Item talk:Q271239

{

 "USGS Publications Warehouse": {
   "@context": "https://schema.org",
   "@type": "Article",
   "additionalType": "Journal Article",
   "name": "Evaluation of longitudinal dispersivity estimates from simulated forced\u2010 and natural\u2010gradient tracer tests in heterogeneous aquifers",
   "identifier": [
     {
       "@type": "PropertyValue",
       "propertyID": "USGS Publications Warehouse IndexID",
       "value": "70027362",
       "url": "https://pubs.usgs.gov/publication/70027362"
     },
     {
       "@type": "PropertyValue",
       "propertyID": "USGS Publications Warehouse Internal ID",
       "value": 70027362
     },
     {
       "@type": "PropertyValue",
       "propertyID": "DOI",
       "value": "10.1029/2003WR002401",
       "url": "https://doi.org/10.1029/2003WR002401"
     }
   ],
   "journal": {
     "@type": "Periodical",
     "name": "Water Resources Research",
     "volumeNumber": "40",
     "issueNumber": "1"
   },
   "inLanguage": "en",
   "isPartOf": [
     {
       "@type": "CreativeWorkSeries",
       "name": "Water Resources Research"
     }
   ],
   "datePublished": "2004",
   "dateModified": "2018-04-02",
   "abstract": "We simulate three types of forced\u2010gradient tracer tests (converging radial flow, unequal strength two well, and equal strength two well) and natural\u2010gradient tracer tests in multiple realizations of heterogeneous two\u2010dimensional aquifers with a hydraulic conductivity distribution characterized by a spherical variogram. We determine longitudinal dispersivities (\u03b1L) by analysis of forced\u2010gradient test breakthrough curves at the pumped well and by spatial moment analysis of tracer concentrations during the natural\u2010gradient tests. Results show that among the forced\u2010gradient tests, a converging radial\u2010flow test tends to yield the smallest \u03b1L, an equal strength two\u2010well test tends to yield the largest \u03b1L, and an unequal strength two\u2010well test tends to yield an intermediate value. This finding is qualitatively explained by considering the aquifer area sampled by a particular test. A converging radial\u2010flow test samples a small area, and thus the tracer undergoes a low degree of spreading and mixing. An equal strength two\u2010well test samples a much larger area, so the tracer is spread and mixed to a greater degree. Results also suggest that if the distance between the tracer source well and the pumped well is short relative to the lengths over which velocity is correlated, then the \u03b1L\u00a0estimate can be highly dependent on local heterogeneities in the vicinity of the wells. Finally, results indicate that \u03b1L\u00a0estimated from forced\u2010gradient tracer tests can significantly underestimate the \u03b1L\u00a0needed to characterize solute dispersion under natural\u2010gradient flow. Only a two\u2010well tracer test with a large well separation in an aquifer with a low degree of heterogeneity can yield a value of \u03b1L\u00a0that characterizes natural\u2010gradient tracer spreading. This suggests that a two\u2010well test with a large well separation is the preferred forced\u2010gradient test for characterizing solute dispersion under natural\u2010gradient flow.",
   "description": "Article W01512; 15 p.",
   "publisher": {
     "@type": "Organization",
     "name": "American Geophysical Union"
   },
   "author": [
     {
       "@type": "Person",
       "name": "Hsieh, Paul A. pahsieh@usgs.gov",
       "givenName": "Paul A.",
       "familyName": "Hsieh",
       "email": "pahsieh@usgs.gov",
       "identifier": {
         "@type": "PropertyValue",
         "propertyID": "ORCID",
         "value": "0000-0003-4873-4874",
         "url": "https://orcid.org/0000-0003-4873-4874"
       },
       "affiliation": [
         {
           "@type": "Organization",
           "name": "WMA - Office of Quality Assurance",
           "url": "https://www.usgs.gov/mission-areas/water-resources"
         },
         {
           "@type": "Organization",
           "name": "National Research Program - Western Branch",
           "url": "https://www.usgs.gov/centers/arizona-water-science-center"
         },
         {
           "@type": "Organization",
           "name": "WMA - Earth System Processes Division",
           "url": "https://www.usgs.gov/mission-areas/water-resources"
         }
       ]
     },
     {
       "@type": "Person",
       "name": "Tiedeman, Claire R. tiedeman@usgs.gov",
       "givenName": "Claire R.",
       "familyName": "Tiedeman",
       "email": "tiedeman@usgs.gov",
       "identifier": {
         "@type": "PropertyValue",
         "propertyID": "ORCID",
         "value": "0000-0002-0128-3685",
         "url": "https://orcid.org/0000-0002-0128-3685"
       },
       "affiliation": [
         {
           "@type": "Organization",
           "name": "National Research Program - Western Branch",
           "url": "https://www.usgs.gov/centers/arizona-water-science-center"
         },
         {
           "@type": "Organization",
           "name": "WMA - Earth System Processes Division",
           "url": "https://www.usgs.gov/mission-areas/water-resources"
         }
       ]
     }
   ]
 }

}