into balanced levels of pumping and recharge.” Basins identified as critically overdrafted are required to have sustainability plans in place by Jan. 21, 2020, while all other high- and medium-priority basins have until Jan. 31, 2022, to adopt plans.\

  5. Study: Heavy Storms May Be Enough to Recharge Central Valley Groundwater

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    • A handful of storms each year could provide enough water to offset annual groundwater overdraft in California’s Central Valley– but work is needed to capture and distribute that water.

    Matt Weiser August 21, 2017  read full Water Deeply article here

    California’s Sustainable Groundwater Management Act, passed in 2014, requires some 250 groundwater basins throughout the state to halt the overdraft in their aquifers. The big question for everyone is: Where will the water come from to do that?

    It could come from “high-magnitude flows” – flooding events, essentially, that occur from just a handful of storms every winter. …A new UC Davis study …attempts to quantify these high flows… one of the first efforts to measure how much water might be available for groundwater recharge from these storm events, and the results are surprising.

    …[the authors] estimate that 2.6 million acre-feet of water is available in an average year from these high-magnitude flows…based on real flows that have occurred. They also estimate this water is surplus to both existing water rights and to environmental flow requirements in the Sacramento-San Joaquin Delta…..this amount of water also nearly equals the average annual groundwater overdraft in the state’s Central Valley. This suggests these high-magnitude flows could be an important tool to recharge stressed aquifers. That is, if the water can be captured by groundwater banking projects, the flooding of farm fields and other means.

    Within a few weeks, the results will be presented online in an interactive format at recharge.ucdavis.edu.

    Water Deeply recently interviewed Kocis to learn more about her findings.see interview with the study’s authors here

    Tiffany N Kocis and Helen E Dahlke. Availability of high-magnitude streamflow for groundwater banking in the Central Valley, California. 31 July 2017 Environmental Research Letters, Volume 12, Number 8

    ABSTRACT: California’s climate is characterized by the largest precipitation and streamflow variability observed within the conterminous US. This, combined with chronic groundwater overdraft … creates the need to identify additional surface water sources available for groundwater recharge using methods such as agricultural groundwater banking, aquifer storage and recovery, and spreading basins. High-magnitude streamflow, i.e. flow above the 90th percentile, that exceeds environmental flow requirements and current surface water allocations under California water rights, could be a viable source of surface water for groundwater banking. Here, we present a comprehensive analysis of the magnitude, frequency, duration and timing of high-magnitude streamflow (HMF) for 93 stream gauges covering the Sacramento, San Joaquin and Tulare basins in California…The results suggest that there is sufficient unmanaged surface water physically available to mitigate long-term groundwater overdraft in the Central Valley.

  6. Trading Sustainably: local groundwater markets in CA under the Sustainable Groundwater Management Act (SGMA)

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    Berkeley Law’s Center for Law, Energy and Environment June 2017

    California’s Sustainable Groundwater Management Act [SGMA] opens the door for local groundwater markets but does not provide guidance about when they’d be appropriate as management tools. This report outlines considerations to help evaluate local groundwater markets as a viable tool that contributes to sustainably managing a particular groundwater basin.

    [In SGMA, sustainable yield is defined as the amount of groundwater that can be withdrawn annually without chronically lowering groundwater levels, causing seawater intrusion, degrading water quality, causing land subsidence or depleting interconnected surface water (for example, creeks, streams and rivers) in a manner that causes significant and adverse impacts.]

    Download the Executive Summary:

    Trading Sustainably – Executive Summary (June 2017)

    Download the Report:

    Trading Sustainably: Critical Considerations for Local Groundwater Markets Under the Sustainable Groundwater Management Act (June 2017)

    Copyright 2017 Nell Green Nylen

  7. Climate change to deplete water basins used for irrigation in US

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    Posted: 12 Jul 2017 08:04 AM PDT  read full ScienceDaily article here

    Certain hotspots in the country will experience severe reductions in crop yields by 2050, due to climate change’s impact on irrigation, a new study by climate scientists, economists, and agriculture experts finds. The most adversely affected region, according to the researchers, will be the Southwest. Already a water-stressed part of the country, this region is projected to experience reduced precipitation by midcentury. Less rainfall to the area will mean reduced runoff into water basins that feed irrigated fields.

