{"id":252,"date":"2020-09-29T23:28:10","date_gmt":"2020-09-29T23:28:10","guid":{"rendered":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/?post_type=part&p=252"},"modified":"2020-10-19T00:02:17","modified_gmt":"2020-10-19T00:02:17","slug":"disappearing-groundwater","status":"publish","type":"part","link":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/part\/disappearing-groundwater\/","title":{"raw":"8 Disappearing Groundwater","rendered":"8 Disappearing Groundwater"},"content":{"raw":"Earth has many thousands of aquifers, but only a few dozen aquifers are categorized as major. Thanks to a decade (2003 to 2013) of satellite data collected by a unique NASA Earth-observing mission called the Gravity Recovery and Climate Experiment (GRACE), much is now known about the depletion of many of the major aquifers. Unlike satellite missions that rely on visual images, GRACE measured the tiny space-time variations in Earth\u2019s gravity field, effectively weighing changes in water mass of large aquifers. Figure 70 illustrates groundwater depletion ( - ) or replenishment (+) in millimeters of water per year based on GRACE data for Earth's 37 largest aquifers.\r\n\r\n[caption id=\"attachment_384\" align=\"alignnone\" width=\"1024\"]\"World Figure 70 -<\/strong> Groundwater depletion ( - ) or replenishment (+) in millimeters of water per year for Earth's 37 largest aquifers based on GRACE data from 2003 to 2013 (adapted from NASA\/JPL Caltech, 2015).[\/caption]\r\n\r\nThe GRACE results are consistent with long\u2011term estimates of groundwater extraction. The estimated evolution of groundwater extraction in India from 1950 to 2010 is shown in Figure\u00a071, together with similar time series for a selected group of countries. India\u2019s groundwater extraction rate in 2010 was approximately 251 cubic km per year, equivalent to a quarter of the global rate. The Ganges\u2011Brahmaputra basin suffers aquifer depletion and groundwater pollution stresses including swathes of India, China, Nepal, Bangladesh and Bhutan, which collectively is home to about 10 percent of the Planet\u2019s population. Close to 50 percent of the world\u2019s aquifers may be \u201cpast their tipping point\u201d, which means that a natural recovery would require centuries.\r\n\r\n[caption id=\"attachment_386\" align=\"alignnone\" width=\"757\"]\"Figure Figure 71 -<\/strong> Estimated national groundwater extraction for selected countries from 1950 to 2010 (adapted from Van Der Gunn 2019, with data from Margat and Van Der Gun, 2013).[\/caption]\r\n\r\nThe Nubian system, the biggest non\u2011renewable aquifer (fossil water) in the world, occurs under parts of Egypt, Libya, Sudan and Chad. Mostly underlying Egypt and Libya, it is considered under high\u2011stress due to unsustainable withdrawal rates driven by population growth. Libya depends on the aquifer for about 95 percent of its water.\r\n\r\nThe Nubian system also features one of the few trans boundary aquifer agreements. Worldwide, six trans boundary aquifers exist with specific agreements, and two aquifers with informal accords. The Northwest Saharan aquifer system that underlies 60 percent of Algeria, almost a third of Libya and part of Tunisia is another trans boundary aquifer with high levels of water withdrawals. It also falls under a cooperation pact and is similar to the Nubian system in that it is non\u2011renewable water. The water is used mainly for agricultural irrigation and industry.\r\n\r\nProjections based on current water usage, anticipated population increase and economic growth scenarios suggest substantial shortfalls in water availability in the coming decade, including nearly 600 aquifers that cross sovereign borders. The depletion of aquifers is the most evident of the Planet\u2019s two groundwater problems, the other problem is groundwater pollution. Pollution diminishes the usefulness of the water that remains after aquifer depletion. The failure to manage Earth\u2019s groundwater resources is a threat to the global stability of human society.","rendered":"

Earth has many thousands of aquifers, but only a few dozen aquifers are categorized as major. Thanks to a decade (2003 to 2013) of satellite data collected by a unique NASA Earth-observing mission called the Gravity Recovery and Climate Experiment (GRACE), much is now known about the depletion of many of the major aquifers. Unlike satellite missions that rely on visual images, GRACE measured the tiny space-time variations in Earth\u2019s gravity field, effectively weighing changes in water mass of large aquifers. Figure 70 illustrates groundwater depletion ( – ) or replenishment (+) in millimeters of water per year based on GRACE data for Earth’s 37 largest aquifers.<\/p>\n

\"World
Figure 70 –<\/strong> Groundwater depletion ( – ) or replenishment (+) in millimeters of water per year for Earth’s 37 largest aquifers based on GRACE data from 2003 to 2013 (adapted from NASA\/JPL Caltech, 2015).<\/figcaption><\/figure>\n

The GRACE results are consistent with long\u2011term estimates of groundwater extraction. The estimated evolution of groundwater extraction in India from 1950 to 2010 is shown in Figure\u00a071, together with similar time series for a selected group of countries. India\u2019s groundwater extraction rate in 2010 was approximately 251 cubic km per year, equivalent to a quarter of the global rate. The Ganges\u2011Brahmaputra basin suffers aquifer depletion and groundwater pollution stresses including swathes of India, China, Nepal, Bangladesh and Bhutan, which collectively is home to about 10 percent of the Planet\u2019s population. Close to 50 percent of the world\u2019s aquifers may be \u201cpast their tipping point\u201d, which means that a natural recovery would require centuries.<\/p>\n

\"Figure
Figure 71 –<\/strong> Estimated national groundwater extraction for selected countries from 1950 to 2010 (adapted from Van Der Gunn 2019, with data from Margat and Van Der Gun, 2013).<\/figcaption><\/figure>\n

The Nubian system, the biggest non\u2011renewable aquifer (fossil water) in the world, occurs under parts of Egypt, Libya, Sudan and Chad. Mostly underlying Egypt and Libya, it is considered under high\u2011stress due to unsustainable withdrawal rates driven by population growth. Libya depends on the aquifer for about 95 percent of its water.<\/p>\n

The Nubian system also features one of the few trans boundary aquifer agreements. Worldwide, six trans boundary aquifers exist with specific agreements, and two aquifers with informal accords. The Northwest Saharan aquifer system that underlies 60 percent of Algeria, almost a third of Libya and part of Tunisia is another trans boundary aquifer with high levels of water withdrawals. It also falls under a cooperation pact and is similar to the Nubian system in that it is non\u2011renewable water. The water is used mainly for agricultural irrigation and industry.<\/p>\n

Projections based on current water usage, anticipated population increase and economic growth scenarios suggest substantial shortfalls in water availability in the coming decade, including nearly 600 aquifers that cross sovereign borders. The depletion of aquifers is the most evident of the Planet\u2019s two groundwater problems, the other problem is groundwater pollution. Pollution diminishes the usefulness of the water that remains after aquifer depletion. The failure to manage Earth\u2019s groundwater resources is a threat to the global stability of human society.<\/p>\n","protected":false},"parent":0,"menu_order":7,"template":"","meta":{"pb_part_invisible":false,"pb_part_invisible_string":""},"contributor":[],"license":[],"class_list":["post-252","part","type-part","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/pressbooks\/v2\/parts\/252","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/pressbooks\/v2\/parts"}],"about":[{"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/wp\/v2\/types\/part"}],"version-history":[{"count":0,"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/pressbooks\/v2\/parts\/252\/revisions"}],"wp:attachment":[{"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/wp\/v2\/media?parent=252"}],"wp:term":[{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/wp\/v2\/contributor?post=252"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/books.gw-project.org\/groundwater-in-our-water-cycle\/wp-json\/wp\/v2\/license?post=252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}