{"id":1326,"date":"2026-05-12T21:47:35","date_gmt":"2026-05-12T21:47:35","guid":{"rendered":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/chapter\/basic-classification-of-hydrogeologic-environments\/"},"modified":"2026-05-13T03:26:22","modified_gmt":"2026-05-13T03:26:22","slug":"basic-classification-of-hydrogeologic-environments","status":"publish","type":"chapter","link":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/chapter\/basic-classification-of-hydrogeologic-environments\/","title":{"raw":"17.2 Basic Classification of Hydrogeologic Environments","rendered":"17.2 Basic Classification of Hydrogeologic Environments"},"content":{"raw":"<div id=\"basic-classification-of-hydrogeologic-environments\" class=\"level1\">\r\n<div data-custom-style=\"First Paragraph\">\r\n\r\nGroundwater occurs everywhere in the subsurface, and almost any geologic setting can host an aquifer even if it only provides small volumes of water. However, there are certain geologic environments that tend to have sufficient porosity and permeability to support a substantial aquifer. Keep in mind that both parameters are necessary\u2014a clay or vuggy basalt unit may have lots of porosity and hold a lot of water, but if the pores are too small or not connected, permeability will be low and well yields will not be adequate. Conversely, a set of fractures in a granite may have an extremely high permeability\u2014because it only takes a small aperture to get a very permeable fracture\u2014but if the matrix porosity is low, a well will quickly drain the fractures and will not yield much water over time.\r\n\r\n<\/div>\r\n<div data-custom-style=\"Body Text\">\r\n\r\nTo understand these systems, we classify five basic geologic settings\u2014with variations within each setting\u2014plus a few special cases.\r\n\r\n<\/div>\r\n<\/div>","rendered":"<div id=\"basic-classification-of-hydrogeologic-environments\" class=\"level1\">\n<div data-custom-style=\"First Paragraph\">\n<p>Groundwater occurs everywhere in the subsurface, and almost any geologic setting can host an aquifer even if it only provides small volumes of water. However, there are certain geologic environments that tend to have sufficient porosity and permeability to support a substantial aquifer. Keep in mind that both parameters are necessary\u2014a clay or vuggy basalt unit may have lots of porosity and hold a lot of water, but if the pores are too small or not connected, permeability will be low and well yields will not be adequate. Conversely, a set of fractures in a granite may have an extremely high permeability\u2014because it only takes a small aperture to get a very permeable fracture\u2014but if the matrix porosity is low, a well will quickly drain the fractures and will not yield much water over time.<\/p>\n<\/div>\n<div data-custom-style=\"Body Text\">\n<p>To understand these systems, we classify five basic geologic settings\u2014with variations within each setting\u2014plus a few special cases.<\/p>\n<\/div>\n<\/div>\n","protected":false},"author":8,"menu_order":76,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1326","chapter","type-chapter","status-publish","hentry"],"part":1516,"_links":{"self":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1326","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\/1326\/revisions"}],"predecessor-version":[{"id":1781,"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1326\/revisions\/1781"}],"part":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/parts\/1516"}],"metadata":[{"href":"https:\/\/books.gw-project.org\/basic-hydrogeology-an-introduction-to-the-fundamentals-of-groundwater-science\/wp-json\/pressbooks\/v2\/chapters\/1326\/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=1326"}],"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=1326"},{"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=1326"},{"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=1326"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}