{"id":588,"date":"2018-09-06T10:24:40","date_gmt":"2018-09-06T14:24:40","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/chapter\/7-2-water-supply-problems-and-solutions\/"},"modified":"2024-07-12T17:31:21","modified_gmt":"2024-07-12T21:31:21","slug":"7-2-water-supply-problems-and-solutions","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/chapter\/7-2-water-supply-problems-and-solutions\/","title":{"raw":"6.2 Water Supply Problems and Solutions","rendered":"6.2 Water Supply Problems and Solutions"},"content":{"raw":"

Water Supply Problems: Resource Depletion<\/h2>\r\n

As groundwater is pumped from water wells, there usually is a localized drop in the water table around the\u00a0well called a cone of depression. When there are a large number of wells that have been pumping water for\u00a0a long time, the regional water table can drop significantly. This is called groundwater mining<\/strong>, which\u00a0can force the drilling of deeper, more expensive wells that commonly encounter more saline groundwater.\u00a0Rivers, lakes, and artificial lakes (reservoirs) can also be depleted\u00a0due to overuse. Some large rivers, such as the Colorado in the U.S. and Yellow in China, run dry in some\u00a0years. The case history of the Aral Sea discussed later in this chapter\u00a0involves depletion of a lake. Finally, glaciers are\u00a0being depleted due to accelerated melting associated with global warming over the past century.<\/p>\r\n\r\n

\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"576\"]\"\" Figure 1. Formation of a Cone of Depression around a Pumping Water Well Source: Fayette County Groundwater Conservation District, TX[\/caption]\r\n

Another water resource problem associated with groundwater mining is saltwater intrusion, where\u00a0overpumping of fresh water aquifers near ocean coastlines causes saltwater to enter fresh water zones. The drop of the water table around a\u00a0cone of depression<\/strong> in an unconfined aquifer can change the direction of regional groundwater flow, which could\u00a0send nearby pollution toward the pumping well instead of away from it. Finally, problems of subsidence\u00a0<\/strong>(gradual sinking of the land surface over a large area) and sinkholes<\/strong> (rapid sinking of the land surface over\u00a0a small area) can develop due to a drop in the water table.<\/p>\r\n\r\n<\/div>\r\n

Water Supply Crisis<\/h3>\r\n

The water crisis<\/strong> refers to a global situation where people in many areas lack access to sufficient water, clean water, or both. This section describes the global situation involving water shortages, also called water stress<\/strong>. In general, water stress is greatest in areas with very low precipitation (major deserts), large population density (e.g., India), or both. Future global warming could worsen the water crisis by shifting precipitation patterns away from humid areas and by melting mountain glaciers that recharge rivers downstream. Melting glaciers will also contribute to rising sea level, which will worsen saltwater intrusion in aquifers near ocean coastlines.<\/p>\r\n\r\n

\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"715\"]\"\" Figure 2. Countries Facing Water Stress in 1995 and Projected in 2025 Water stress is defined as having a high percentage of water withdrawal compared to total available water in the area. Source: Philippe Rekacewicz (Le Monde diplomatique), February 2006[\/caption]\r\n

According to a 2006 report by the United Nations Development Programme, 700 million people (11% of the world's population) lived with water stress. Most of them live in the Middle East and North Africa. By 2025, the report projects that more than 3 billion people (about 40% of the world's population) will live in water-stressed\u00a0areas with the large increase coming mainly from China and India. The water crisis will also impact food production and our ability to feed the ever-growing population. We can expect future global tension and even conflict associated with water shortages and pollution. Historic and future areas of water conflict include the Middle East (Euphrates and Tigris River conflict among Turkey, Syria, and Iraq; Jordan River conflict among Israel, Lebanon, Jordan, and the Palestinian territories), Africa (Nile River conflict among Egypt, Ethiopia, and Sudan), Central Asia (Aral Sea conflict among Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan), and south Asia (Ganges River conflict between India and Pakistan).<\/p>\r\n\r\n<\/div>\r\n

Sustainable Solutions to the Water Supply Crisis?<\/h3>\r\n

The current and future water crisis described above requires multiple approaches to extending our fresh\u00a0water supply and moving towards sustainability. Some of the longstanding traditional approaches include\u00a0dams and aqueducts.<\/p>\r\n

Reservoirs<\/strong> that form behind dams in rivers can collect water during wet times and\u00a0store it for use during dry spells. They also can\u00a0be used for urban water supplies. Other benefits of dams and reservoirs are\u00a0hydroelectricity, flood control, and recreation. Some of the drawbacks are evaporative loss of water\u00a0in arid climates, downstream river channel erosion, and impact on the ecosystem including a change from\u00a0a river to lake habitat and interference with migration and spawning of fish.<\/p>\r\n

Aqueducts<\/strong> can move water from\u00a0where it is plentiful to where it is needed. Aqueducts can be controversial and politically\u00a0difficult especially if the water transfer distances are large. One drawback is the water diversion can cause\u00a0drought in the area from where the water is drawn. For example, Owens Lake and Mono Lake in central\u00a0California began to disappear after their river flow was diverted to the Los Angeles aqueduct. Owens Lake\u00a0remains almost completely dry, but Mono Lake has recovered more significantly due to legal intervention.<\/p>\r\n\r\n

