{"id":1175,"date":"2026-05-12T21:46:31","date_gmt":"2026-05-12T21:46:31","guid":{"rendered":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/chapter\/aquifer-tests-and-ideal-drawdown-curves\/"},"modified":"2026-05-13T03:13:59","modified_gmt":"2026-05-13T03:13:59","slug":"aquifer-tests-and-ideal-drawdown-curves","status":"publish","type":"chapter","link":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/chapter\/aquifer-tests-and-ideal-drawdown-curves\/","title":{"raw":"8.3 Aquifer Tests and Ideal Drawdown Curves","rendered":"8.3 Aquifer Tests and Ideal Drawdown Curves"},"content":{"raw":"<div id=\"aquifer-tests-and-ideal-drawdown-curves\" class=\"level1\">\r\n<div id=\"multiwell-aquifer-test\" class=\"level3\">\r\n<h3>Multi\u2011Well Aquifer Test<\/h3>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nThe following is a general procedure for conducting a multi\u2011well constant rate aquifer pumping test which, if properly performed, can be used to develop reliable estimates of [latex]T[\/latex] and [latex]S[\/latex] for the producing formation. To do this, you need the following.\r\n\r\n<\/div>\r\n<ul>\r\n \t<li>A <em>pumping well<\/em> with a pump that allows you to control and measure the pumping rate.<\/li>\r\n \t<li>One or more <em>observation wells<\/em> close enough to the pumping well to experience a measurable drawdown induced by pumping from the pumping well.<\/li>\r\n \t<li>Some means of measuring water levels in the pumping and observation wells at specific times throughout the course of the test; these should be some combination of automatic water level meters and manual measurements.<\/li>\r\n \t<li>A sufficient amount of time to pump the well that will result in a measurable change in water level in the observation wells. Typically, tests are run for at least 12 to 24\u00a0hours, though it is not uncommon for pumping tests to be as short as 2\u00a0hours or as long as 30\u00a0days.<\/li>\r\n \t<li>A plan for properly disposing of the water discharged from the well. Care must be taken to avoid having discharged water flow back into the well, as this will compromise the test. Discharge should drain away from pavements and buildings to avoid flooding and damage to infrastructure. In addition, some areas may require permits or other regulatory compliance approval for discharge to existing streams or bodies of standing water.<\/li>\r\n<\/ul>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nThe general procedure for running an aquifer test is presented here.\r\n\r\n<\/div>\r\n<ul>\r\n \t<li>Measure the <em>static water level<\/em>\u2014that is, the initial water level before pumping begins\u2014in all the wells for a period at least as long as the planned test to determine whether the water levels are stable.<\/li>\r\n \t<li>Start the pump, and immediately begin taking water level measurements in the wells at various intervals\u2014starting with something on the order of every 30\u00a0seconds.<\/li>\r\n \t<li>As time progresses, the rate of drawdown will decrease, and measurements can be taken less frequently.<\/li>\r\n \t<li>Continue pumping for the pre\u2011designated period while continuing to take water level measurements.<\/li>\r\n \t<li>Shut off the pump and measure the <em>recovery<\/em> of water in the pumping well\u2014measure water levels at increments of time until the water level approaches the original static water level.<\/li>\r\n<\/ul>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nA properly documented multi\u2011well aquifer test will produce the following data set:\r\n\r\n<\/div>\r\n<ul>\r\n \t<li>pumping rate;<\/li>\r\n \t<li>distance to each observation well from the pumping well; and a<\/li>\r\n \t<li>table of time versus drawdown measurements for the pumping well and for each observation well.<\/li>\r\n<\/ul>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nThe time versus drawdown data, when plotted on a scatter plot and fit with a line, will form shape that depends on the type of aquifer and presence of boundary conditions within the cone of depression. These curves are used to calculate estimates of [latex]T[\/latex] and [latex]S[\/latex]. Before we get into that, there are some basic concepts that we need to cover concerning the drawdown response of different aquifers to pumping wells.\r\n\r\n<\/div>\r\n<\/div>\r\n<div id=\"drawdown-curves\" class=\"level3\">\r\n<h3>Drawdown Curves<\/h3>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nWhen we discussed storage parameters, we presented the concept of <em>elastic storage<\/em>. This is the response of a confined aquifer to pumping; pressure in the aquifer is released, the aquifer structure compresses, grains and water molecules expand, and water is released from aquifer storage into the well. In a fully confined aquifer, all the water pumped out through the well is released from elastic storage, with no interformational leakage, recharge from above, or changes in saturated thickness. This will result in a curve on a plot of drawdown versus time that looks like <a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>.