Progress 01/01/16 to 12/31/17
Outputs
Target Audience:My 2016 paper in PNAS received extensive media attention from many news outlets, including the Washington Post, Time, Sacramento Bee, Business Insider, Smithsonian Magazine, and the Los Angeles Times. I conducted numerous interviews to address questions from media and the general public. The paper has an online impact score of 464, making it in the top 5% of all research outputs scored by Altmetric and ranking 28th of similar articles in PNAS, a very high-impact journal. The level of media attention was not reported in the last reporting period, although these activities occurred then. In addition, I am working on developing an undergraduate course in Civil Engineering at McGill University that will cover groundwater quality issues, including those related to deep groundwater aquifers studied in this project. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?My abstract, Deep groundwater quantity and quality in the southwestern US, has been accepted for oral presentation at the AGU fall meeting in New Orleans, LA. The presentation will take place on December 15, 2017, in the session, H53O: Regional Groundwater Quality, Availability, and Sustainability: Advances, Methods, and Approaches for a Complex, Changing World I. I gained experience in advising students, which is an important role of academic faculty. With the guidance of my primary mentor, I advised an undergraduate and a graduate student. How have the results been disseminated to communities of interest?I presented my research at the NIFA Fellows Program Project Directors' Meeting in August 2017. The fellows in the audience came from a broad range of fields, such as animal science, that are not represented in conferences and workshops that I typically attend. The audience also included NIFA staff. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
California's historic drought was followed by equally historic heavy rainfall and flooding. The cycle of droughts and floods is expected to continue in the future. The state is currently deciding on a $4 billion bond to address future droughts and floods. $80 million is reserved for groundwater sustainability. Even though the drought has ended, farmers are still drilling deeper groundwater wells to combat groundwater level declines, which are slow to rebound. However, deeper groundwater resources are poorly characterized. In my last study (Kang and Jackson, 2016 PNAS), we attempted the first estimate of deep groundwater volume, both fresh and useable, for California's Central Valley, the heart of the state's agricultural production. In this 2016 paper, the primary water quality parameter considered was salinity and total dissolved solids. The follow-up study considers a wider range of water quality parameters, specifically those related to irrigation. Of the four questions in the project's objectives, the first, third, and fourth questions have been partly addressed in Kang and Jackson (2016 PNAS). All four questions are addressed in the second study (Kang, Ayars, and Jackson, In prep). My first question is regarding deep groundwater volume and availability in the Central Valley. The volume of groundwater at depths of up to 3000 m in the Central Valley was estimated to be nearly three times (2900 km3) the previous estimate for fresh water (<3000 ppm TDS) and four times for useable water (<10,000 ppm TDS; 4200 km3) (Kang, Ayars, and Jackson, In prep). These numbers are updates based on additional data from California Department of Conservation's Division of Oil, Gas, and Geothermal Resources (DOGGR) and new data from the US Geological Survey (USGS), the Produced Waters Database (PWD) and the Brackish Waters Database (BWD). They are similar to those published in my 2016 PNAS paper. Substantial quantities of fresh and useable groundwater exist at depths deeper than normally considered in groundwater volume estimates. Including and beyond California, I analyzed data for ten basins in the southwestern US with the most data. We find that the Great Basin has the greatest proportions of fresh and usable deep groundwater. Given the potentially large deep groundwater volumes in many water scarce regions in California and elsewhere, it is important to characterize the resource, guard against subsidence where extracted, and protect it for use in decades and centuries to come. The United Nations Food and Agriculture Organization (FAO) provides guidelines for three usual (Na, Cl, and B) and 17 trace toxic elements (e.g., Al, As, Cr, F, Mn, Pd, Se, Zn). Using recently-released groundwater (USGS BWD) and oil-and-gas data sources (USGS PWD), I characterized deep groundwater quality in terms of toxic contaminants that may limit the use of deep groundwater for irrigation. The characterization involved spatial analyses, including vertical depth profiles. In appreciation of the complex relationship between contaminants and crops and the crop-specific nature of impacts, I worked closely with my collaborating mentor, USDA Research Agricultural Engineer, Dr. James Ayars. We used crop tolerance thresholds to evaluate deep groundwater quality for irrigation purposes. This analysis addresses the second and third questions of the project's objective. My fourth question on opportunities and challenges of using deep groundwater was considered with respect to oil and gas development in the Central Valley. We found that up to 19% of oil and gas wells at the county level were already drilled in fresh and useable groundwater zones. Elsewhere in southwestern US, oil and gas activities and other energy extraction activities, i.e., geothermal wells, were found to be co-located in deep groundwater aquifers. These energy extraction industries pose many challenges to deep groundwater quality due to the increased potential for contamination. For example, many of these wells may act as pathways for contaminants to migrate to shallower fresh and useable groundwater aquifers. However, oil, gas, and geothermal energy development has provided a wealth of data and infrastructure that can be repurposed for characterizing and monitoring groundwater.
Publications
- Type:
Journal Articles
Status:
Other
Year Published:
2018
Citation:
Kang, M, JE Ayars and RB Jackson. Deep groundwater quality for drinking and irrigation uses in the southwestern US. In Prep.
