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Author Heaton, T.H.E.; Talma, A.S.; Vogel, J.C. url  openurl
  Title Origin and history of nitrate in confined groundwater in the western Kalahari Type Journal Article
  Year 1983 Publication Journal of Hydrology Abbreviated Journal  
  Volume 62 Issue 1 Pages 243-262  
  Keywords  
  Abstract Data are presented for nitrate, dinitrogen and argon concentrations and 15N14N ratios in groundwater, with radiocarbon ages up to 40,000 yr. for three confined sandstone aquifers in the western Kalahari of South West Africa/Namibia. The nitrate is probably generated within the soil of the recharge areas, and its production rate during the period 3000-40,000 B.P. has remained between 0.5 and 1.6 meq NO−3l−1 of recharge water, with ° 15N between + 4 and + 8‰. Variations in the amount of nitrate and of “excess air” in groundwater recharge are found, and can only reflect changes in the environmental conditions during recharge. They must therefore be caused by the climatic changes that have taken place during the past 25,000 yr.  
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  ISSN 0022-1694 ISBN Medium  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Heaton1983243 Serial (down) 282  
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Author Vogel, J.C.; Talma, A.S.; Heaton, T.H.E. url  openurl
  Title Gaseous nitrogen as evidence for denitrification in groundwater Type Journal Article
  Year 1981 Publication Journal of Hydrology Abbreviated Journal  
  Volume 50 Issue Pages 191-200  
  Keywords  
  Abstract By investigating the nitrate, oxygen, nitrogen and argon concentrations and 15N14N ratios in artesian groundwater with radiocarbon ages ranging up to 27,000 yr. a process of very slow denitrification in a confined aquifer is demonstrated. The calculated nitrogenisotope fractionation factor associated with this reaction is comparable to that reported for bacterial cultures in vitro and in vivo.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Vogel1981191 Serial (down) 280  
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Author Heaton, T.H.E. url  openurl
  Title Sources of the nitrate in phreatic groundwater in the western Kalahari Type Journal Article
  Year 1984 Publication Journal of Hydrology Abbreviated Journal  
  Volume 67 Issue 1 Pages 249-259  
  Keywords  
  Abstract Elevated levels of nitrate occur in phreatic groundwater in the western Kalahari, Namibia. Nitrate in water containing 0.4–3.1 meq NO−3l−1, of widespread occurrence, has δ15N values in the range +4.9 to +8.0‰, suggesting natural derivation from the soil. The sporadic occurrence of very high levels of nitrate (> 4 meq NO−3l−1), which has δ15N between +9.3 to +18.7‰, reflects pollution derived from animal waste. The importance of considering the possible isotopic effects of denitrification, and the significance of leaching in the nitrogen budget of the Kalahari soil, are also discussed.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Heaton1984249 Serial (down) 278  
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Author Seidl, C.; Wheeler, S.A.; Page, D. url  openurl
  Title Understanding the global success criteria for managed aquifer recharge schemes Type Journal Article
  Year 2024 Publication Journal of Hydrology Abbreviated Journal  
  Volume 628 Issue Pages 130469  
  Keywords Managed Aquifer Recharge (MAR), Fuzzy-set Qualitative Comparative Analysis, Water banking, Groundwater, Water management, Water storage  
  Abstract Water availability and quality issues will only gain importance in the future, with climate change impacts putting increasing pressure on global water resources. Dealing with these challenges requires drawing on all available water management tools, including Managed Aquifer Recharge (MAR). Although MAR has seen increasing global implementation during the last half a century, it is still often overlooked as a management tool. While technical, bio-physical, and hydrogeological aspects of MAR are well researched, this cannot be said for socio-economic and other governance factors. Where information is available, this study seeks to understand the conditions necessary for MAR success. We apply fuzzy-set Qualitative Comparative Analysis on 313 world MAR applications, and also model separately for high- and low-middle-income countries. Results show that sophisticated hydrogeological site understanding and scheme operation is paramount for MAR success, as is utilizing natural water sources for high value end uses. Successful high-income country MAR schemes tend to be large and utilize natural water sources and sophisticated water injection and treatment methods to augment potable water supply; while successful low-middle-income country schemes are not large, older than 20 years, and use gravity infiltration methods and (limited) no water treatment. These findings will help inform the future suitability of MAR application design and its likely success within various contexts.  
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  Call Number THL @ christoph.kuells @ Seidl2024130469 Serial (down) 273  
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Author Sedghi, M.M.; Zhan, H. url  openurl
  Title On the discharge variation of a qanat in an alluvial fan aquifer Type Journal Article
  Year 2022 Publication Journal of Hydrology Abbreviated Journal  
  Volume 610 Issue Pages 127922  
  Keywords Analytical solution, Wedge-shaped aquifer, Image well, Areal recharge  
  Abstract Qanat is a passive (unpumped) horizontal well (or a slant well with a very mild inclined angle) that is capable of extracting water from aquifers by gravity. Many qanats are constructed along the radius of the alluvial fan wedge-shaped aquifers. Analytical modeling of such a qanat-aquifer system provides great benefit for quickly screening different designs of qanats and accessing the performance of qanat discharge in the field. The previous analytical modeling of discharge of qanats, however, did not consider the wedge-shaped aquifers. Thus, the goal of this research is to obtain semi-analytical solutions of discharge variations of qanats in alluvial fan aquifers with nearby pumping wells, subjected to areal recharges due to rainfall. The uniform head boundary is considered inside the qanat (because of its enormous permeability in respect to the background aquifer). The influences of the aquifer lateral boundaries on discharge of qanat and its sensitivity to hydraulic and geometric parameters are explored. The influences of the lateral boundaries on the discharge of qanat due to areal recharge and nearby pumping wells discharge are also explored. The results of this study can be utilized for multiple purposes: 1) to predict the discharge of qanat in an alluvial fan aquifer and explore the influences of the areal recharge and nearby pumping well discharge; 2) to estimate the hydraulic parameters of the alluvial fan aquifer depleted by a qanat; 3) to determine the location of the nearby pumping well to minimize its influences on the discharge of a qanat; 4) to calculate the water budgets of aquifers depleted by qanats and pumping wells and replenished by areal recharge among other applications. This paper is an extension to the work presented by Sedghi and Zhan (2020) (which concerns an infinite unconfined aquifer) for an unconfined alluvial fan aquifer setting.  
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  Notes Approved no  
  Call Number THL @ christoph.kuells @ Sedghi2022127922 Serial (down) 267  
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