\r\n\r\n<\/div>\r\n<div data-custom-style=\"Captioned Figure\">\r\n\r\n<img style=\"display: block; margin-left: auto; margin-right: auto; ;width: 5in; height: 2.77655in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file41-2.jpg\" alt=\"\" \/>\r\n\r\n<\/div>\r\n<div data-custom-style=\"Block Text\">\r\n<blockquote>\r\n<div class=\"figcaption-text\">\r\n\r\n<span id=\"X6b37aa4e35ac3cb3635464803ba8c40faee1d12\" class=\"anchor\"><strong>Figure\u00a039\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well installed in a confined aquifer in response to a well pumping from the same aquifer at a constant rate.<\/span>\r\n\r\n<\/div><\/blockquote>\r\n<\/div>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nIn <a href=\"#X9f36c7a6ffac8b70592543f710718dca583fdd8\"><span data-custom-style=\"Hyperlink\">Figure\u00a040<\/span><\/a>, the confined aquifer curve of <a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a> (dashed line) is compared to the response for a confined aquifer with a leaky confining layer (solid line). In this case, the water that is leaking through the confining layer is adding water to the aquifer, replacing water that would otherwise need to be removed from storage and cause drawdown, so the drawdown is less than it is in the fully confined case. The initial part of the curve is like a fully confined curve, but when the leakage becomes significant, drawdown is reduced, and the drawdown curve deviates from the fully confined response. A similar response would occur in an aquifer in connection with a constant head boundary (e.g., a river or lake).\r\n\r\n<\/div>\r\n<div data-custom-style=\"Captioned Figure\">\r\n\r\n<img style=\"display: block; margin-left: auto; margin-right: auto; ;width: 5in; height: 2.77655in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file42-2.jpg\" alt=\"A graph of a leaky aquifer Description automatically generated\" \/>\r\n\r\n<\/div>\r\n<div data-custom-style=\"Block Text\">\r\n<blockquote>\r\n<div class=\"figcaption-text\">\r\n\r\n<span id=\"X9f36c7a6ffac8b70592543f710718dca583fdd8\" class=\"anchor\"><strong>Figure\u00a040\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well in a leaky confined aquifer (solid line) in response to a well pumping at a constant rate. The dashed line is for all the same conditions except it is a fully confined aquifer (<a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>). The bracket represents the period when nearly all water is derived from elastic storage before leakage from the recharge boundary is significant.<\/span>\r\n\r\n<\/div><\/blockquote>\r\n<\/div>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nThe second type of boundary previously discussed is the no\u2011flow boundary. <a href=\"#X6ab95b3ddf94870b641676dee936ac0f0575669\"><span data-custom-style=\"Hyperlink\">Figure\u00a041<\/span><\/a> shows the response in a confined aquifer with a lateral no\u2011flow boundary (solid line) compared to the fully confined, unbounded, aquifer response (dashed line). In an aquifer with a lateral no\u2011flow boundary, the same amount of water moves toward the well but a smaller area contributes water from storage so there is more drawdown, especially in later\u2011stages of the test. Like the previous scenario, the early stage of drawdown matches the fully confined curve, and then deviates from it when the influence of the boundary becomes significant.\r\n\r\n<\/div>\r\n<div data-custom-style=\"Captioned Figure\">\r\n\r\n<img style=\"display: block; margin-left: auto; margin-right: auto; ;width: 5in; height: 2.77655in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file43-2.jpg\" alt=\"A line graph of a curve Description automatically generated with medium confidence\" \/>\r\n\r\n<\/div>\r\n<div data-custom-style=\"Block Text\">\r\n<blockquote>\r\n<div class=\"figcaption-text\">\r\n\r\n<span id=\"X6ab95b3ddf94870b641676dee936ac0f0575669\" class=\"anchor\"><strong>Figure\u00a041\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well in an aquifer influenced by a no\u2011flow boundary (solid line) in response to a well pumping at a constant rate. The dashed line is for all the same conditions except it is a fully confined aquifer (<a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>). The bracket represents the period when nearly all water is derived from elastic storage from a complete circle around the well before the zone between the well and the no-flow boundary decreases its contribution from storage.<\/span>\r\n\r\n<\/div><\/blockquote>\r\n<\/div>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nThe unconfined aquifer is a more complex system, in that the drawdown response (solid line in <a href=\"#X8691e29607b84b642b6a9925b0049994554099d\"><span data-custom-style=\"Hyperlink\">Figure\u00a042<\/span><\/a>) is affected by several processes.\r\n\r\n<\/div>\r\n<ol type=\"1\">\r\n \t<li>The first stage represents release from elastic storage.