{"id":1369,"date":"2026-05-12T21:47:41","date_gmt":"2026-05-12T21:47:41","guid":{"rendered":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/chapter\/exercise-19\/"},"modified":"2026-05-13T03:35:26","modified_gmt":"2026-05-13T03:35:26","slug":"exercise-19","status":"publish","type":"chapter","link":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/chapter\/exercise-19\/","title":{"raw":"Exercise 19","rendered":"Exercise 19"},"content":{"raw":"
\r\n
\r\n\r\nGroundwater model non-uniqueness is the phenomenon in which different sets of model parameters produce the same groundwater system conditions. It is common practice to use groundwater models to determine system properties by matching model results to field observations such as water levels and groundwater discharge. This process is called calibrating a model. After a match is obtained, the model is typically used to make predictions. However, non-uniqueness can cause the calibration to produce parameters that are not representative of the system, resulting in inaccurate model predictions.\r\n\r\n<\/div>\r\n
\r\n\r\nUse the Groundwater Project interactive educational tool called WTR<\/span><\/a>\u2197 that simulates flow in a land mass between two water bodies with recharge at the surface. This was described briefly in Section 6.3.2. Use the two input data sets shown below which are identical except the second data set has a value of hydraulic conductivity and net recharge that are both twice the values in the first data set.\r\n\r\n<\/div>\r\n
\r\n\r\n\"\"\r\n\r\n<\/div>\r\n
    \r\n \t
  1. How many differences can you see in the output results?<\/li>\r\n \t
  2. How do the water levels differ?<\/li>\r\n \t
  3. How do the flow rates differ?<\/li>\r\n \t
  4. If a hydrogeologist had only head measurements for the system and adjusted parameter inputs until the calculated heads matched the measured heads, would they obtain accurate values of hydraulic conductivity and recharge?<\/li>\r\n \t
  5. If not, what could be measured to provide accurate estimates?<\/li>\r\n \t
  6. Would you trust predictions of a model that matches the water levels, but does not consider the flow balance? Why, or why not?<\/li>\r\n<\/ol>\r\n
    \r\n\r\nSolution for Exercise 19<\/strong><\/span><\/a>\u2ba7\r\n\r\n<\/div>\r\n
    \r\n\r\nReturn to where text linked to Exercise 19<\/strong><\/span><\/a>\u2ba5\r\n\r\n<\/div>\r\n<\/div>","rendered":"
    \n
    \n

    Groundwater model non-uniqueness is the phenomenon in which different sets of model parameters produce the same groundwater system conditions. It is common practice to use groundwater models to determine system properties by matching model results to field observations such as water levels and groundwater discharge. This process is called calibrating a model. After a match is obtained, the model is typically used to make predictions. However, non-uniqueness can cause the calibration to produce parameters that are not representative of the system, resulting in inaccurate model predictions.<\/p>\n<\/div>\n

    \n

    Use the Groundwater Project interactive educational tool called WTR<\/span><\/a>\u2197 that simulates flow in a land mass between two water bodies with recharge at the surface. This was described briefly in Section 6.3.2. Use the two input data sets shown below which are identical except the second data set has a value of hydraulic conductivity and net recharge that are both twice the values in the first data set.<\/p>\n<\/div>\n

    \n

    \"\"<\/p>\n<\/div>\n

      \n
    1. How many differences can you see in the output results?<\/li>\n
    2. How do the water levels differ?<\/li>\n
    3. How do the flow rates differ?<\/li>\n
    4. If a hydrogeologist had only head measurements for the system and adjusted parameter inputs until the calculated heads matched the measured heads, would they obtain accurate values of hydraulic conductivity and recharge?<\/li>\n
    5. If not, what could be measured to provide accurate estimates?<\/li>\n
    6. Would you trust predictions of a model that matches the water levels, but does not consider the flow balance? Why, or why not?<\/li>\n<\/ol>\n
      \n

      Solution for Exercise 19<\/strong><\/span><\/a>\u2ba7<\/p>\n<\/div>\n

      \n

      Return to where text linked to Exercise 19<\/strong><\/span><\/a>\u2ba5<\/p>\n<\/div>\n<\/div>\n","protected":false},"author":8,"menu_order":102,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1369","chapter","type-chapter","status-publish","hentry"],"part":1522,"_links":{"self":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1369","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/wp\/v2\/users\/8"}],"version-history":[{"count":2,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1369\/revisions"}],"predecessor-version":[{"id":1810,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1369\/revisions\/1810"}],"part":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/parts\/1522"}],"metadata":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1369\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/wp\/v2\/media?parent=1369"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapter-type?post=1369"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/wp\/v2\/contributor?post=1369"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/wp\/v2\/license?post=1369"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}