Warren W. Wood, Ward E. Sanford, John A. Cherry, Warren T. Wood
Our recent steady-state mass-balance modeling suggests that most global carbonic-acid weathering of silicate rocks occurs in the vadose zone of aquifer systems not on the surface by atmospheric CO2. That is, the weathering solute flux is nearly equal to the total global continental riverine carbon flux, signifying little atmospheric weathering by carbonic acid. This finding challenges previous carbon models that utilize silicate weathering as a control of atmospheric CO2 levels. A robust analysis utilizing global estimates of groundwater carbon concentration generated by a geospatial machine learning algorithm was coupled with recharge flux in a geographic information system environment to yield a total global groundwater carbon flux of between 0.87 and 0.96 Pg C/year to the surface environment. On discharging to the surface, the carbon is speciated between 0.01 and 0.11 Pg C/year as CaCO3; 0.35 and 0.38 Pg C/year as CO2 gas; and 0.49 and 0.51 Pg C/year as dissolved HCO3−. This total weathering carbon flux was calculated for direct ocean discharge (0.030 Pg C/year); endorheic basins (0.046 Pg C/year); cold-wet exorheic basins (0.058 Pg C/year); warm-dry exorheic basins (0.072 Pg C/year); cold-dry exorheic basins (0.115 Pg C/year); and warm-wet exorheic basins (0.448 Pg C/year).
{"title":"Global Groundwater Carbon Mass Flux and the Myth of Atmospheric Weathering","authors":"Warren W. Wood, Ward E. Sanford, John A. Cherry, Warren T. Wood","doi":"10.1111/gwat.13457","DOIUrl":"10.1111/gwat.13457","url":null,"abstract":"<p>Our recent steady-state mass-balance modeling suggests that most global carbonic-acid weathering of silicate rocks occurs in the vadose zone of aquifer systems not on the surface by atmospheric CO<sub>2</sub>. That is, the weathering solute flux is nearly equal to the total global continental riverine carbon flux, signifying little atmospheric weathering by carbonic acid. This finding challenges previous carbon models that utilize silicate weathering as a control of atmospheric CO<sub>2</sub> levels. A robust analysis utilizing global estimates of groundwater carbon concentration generated by a geospatial machine learning algorithm was coupled with recharge flux in a geographic information system environment to yield a total global groundwater carbon flux of between 0.87 and 0.96 Pg C/year to the surface environment. On discharging to the surface, the carbon is speciated between 0.01 and 0.11 Pg C/year as CaCO<sub>3</sub>; 0.35 and 0.38 Pg C/year as CO<sub>2</sub> gas; and 0.49 and 0.51 Pg C/year as dissolved HCO<sub>3</sub><sup>−</sup>. This total weathering carbon flux was calculated for direct ocean discharge (0.030 Pg C/year); endorheic basins (0.046 Pg C/year); cold-wet exorheic basins (0.058 Pg C/year); warm-dry exorheic basins (0.072 Pg C/year); cold-dry exorheic basins (0.115 Pg C/year); and warm-wet exorheic basins (0.448 Pg C/year).</p>","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"63 1","pages":"14-24"},"PeriodicalIF":2.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11697531/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>Groundwater depletion has been brought to the public's attention lately, beginning with a series of high-profile articles in the <i>New York Times</i>. The articles infer the need for greater federal involvement and control over the nation's groundwater. Separately, the President's Council of Advisors on Science and Technology (PCAST) formed a working group and solicited input on “America's Groundwater Challenges.” The PCAST request suggested federal actions were needed. However, many responses raised questions and concerns about the nature and scope of such actions (PCAST <span>2024a</span>).</p><p>While safeguarding groundwater is a global challenge, the most effective solutions are found at the local or regional aquifer system level. Groundwater occurs in aquifers that are highly variable in size, geology, climate, overlying land use, water quality, and water uses. The response times of groundwater systems to pumping, connections to surface water, recharge characteristics, and environmental functions also vary widely. Each groundwater system requires individual attention.</p><p>Most critically, effective groundwater management and governance require meaningful and continuing engagement of numerous local stakeholders in the decision-making process. People's diverse values about the environment, property rights, livelihood, individual and community economic gains, and current and intergenerational equity come into play, as do diverse perspectives and passions on how to balance the often-competing demands around groundwater use and protection. Communication and facilitation among stakeholders, decisionmakers, scientists, technical experts, and groundwater users play critical roles in structuring informed and productive conversations.</p><p>Consideration of these key attributes is central to achieving sustainable groundwater management. It is also important to recognize that States and Tribes have authority over the allocation and administration of rights to the use of groundwater within their borders. States and Tribes also administer groundwater quality rules, as well as federal water-quality standards if they have achieved federal delegation. As indicated by several responses to the PCAST query, any effort to impose federal oversight on groundwater pumping would face fierce opposition from states, agricultural groups, and others.</p><p>Indeed, PCAST in their final recommendations acknowledged that the federal government does not manage groundwater (PCAST <span>2024b</span>). The question becomes what is the role of the federal government among a host of partners, including state, federal, tribal, regional, and local entities; nonprofits and community-based organizations; university and private researchers; water districts; industry; and landowners?</p><p>Among the multiple ways the federal government can help are financial assistance for managed aquifer recharge, research and support for new technology for desalination, treatment, and water