\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"333\"]\"\" Figure 3. Hoover Dam, Nevada, U.S. Hoover Dam, Nevada, U.S.. Behind the dam is Lake Mead, the largest reservoir in U.S.. White band reflects the lowered water levels in the reservoir due to drought conditions from 2000 - 2010. Source: Cygnusloop99 at Wikimedia Commons[\/caption]\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"500\"]\"\" Figure 4. The California Aqueduct California Aqueduct in southern California, U.S. Source: David Jordan at en.wikipedia[\/caption]\r\n\r\n<\/div>\r\n
\r\n

One method that can actually increase the amount of fresh water on Earth is desalination<\/strong>, which\u00a0involves removing dissolved salt from seawater or saline groundwater. There are several ways to desalinate\u00a0seawater including boiling, filtration, and electrodialysis. All of these procedures are moderately\u00a0to very expensive and require considerable energy input, making the water produced much more expensive\u00a0than fresh water from conventional sources. In addition, the process creates highly saline wastewater, which\u00a0must be disposed of and creates significant environmental impact. Desalination is most common in the Middle East, where energy from oil is abundant\u00a0but water is scarce.<\/p>\r\n\r\n<\/div>\r\n

Conservation<\/strong> means using less water and using it more efficiently. Around the home, conservation can\u00a0involve both engineered features, such as high-efficiency clothes washers and low-flow showers and toilets, as\u00a0well as behavioral decisions, such as growing native vegetation that require little irrigation in desert climates,\u00a0turning off the water while you brush your teeth, and fixing leaky faucets.<\/p>\r\n

Rainwater harvesting<\/strong>\u00a0involves\u00a0catching and storing rainwater for reuse before it reaches the ground. Another important technique is efficient irrigation, <\/strong>which is extremely\u00a0important because irrigation accounts for a much larger water demand than public water supply. Water\u00a0conservation strategies in agriculture include growing crops in areas where the natural rainfall can support\u00a0them, more efficient irrigation systems such as drip systems that minimize losses due to evaporation, no-till\u00a0farming that reduces evaporative losses by covering the soil, and reusing treated wastewater from sewage\u00a0treatment plants. Recycled wastewater has also been used to recharge aquifers.<\/p>\r\n\r\n

Attribution<\/h4>\r\nEssentials of Environmental Science<\/a>\u00a0by Kamala Dor\u0161ner<\/a> is licensed under CC BY 4.0<\/a>. Modified from the original.","rendered":"

Water Supply Problems: Resource Depletion<\/h2>\n

As groundwater is pumped from water wells, there usually is a localized drop in the water table around the\u00a0well called a cone of depression. When there are a large number of wells that have been pumping water for\u00a0a long time, the regional water table can drop significantly. This is called groundwater mining<\/strong>, which\u00a0can force the drilling of deeper, more expensive wells that commonly encounter more saline groundwater.\u00a0Rivers, lakes, and artificial lakes (reservoirs) can also be depleted\u00a0due to overuse. Some large rivers, such as the Colorado in the U.S. and Yellow in China, run dry in some\u00a0years. The case history of the Aral Sea discussed later in this chapter\u00a0involves depletion of a lake. Finally, glaciers are\u00a0being depleted due to accelerated melting associated with global warming over the past century.<\/p>\n

\n
\"\"
Figure 1. Formation of a Cone of Depression around a Pumping Water Well Source: Fayette County Groundwater Conservation District, TX<\/figcaption><\/figure>\n

Another water resource problem associated with groundwater mining is saltwater intrusion, where\u00a0overpumping of fresh water aquifers near ocean coastlines causes saltwater to enter fresh water zones. The drop of the water table around a\u00a0cone of depression<\/strong> in an unconfined aquifer can change the direction of regional groundwater flow, which could\u00a0send nearby pollution toward the pumping well instead of away from it. Finally, problems of subsidence\u00a0<\/strong>(gradual sinking of the land surface over a large area) and sinkholes<\/strong> (rapid sinking of the land surface over\u00a0a small area) can develop due to a drop in the water table.<\/p>\n<\/div>\n

Water Supply Crisis<\/h3>\n

The water crisis<\/strong> refers to a global situation where people in many areas lack access to sufficient water, clean water, or both. This section describes the global situation involving water shortages, also called water stress<\/strong>. In general, water stress is greatest in areas with very low precipitation (major deserts), large population density (e.g., India), or both. Future global warming could worsen the water crisis by shifting precipitation patterns away from humid areas and by melting mountain glaciers that recharge rivers downstream. Melting glaciers will also contribute to rising sea level, which will worsen saltwater intrusion in aquifers near ocean coastlines.<\/p>\n

\n
\"\"
Figure 2. Countries Facing Water Stress in 1995 and Projected in 2025 Water stress is defined as having a high percentage of water withdrawal compared to total available water in the area. Source: Philippe Rekacewicz (Le Monde diplomatique), February 2006<\/figcaption><\/figure>\n