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Progress 01/01/16 to 12/31/16
Outputs
Target Audience:Target audiences reached are farmers and other private citizens in California who are impacted by the on-going groundwater overdraft. I corresponded with a number of people who were interested in my published findings and answered relevant questions by email. I have also been in touch with Katharine Moore of the California Senate Natural Resources and Water Committee about my findings. I have answered questions she had on our findings and have offered to provide any additional information as needed. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?I am the primary convener of oral and poster presentation sessions at the American Geophysical Union held in San Francisco in December 2016. The role includes inviting speakers, reviewing submitted abstracts, and organizing the presentations. The title of the session is "Existing and Legacy Oil and Gas Infrastructure: Characterization, Mitigation, and Management". This session will bring together researchers collecting data on oil and gas, which have proved to be critical in characterizing and protecting deep groundwater. My primary mentor (Robert Jackson) is a co-convener and has provided insight into how these sessions are organized. I am gaining experience in advising students, which is an important role of academic faculty. With the guidance of my primary mentor, I advised an undergraduate at Stanford in her independent study project in the winter quarter, and am also advising a graduate student. How have the results been disseminated to communities of interest?The results have been published in an academic journal (Proceedings of the National Academy of Sciences (PNAS)) as an open access article that is freely available to the public. In addition, the paper was publicized by PNAS and Stanford University and many journalists interviewed me about the paper. The story reached many popular news outlets including Time and LA Times. The results of the PNAS paper will be disseminated to the scientific community in an oral presentation at the American Geophysical Union's Fall Meeting on December 13th, 2016. Currently, my colleagues and I are working with the Creative Director of Media and Communications at the Bill Lane Center for the American West at Stanford University to create 3-D data visualizations of deep groundwater salinity. What do you plan to do during the next reporting period to accomplish the goals?The groundwater volume estimates can be further refined using additional data from DOGGR and other sources (e.g., the USGS produced waters database). The previous study analyzed salinity of deep groundwater in eight counties across California. The next study will focus on the Central Valley and analyze all available data in the Valley to characterize salinity and to refine fresh and useable groundwater volume estimates. In the process, we will compare data sources and identify gaps that can be filled with additional sampling. Groundwater availability studies will be performed using the DOGGR database for fresh and useable groundwater aquifers identified in the first study. The plan is to use analytical solutions of steady-state well flow bounded by a range of drawdowns at set distances (e.g., 1 km). Currently, data such as permeability and aquifer thickness to perform this analysis is being compiled. I will also identify key trace contaminants such as boron that may limit the use of deep groundwater for agriculture and characterize the contaminant using available data. The characterization will involved spatial analyses, including depth profiles, and will identify data gaps. I have been discussing this part of the project with my collaborating mentor, USDA Research Agricultural Engineer, Dr. James Ayars. I will be working closely with him on identifying key trace contaminants of concern for agricultural water use. For the trace element concentrations, I will begin with the USGS produced waters database. I plan to write two papers: (1) Deep groundwater availability in California's Central Valley, and (2) Characterization of trace contaminants in deep useable groundwater.
Impacts
What was accomplished under these goals?
California remains in a drought. In 2015, the state's agricultural economy lost $1.8 billion, up from the $1.5-billion loss in 2014. Farmers are using more groundwater to combat water shortages, which is leading to deeper drilling. However, deeper groundwater resources are poorly characterized. In a new study that I led and published (Kang and Jackson, 2016 PNAS), we attempted the first estimate of deep groundwater volume, both fresh and useable, for California's Central Valley, the heart of the state's agricultural production. The volume of groundwater at depths of up to 3000 m in the Central Valley was estimated to be nearly three times (2700 km3) the previous estimate for fresh water (<3000 ppm TDS) and four times for useable water (<10,000 ppm TDS; 3900 km3). Additional data are needed to refine this estimate. Nonetheless, substantial quantities of fresh and useable groundwater exist at depths deeper than normally considered in groundwater volume estimates. These deeper resources need to be characterized, monitored, and protected. Of the four questions in the project's objectives, the first, third, and fourth questions have been partly addressed in Kang and Jackson (2016 PNAS). This study analyzed public oil and gas databases from the California Department of Conservation's Division of Oil, Gas, and Geothermal Resources (DOGGR). My first question is regarding deep groundwater volume and availability in the Central Valley. I have estimated deep groundwater volumes, as described above, and am compiling data to analyze deep groundwater availability. In order to answer my third question, I determined salinity profiles with depth at the county level, also using oil and gas databases. The data show that fresh and useable groundwater exists at deeper depths, though most of it is in the top 1000 m. Bases of fresh groundwater were compiled and bases of useable groundwater were estimated. These bases provide information on where fresh and useable groundwater is located, which is critical for water quality monitoring and protection. My fourth question on opportunities and challenges of using deep groundwater was considered with respect to oil and gas development in the Central Valley. The opportunities lie in the wealth of data and infrastructure available in the oil and gas industry that can be repurposed for characterizing and monitoring groundwater. However, the oil and gas industry also pose many challenges to deep groundwater quality due to the increased potential for contamination associated with oil and gas activities. We found that up to 19% of oil and gas wells at the county level were already drilled in fresh and useable groundwater zones. In addition, many of these well may act as pathways for contaminants to migrate to shallower fresh and useable groundwater aquifers. Kang M, Jackson RB, 2016. Salinity of deep groundwater in California: water quantity, quality, and protection. Proceedings of the National Academy of Sciences, U.S.A. 113:7768-7773.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Kang, Mary, and Robert B. Jackson, 2016. Salinity of deep groundwater in California: Water quantity, quality, and protection. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1600400113
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