<\/li>\r\n \t<li>In the second stage, pores are dewatered and the declining water table creates vertical gradients in the flow system; these are equivalent to additional water leaking in from above.<\/li>\r\n \t<li>In the third stage, vertical gradients decrease and depression of the water table significantly reduces the saturated thickness, and therefore, the transmissivity.<\/li>\r\n<\/ol>\r\n<div data-custom-style=\"Captioned Figure\">\r\n\r\n<img style=\"display: block; margin-left: auto; margin-right: auto; ;width: 4.78333in; height: 2.65623in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file44-2.jpg\" alt=\"A graph showing a line and a line Description automatically generated with medium confidence\" \/>\r\n\r\n<\/div>\r\n<div data-custom-style=\"Block Text\">\r\n<blockquote>\r\n<div class=\"figcaption-text\">\r\n\r\n<span id=\"X8691e29607b84b642b6a9925b0049994554099d\" class=\"anchor\"><strong>Figure\u00a042\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well in an unconfined aquifer (solid line) in response to a well pumping at a constant rate. The dashed line is for the fully confined aquifer of similar properties (<a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>). Bracket 1 represents the period when nearly all water is derived from elastic storage near the well. Bracket 2 indicates the period of significant pore dewatering and downward flow from the water table. Bracket 3 shows the stage when pore dewatering slows and the lower water table decreases the aquifer transmissivity.<\/span>\r\n\r\n<\/div><\/blockquote>\r\n<\/div>\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\n<em><strong>Thought Question 8<\/strong>: The dashed curve in Figure 39 represents the Theis curve for drawdown versus time for an ideal confined aquifer. On a copy of Figure 39 add at least 15 points that represent time-drawdown data taken from an observation well during a constant-rate aquifer test such that the first 7-8 points match the Theis curve during the early part of the test, but the remaining points indicate drawdown increasing more rapidly with time than predicted by the Theis equation. How would you interpret this image \u2013 in other words, what does your graph tell you about the aquifer that you are testing?<\/em>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>","rendered":"<div id=\"aquifer-tests-and-ideal-drawdown-curves\" class=\"level1\">\n<div id=\"multiwell-aquifer-test\" class=\"level3\">\n<h3>Multi\u2011Well Aquifer Test<\/h3>\n<div data-custom-style=\"First Paragraph\">\n<p>The following is a general procedure for conducting a multi\u2011well constant rate aquifer pumping test which, if properly performed, can be used to develop reliable estimates of [latex]T[\/latex] and [latex]S[\/latex] for the producing formation. To do this, you need the following.<\/p>\n<\/div>\n<ul>\n<li>A <em>pumping well<\/em> with a pump that allows you to control and measure the pumping rate.<\/li>\n<li>One or more <em>observation wells<\/em> close enough to the pumping well to experience a measurable drawdown induced by pumping from the pumping well.<\/li>\n<li>Some means of measuring water levels in the pumping and observation wells at specific times throughout the course of the test; these should be some combination of automatic water level meters and manual measurements.<\/li>\n<li>A sufficient amount of time to pump the well that will result in a measurable change in water level in the observation wells. Typically, tests are run for at least 12 to 24\u00a0hours, though it is not uncommon for pumping tests to be as short as 2\u00a0hours or as long as 30\u00a0days.<\/li>\n<li>A plan for properly disposing of the water discharged from the well. Care must be taken to avoid having discharged water flow back into the well, as this will compromise the test. Discharge should drain away from pavements and buildings to avoid flooding and damage to infrastructure. In addition, some areas may require permits or other regulatory compliance approval for discharge to existing streams or bodies of standing water.<\/li>\n<\/ul>\n<div data-custom-style=\"First Paragraph\">\n<p>The general procedure for running an aquifer test is presented here.<\/p>\n<\/div>\n<ul>\n<li>Measure the <em>static water level<\/em>\u2014that is, the initial water level before pumping begins\u2014in all the wells for a period at least as long as the planned test to determine whether the water levels are stable.<\/li>\n<li>Start the pump, and immediately begin taking water level measurements in the wells at various intervals\u2014starting with something on the order of every 30\u00a0seconds.<\/li>\n<li>As time progresses, the rate of drawdown will decrease, and measurements can be taken less frequently.<\/li>\n<li>Continue pumping for the pre\u2011designated period while continuing to take water level measurements.