According to a 2006 report by the United Nations Development Programme, 700 million people (11% of the world’s population) lived with water stress. Most of them live in the Middle East and North Africa. By 2025, the report projects that more than 3 billion people (about 40% of the world’s population) will live in water-stressed\u00a0areas with the large increase coming mainly from China and India. The water crisis will also impact food production and our ability to feed the ever-growing population. We can expect future global tension and even conflict associated with water shortages and pollution. Historic and future areas of water conflict include the Middle East (Euphrates and Tigris River conflict among Turkey, Syria, and Iraq; Jordan River conflict among Israel, Lebanon, Jordan, and the Palestinian territories), Africa (Nile River conflict among Egypt, Ethiopia, and Sudan), Central Asia (Aral Sea conflict among Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan), and south Asia (Ganges River conflict between India and Pakistan).<\/p>\n<\/div>\n

Sustainable Solutions to the Water Supply Crisis?<\/h3>\n

The current and future water crisis described above requires multiple approaches to extending our fresh\u00a0water supply and moving towards sustainability. Some of the longstanding traditional approaches include\u00a0dams and aqueducts.<\/p>\n

Reservoirs<\/strong> that form behind dams in rivers can collect water during wet times and\u00a0store it for use during dry spells. They also can\u00a0be used for urban water supplies. Other benefits of dams and reservoirs are\u00a0hydroelectricity, flood control, and recreation. Some of the drawbacks are evaporative loss of water\u00a0in arid climates, downstream river channel erosion, and impact on the ecosystem including a change from\u00a0a river to lake habitat and interference with migration and spawning of fish.<\/p>\n

Aqueducts<\/strong> can move water from\u00a0where it is plentiful to where it is needed. Aqueducts can be controversial and politically\u00a0difficult especially if the water transfer distances are large. One drawback is the water diversion can cause\u00a0drought in the area from where the water is drawn. For example, Owens Lake and Mono Lake in central\u00a0California began to disappear after their river flow was diverted to the Los Angeles aqueduct. Owens Lake\u00a0remains almost completely dry, but Mono Lake has recovered more significantly due to legal intervention.<\/p>\n

\n
\"\"
Figure 3. Hoover Dam, Nevada, U.S. Hoover Dam, Nevada, U.S.. Behind the dam is Lake Mead, the largest reservoir in U.S.. White band reflects the lowered water levels in the reservoir due to drought conditions from 2000 – 2010. Source: Cygnusloop99 at Wikimedia Commons<\/figcaption><\/figure>\n
\"\"
Figure 4. The California Aqueduct California Aqueduct in southern California, U.S. Source: David Jordan at en.wikipedia<\/figcaption><\/figure>\n<\/div>\n
\n

One method that can actually increase the amount of fresh water on Earth is desalination<\/strong>, which\u00a0involves removing dissolved salt from seawater or saline groundwater. There are several ways to desalinate\u00a0seawater including boiling, filtration, and electrodialysis. All of these procedures are moderately\u00a0to very expensive and require considerable energy input, making the water produced much more expensive\u00a0than fresh water from conventional sources. In addition, the process creates highly saline wastewater, which\u00a0must be disposed of and creates significant environmental impact. Desalination is most common in the Middle East, where energy from oil is abundant\u00a0but water is scarce.<\/p>\n<\/div>\n

Conservation<\/strong> means using less water and using it more efficiently. Around the home, conservation can\u00a0involve both engineered features, such as high-efficiency clothes washers and low-flow showers and toilets, as\u00a0well as behavioral decisions, such as growing native vegetation that require little irrigation in desert climates,\u00a0turning off the water while you brush your teeth, and fixing leaky faucets.<\/p>\n

Rainwater harvesting<\/strong>\u00a0involves\u00a0catching and storing rainwater for reuse before it reaches the ground. Another important technique is efficient irrigation, <\/strong>which is extremely\u00a0important because irrigation accounts for a much larger water demand than public water supply. Water\u00a0conservation strategies in agriculture include growing crops in areas where the natural rainfall can support\u00a0them, more efficient irrigation systems such as drip systems that minimize losses due to evaporation, no-till\u00a0farming that reduces evaporative losses by covering the soil, and reusing treated wastewater from sewage\u00a0treatment plants. Recycled wastewater has also been used to recharge aquifers.<\/p>\n

Attribution<\/h4>\n

Essentials of Environmental Science<\/a>\u00a0by Kamala Dor\u0161ner<\/a> is licensed under CC BY 4.0<\/a>. Modified from the original.<\/p>\n","protected":false},"author":515,"menu_order":2,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[48],"contributor":[],"license":[],"class_list":["post-588","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":586,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/chapters\/588","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/wp\/v2\/users\/515"}],"version-history":[{"count":2,"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/chapters\/588\/revisions"}],"predecessor-version":[{"id":935,"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/chapters\/588\/revisions\/935"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/parts\/586"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/chapters\/588\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/wp\/v2\/media?parent=588"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/pressbooks\/v2\/chapter-type?post=588"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/wp\/v2\/contributor?post=588"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/environmentalissues\/wp-json\/wp\/v2\/license?post=588"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}