{"title":"The Federal Role in Addressing Groundwater Depletion","authors":"William M. Alley, Sharon B. Megdal, Thomas Harter","doi":"10.1111/gwat.13454","DOIUrl":"10.1111/gwat.13454","url":null,"abstract":"<p>Groundwater depletion has been brought to the public's attention lately, beginning with a series of high-profile articles in the <i>New York Times</i>. The articles infer the need for greater federal involvement and control over the nation's groundwater. Separately, the President's Council of Advisors on Science and Technology (PCAST) formed a working group and solicited input on “America's Groundwater Challenges.” The PCAST request suggested federal actions were needed. However, many responses raised questions and concerns about the nature and scope of such actions (PCAST <span>2024a</span>).</p><p>While safeguarding groundwater is a global challenge, the most effective solutions are found at the local or regional aquifer system level. Groundwater occurs in aquifers that are highly variable in size, geology, climate, overlying land use, water quality, and water uses. The response times of groundwater systems to pumping, connections to surface water, recharge characteristics, and environmental functions also vary widely. Each groundwater system requires individual attention.</p><p>Most critically, effective groundwater management and governance require meaningful and continuing engagement of numerous local stakeholders in the decision-making process. People's diverse values about the environment, property rights, livelihood, individual and community economic gains, and current and intergenerational equity come into play, as do diverse perspectives and passions on how to balance the often-competing demands around groundwater use and protection. Communication and facilitation among stakeholders, decisionmakers, scientists, technical experts, and groundwater users play critical roles in structuring informed and productive conversations.</p><p>Consideration of these key attributes is central to achieving sustainable groundwater management. It is also important to recognize that States and Tribes have authority over the allocation and administration of rights to the use of groundwater within their borders. States and Tribes also administer groundwater quality rules, as well as federal water-quality standards if they have achieved federal delegation. As indicated by several responses to the PCAST query, any effort to impose federal oversight on groundwater pumping would face fierce opposition from states, agricultural groups, and others.</p><p>Indeed, PCAST in their final recommendations acknowledged that the federal government does not manage groundwater (PCAST <span>2024b</span>). The question becomes what is the role of the federal government among a host of partners, including state, federal, tribal, regional, and local entities; nonprofits and community-based organizations; university and private researchers; water districts; industry; and landowners?</p><p>Among the multiple ways the federal government can help are financial assistance for managed aquifer recharge, research and support for new technology for desalination, treatment, and water ","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"63 1","pages":"4-5"},"PeriodicalIF":2.0,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gwat.13454","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142775944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>As a practicing hydrogeologist, I have assisted many people and communities who have problem wells or water shortages. But when I recently experienced my own water shortage, I realized how much we in developed countries depend on and take for granted that the water will just be there, and will be fit to drink, when we turn on the tap. In late May of this year, thunderstorms and a few tornados rumbled across the midwestern United States, including our home in southern Wisconsin. My wife and I live in a rural area and are accustomed to thunderstorms in the spring. We are also used to occasional electric power outages, which happen three or four times a year and usually last from 15 min to an hour. So, we weren't especially surprised or worried when our lights went out during the storm. Suddenly, our home was silent except for the rain on the windows—no TV, no radio, no internet, no refrigerator, no lights—and no water, because we depend on our domestic well and pump. Our system usually holds enough water and pressure for a couple of toilet flushes and face washes, but that's it. When the blackout lasts 1 to 2 h, no problem. But when it lasts for 24, then 48, then 60 h, as it did this time, we realize how much we take our well, and our water, for granted. We had no water stockpiled. Fortunately, I was able to drive to a convenience store and purchase a few gallons of “pure spring water” to get us through the requisite drinking, face washing, and tooth brushing, but flushing the toilets was a more complicated matter. Our older home has standard toilets, which require about 7 gal per flush (unlike the newer low-flow toilets). I found myself lugging buckets of water up a hill from a nearby stream (and 7 gal weighs around 58 pounds) for flushing toilets and watering our neighbors' horses.</p><p>Obviously, my power outage was just a minor inconvenience compared to the problems of billions of people faced with real disasters and perpetual water shortages. Based on research by Mekonnen and Hoekstra (<span>2016</span>), UNICEF reports that “…four billion people—almost two thirds of the world's population—experience severe water scarcity for at least one month each year, and over two billion people live in countries where water supply is inadequate (https://www.unicef.org/wash/water-scarcity).” This experience made me contemplate the scope of groundwater science and wonder if we are emphasizing the right things in our work and ignoring the big picture while we focus on the small stuff.</p><p><i>Groundwater's</i> publisher, Wiley, lists the top four issue categories addressed by papers in the journal during the past year as, (1) groundwater flow models; (2) groundwater/aquifer recharge; (3) flow/solute transport simulation; and (4) groundwater solute composition and concentrations. These are all important and interesting topics but may not directly address one of the fundamental issues of our time—global water supply and sustainability, the topic of a rece