    Production of cotton, the primary irrigated crop in the Southwest and in southern Arizona in particular, will drop to less than 10 percent of the crop yield under optimal irrigation conditions, the study projects. Similarly, maize grown in Utah, now only yielding 40 percent of the optimal expected yield, will decrease to 10 percent with further climate-driven water deficits.

    In the Northwest, water shortages to the Great Basin region will lead to large reductions in irrigated forage, such as hay, grasses, and other crops grown to feed livestock. In contrast, the researchers predict a decrease in water stress for irrigation in the southern Plains, which will lead to greater yields of irrigated sorghum and soybean.

    Elodie Blanc, Justin Caron, Charles Fant, Erwan Monier. Is Current Irrigation Sustainable in the United States? An Integrated Assessment of Climate Change Impact on Water Resources and Irrigated Crop Yields. Earth’s Future, 2017; DOI: 10.1002/2016EF000473

  8. Groundwater Recharge- from Drought to Deluge and Back Again

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    June 22, 2017 by Judy Corbett Calfornia Economic Summit

    ….Common sense dictates that we build water reserves during rainy years that will carry us through the lean years. While dams have been the reserve strategy in the past, recent experience has shown they have limitations…..UC Merced scientist Mohammad Safeeq has pointed to groundwater storage as a viable option, noting that California has enough unused groundwater storage capacity to hold 850 to 1,300 million-acre feet of water. This dwarfs the state’s current surface water storage capacity of 42 million-acre feet….

    … NRDC and partners studied the effects of 15 years of development in 20 sprawling cities and found that by covering over aquifer recharge areas, each had lost enough groundwater to meet the average daily needs of 1.5 to 3.6 million of their residents….

    …Fortunately, …are currently researching and mapping areas with good recharge potential – areas with soil types that allow water to penetrate accompanied by a geologic makeup under the soil that filters and sends water to the aquifer.

    Once special recharge sites are identified, we need to preserve or restore them. Here, progress is being made in both urban and in rural areas. For example, Santa Cruz and Butte Counties both have general plan language protecting important recharge sites from development.

    The City of Los Angeles Department of Water and Power is now providing incentive programs to schools, homeowners, and businesses to capture stormwater and direct it to areas where it can be absorbed. While naturally recharged groundwater is a very inexpensive, it still requires funding for infrastructure changes, land purchases, and the like. Funding could come from federal, state and/or local entities, including those responsible for flood management…

    To get where we need to go, multi-benefit groundwater recharge projects must expand in number and scale. …working together, they can assure the ultimate success of California’s new Sustainable Groundwater Management Act….

  9. Rising groundwater from sea level rise impacts coastal roads

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    Seacoast roads under new threat from rising sea level

    June 1, 2017 University of New Hampshire

    Some roads, as far as two miles from the shore, are facing a new hazard that currently cannot be seen by drivers — rising groundwater caused by increasing ocean water levels….
    ….Groundwater levels are higher than sea levels and that drives the groundwater discharge to the ocean. But as sea levels begin to rise, this forces groundwater to slowly move up to maintain the equilibrium, inching closer to the pavement base layers that need to stay dry to defend their strength….

    Jayne F. Knott, Mohamed Elshaer, Jo Sias Daniel, Jennifer M. Jacobs, Paul Kirshen. Assessing the Effects of Rising Groundwater from Sea Level Rise on the Service Life of Pavements in Coastal Road Infrastructure. Transportation Research Record: Journal of the Transportation Research Board, 2017; 2639: 1 DOI: 10.3141/2639-01

  10. Deep groundwater aquifers respond rapidly to climate variability

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    February 8, 2017  Science Daily  full article here

    Changes in climate can rapidly impact even the deepest freshwater aquifers according to hydrologists. The researchers found that responses to climate variations can be detected in deep groundwater aquifers faster than expected — in many cases within a year.

    The researchers found that responses to climate variations can be detected in deep groundwater aquifers faster than expected — in many cases within a year. Because rain water may take years to reach deep aquifers through natural infiltration, the findings suggest another factor is involved, such as pumping of aquifers done by agricultural industries….

    Tess A. Russo, Upmanu Lall. Depletion and response of deep groundwater to climate-induced pumping variability. Nature Geoscience, 2017; 10 (2): 105 DOI: 10.1038/ngeo2883