<\/li>\n<li>Shut off the pump and measure the <em>recovery<\/em> of water in the pumping well\u2014measure water levels at increments of time until the water level approaches the original static water level.<\/li>\n<\/ul>\n<div data-custom-style=\"First Paragraph\">\n<p>A properly documented multi\u2011well aquifer test will produce the following data set:<\/p>\n<\/div>\n<ul>\n<li>pumping rate;<\/li>\n<li>distance to each observation well from the pumping well; and a<\/li>\n<li>table of time versus drawdown measurements for the pumping well and for each observation well.<\/li>\n<\/ul>\n<div data-custom-style=\"First Paragraph\">\n<p>The time versus drawdown data, when plotted on a scatter plot and fit with a line, will form shape that depends on the type of aquifer and presence of boundary conditions within the cone of depression. These curves are used to calculate estimates of [latex]T[\/latex] and [latex]S[\/latex]. Before we get into that, there are some basic concepts that we need to cover concerning the drawdown response of different aquifers to pumping wells.<\/p>\n<\/div>\n<\/div>\n<div id=\"drawdown-curves\" class=\"level3\">\n<h3>Drawdown Curves<\/h3>\n<div data-custom-style=\"First Paragraph\">\n<p>When we discussed storage parameters, we presented the concept of <em>elastic storage<\/em>. This is the response of a confined aquifer to pumping; pressure in the aquifer is released, the aquifer structure compresses, grains and water molecules expand, and water is released from aquifer storage into the well. In a fully confined aquifer, all the water pumped out through the well is released from elastic storage, with no interformational leakage, recharge from above, or changes in saturated thickness. This will result in a curve on a plot of drawdown versus time that looks like <a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>.<\/p>\n<\/div>\n<div data-custom-style=\"Captioned Figure\">\n<p><img decoding=\"async\" style=\"display: block; margin-left: auto; margin-right: auto; ;width: 5in; height: 2.77655in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file41-2.jpg\" alt=\"\" \/><\/p>\n<\/div>\n<div data-custom-style=\"Block Text\">\n<blockquote>\n<div class=\"figcaption-text\">\n<p><span id=\"X6b37aa4e35ac3cb3635464803ba8c40faee1d12\" class=\"anchor\"><strong>Figure\u00a039\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well installed in a confined aquifer in response to a well pumping from the same aquifer at a constant rate.<\/span><\/p>\n<\/div>\n<\/blockquote>\n<\/div>\n<div data-custom-style=\"First Paragraph\">\n<p>In <a href=\"#X9f36c7a6ffac8b70592543f710718dca583fdd8\"><span data-custom-style=\"Hyperlink\">Figure\u00a040<\/span><\/a>, the confined aquifer curve of <a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a> (dashed line) is compared to the response for a confined aquifer with a leaky confining layer (solid line). In this case, the water that is leaking through the confining layer is adding water to the aquifer, replacing water that would otherwise need to be removed from storage and cause drawdown, so the drawdown is less than it is in the fully confined case. The initial part of the curve is like a fully confined curve, but when the leakage becomes significant, drawdown is reduced, and the drawdown curve deviates from the fully confined response. A similar response would occur in an aquifer in connection with a constant head boundary (e.g., a river or lake).<\/p>\n<\/div>\n<div data-custom-style=\"Captioned Figure\">\n<p><img decoding=\"async\" style=\"display: block; margin-left: auto; margin-right: auto; ;width: 5in; height: 2.77655in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file42-2.jpg\" alt=\"A graph of a leaky aquifer Description automatically generated\" \/><\/p>\n<\/div>\n<div data-custom-style=\"Block Text\">\n<blockquote>\n<div class=\"figcaption-text\">\n<p><span id=\"X9f36c7a6ffac8b70592543f710718dca583fdd8\" class=\"anchor\"><strong>Figure\u00a040\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well in a leaky confined aquifer (solid line) in response to a well pumping at a constant rate. The dashed line is for all the same conditions except it is a fully confined aquifer (<a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>). The bracket represents the period when nearly all water is derived from elastic storage before leakage from the recharge boundary is significant.<\/span><\/p>\n<\/div>\n<\/blockquote>\n<\/div>\n<div data-custom-style=\"First Paragraph\">\n<p>The second type of boundary previously discussed is the no\u2011flow boundary. <a href=\"#X6ab95b3ddf94870b641676dee936ac0f0575669\"><span data-custom-style=\"Hyperlink\">Figure\u00a041<\/span><\/a> shows the response in a confined aquifer with a lateral no\u2011flow boundary (solid line) compared to the fully confined, unbounded, aquifer response (dashed line). In an aquifer with a lateral no\u2011flow boundary, the same amount of water moves toward the well but a smaller area contributes water from storage so there is more drawdown, especially in later\u2011stages of the test. Like the previous scenario, the early stage of drawdown matches the fully confined curve, and then deviates from it when the influence of the boundary becomes significant.