{"title":"Remembering the Big Picture","authors":"Kenneth R. Bradbury","doi":"10.1111/gwat.13451","DOIUrl":"10.1111/gwat.13451","url":null,"abstract":"<p>As a practicing hydrogeologist, I have assisted many people and communities who have problem wells or water shortages. But when I recently experienced my own water shortage, I realized how much we in developed countries depend on and take for granted that the water will just be there, and will be fit to drink, when we turn on the tap. In late May of this year, thunderstorms and a few tornados rumbled across the midwestern United States, including our home in southern Wisconsin. My wife and I live in a rural area and are accustomed to thunderstorms in the spring. We are also used to occasional electric power outages, which happen three or four times a year and usually last from 15 min to an hour. So, we weren't especially surprised or worried when our lights went out during the storm. Suddenly, our home was silent except for the rain on the windows—no TV, no radio, no internet, no refrigerator, no lights—and no water, because we depend on our domestic well and pump. Our system usually holds enough water and pressure for a couple of toilet flushes and face washes, but that's it. When the blackout lasts 1 to 2 h, no problem. But when it lasts for 24, then 48, then 60 h, as it did this time, we realize how much we take our well, and our water, for granted. We had no water stockpiled. Fortunately, I was able to drive to a convenience store and purchase a few gallons of “pure spring water” to get us through the requisite drinking, face washing, and tooth brushing, but flushing the toilets was a more complicated matter. Our older home has standard toilets, which require about 7 gal per flush (unlike the newer low-flow toilets). I found myself lugging buckets of water up a hill from a nearby stream (and 7 gal weighs around 58 pounds) for flushing toilets and watering our neighbors' horses.</p><p>Obviously, my power outage was just a minor inconvenience compared to the problems of billions of people faced with real disasters and perpetual water shortages. Based on research by Mekonnen and Hoekstra (<span>2016</span>), UNICEF reports that “…four billion people—almost two thirds of the world's population—experience severe water scarcity for at least one month each year, and over two billion people live in countries where water supply is inadequate (https://www.unicef.org/wash/water-scarcity).” This experience made me contemplate the scope of groundwater science and wonder if we are emphasizing the right things in our work and ignoring the big picture while we focus on the small stuff.</p><p><i>Groundwater's</i> publisher, Wiley, lists the top four issue categories addressed by papers in the journal during the past year as, (1) groundwater flow models; (2) groundwater/aquifer recharge; (3) flow/solute transport simulation; and (4) groundwater solute composition and concentrations. These are all important and interesting topics but may not directly address one of the fundamental issues of our time—global water supply and sustainability, the topic of a rece","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"62 6","pages":"820-821"},"PeriodicalIF":2.0,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gwat.13451","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142515291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Artesian Wells of Batavia, Dutch East-Indies 1872 to 1878","authors":"Paul Whincup, Arjen van Schaijk","doi":"10.1111/gwat.13449","DOIUrl":"10.1111/gwat.13449","url":null,"abstract":"","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"63 1","pages":"130-136"},"PeriodicalIF":2.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gwat.13449","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142484115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical modeling offers a valuable alternative to analytical solutions for pumping test analysis. However, little is known about how discretization impacts results accuracy and runtime. This study presents a systematic method for defining the spatiotemporal discretization of pumping test numerical models based on dimensionless parameters. Two types of analysis are considered: one where observations are made in the pumping well, and another one where observations are made in different wells. The influence of the discretization parameters on results accuracy and runtime is investigated and an optimal set of parameters is determined that minimizes runtime while maintaining the maximum error under 1% for an “average” aquifer. Lower runtimes are achieved when the analysis focuses on the pumping well, which is attributed to the steady-state analytical solution approximating drawdown in the well in the numerical scheme employed. Additional tests demonstrate the robustness of the derived set of parameters in different configurations.
{"title":"A Close-to-Optimal Discretization Strategy for Pumping Test Numerical Simulation","authors":"Ronny Figueroa, Etienne Bresciani","doi":"10.1111/gwat.13442","DOIUrl":"10.1111/gwat.13442","url":null,"abstract":"<p>Numerical modeling offers a valuable alternative to analytical solutions for pumping test analysis. However, little is known about how discretization impacts results accuracy and runtime. This study presents a systematic method for defining the spatiotemporal discretization of pumping test numerical models based on dimensionless parameters. Two types of analysis are considered: one where observations are made in the pumping well, and another one where observations are made in different wells. The influence of the discretization parameters on results accuracy and runtime is investigated and an optimal set of parameters is determined that minimizes runtime while maintaining the maximum error under 1% for an “average” aquifer. Lower runtimes are achieved when the analysis focuses on the pumping well, which is attributed to the steady-state analytical solution approximating drawdown in the well in the numerical scheme employed. Additional tests demonstrate the robustness of the derived set of parameters in different configurations.</p>","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"63 1","pages":"105-115"},"PeriodicalIF":2.0,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gwat.13442","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142304684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号