<\/p>\n<\/div>\n<div data-custom-style=\"Captioned Figure\">\n<p><img decoding=\"async\" style=\"display: block; margin-left: auto; margin-right: auto; ;width: 5in; height: 2.77655in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file43-2.jpg\" alt=\"A line graph of a curve Description automatically generated with medium confidence\" \/><\/p>\n<\/div>\n<div data-custom-style=\"Block Text\">\n<blockquote>\n<div class=\"figcaption-text\">\n<p><span id=\"X6ab95b3ddf94870b641676dee936ac0f0575669\" class=\"anchor\"><strong>Figure\u00a041\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well in an aquifer influenced by a no\u2011flow boundary (solid line) in response to a well pumping at a constant rate. The dashed line is for all the same conditions except it is a fully confined aquifer (<a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>). The bracket represents the period when nearly all water is derived from elastic storage from a complete circle around the well before the zone between the well and the no-flow boundary decreases its contribution from storage.<\/span><\/p>\n<\/div>\n<\/blockquote>\n<\/div>\n<div data-custom-style=\"First Paragraph\">\n<p>The unconfined aquifer is a more complex system, in that the drawdown response (solid line in <a href=\"#X8691e29607b84b642b6a9925b0049994554099d\"><span data-custom-style=\"Hyperlink\">Figure\u00a042<\/span><\/a>) is affected by several processes.<\/p>\n<\/div>\n<ol type=\"1\">\n<li>The first stage represents release from elastic storage.<\/li>\n<li>In the second stage, pores are dewatered and the declining water table creates vertical gradients in the flow system; these are equivalent to additional water leaking in from above.<\/li>\n<li>In the third stage, vertical gradients decrease and depression of the water table significantly reduces the saturated thickness, and therefore, the transmissivity.<\/li>\n<\/ol>\n<div data-custom-style=\"Captioned Figure\">\n<p><img decoding=\"async\" style=\"display: block; margin-left: auto; margin-right: auto; ;width: 4.78333in; height: 2.65623in;\" src=\"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-content\/uploads\/sites\/42\/2026\/05\/file44-2.jpg\" alt=\"A graph showing a line and a line Description automatically generated with medium confidence\" \/><\/p>\n<\/div>\n<div data-custom-style=\"Block Text\">\n<blockquote>\n<div class=\"figcaption-text\">\n<p><span id=\"X8691e29607b84b642b6a9925b0049994554099d\" class=\"anchor\"><strong>Figure\u00a042\u00a0\u2011\u00a0<\/strong>Plot of drawdown versus time in an observation well in an unconfined aquifer (solid line) in response to a well pumping at a constant rate. The dashed line is for the fully confined aquifer of similar properties (<a href=\"#X6b37aa4e35ac3cb3635464803ba8c40faee1d12\"><span data-custom-style=\"Hyperlink\">Figure\u00a039<\/span><\/a>). Bracket 1 represents the period when nearly all water is derived from elastic storage near the well. Bracket 2 indicates the period of significant pore dewatering and downward flow from the water table. Bracket 3 shows the stage when pore dewatering slows and the lower water table decreases the aquifer transmissivity.<\/span><\/p>\n<\/div>\n<\/blockquote>\n<\/div>\n<div data-custom-style=\"First Paragraph\">\n<p><em><strong>Thought Question 8<\/strong>: The dashed curve in Figure 39 represents the Theis curve for drawdown versus time for an ideal confined aquifer. On a copy of Figure 39 add at least 15 points that represent time-drawdown data taken from an observation well during a constant-rate aquifer test such that the first 7-8 points match the Theis curve during the early part of the test, but the remaining points indicate drawdown increasing more rapidly with time than predicted by the Theis equation. How would you interpret this image \u2013 in other words, what does your graph tell you about the aquifer that you are testing?<\/em><\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"author":8,"menu_order":26,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1175","chapter","type-chapter","status-publish","hentry"],"part":1489,"_links":{"self":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1175","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\/1175\/revisions"}],"predecessor-version":[{"id":1731,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1175\/revisions\/1731"}],"part":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/parts\/1489"}],"metadata":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1175\/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=1175"}],"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=1175"},{"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=1175"},{"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=1175"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}