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Aquifer storage and recovery (ASR) systems combine man-made technology with existing geological formations and natural weather patterns to store and supply large amounts of freshwater for human consumption. Aquifer storage and recovery systems are a proven technology that efficiently provides freshwater at a fraction of the cost when compared to other types of water storage facilities. This reliable capability possesses the potential to mitigate regional instability by offsetting the effects of drought or providing a source of water in areas of diminishing access to freshwater. ASR systems retain enormous strategic potential by providing a long-term, low-cost source of freshwater to developing and agriculturally dependent nations.
R. David G. Pyne defines aquifer storage and recovery systems as “the storage of water in a suitable aquifer through a well during times when water is available, and recovery of the water from the same well during times when it is needed.” Essentially, excess or abundant freshwater is pumped into an aquifer, stored, and recovered when needed using the same pump. Instead of only extracting water, ASR systems replenish or expand existing aquifers or create new aquifers. Aquifer storage and recovery systems have twenty-two uses, but seasonal storage, long-term storage, and emergency storage of freshwater comprise the three primary applications.
Aquifer storage and recovery systems have been in use worldwide for over 40 years. The United States contains the majority of the ASR systems employed globally. Other countries such as Australia, Israel, India, and England use ASR systems to provide an available source of freshwater. Pakistan is studying the feasibility of using ASR systems to mitigate current water shortages.
The Strategic Value of Freshwater
The strategic value of freshwater should not be underestimated. In a speech given at the National Geographic Society on March 22, 2010, Secretary of State Hillary Clinton remarked that access to clean freshwater is a matter of national security. Since 805 AD, over 3600 non-navigational freshwater treaties have been signed, including 300 treaties signed since 1945. The increasing scarcity of accessible sources of uncontaminated freshwater exacerbates local and regional instability. Dr. Peter Gleik recorded over 40 cases of major violence due to constrained access to freshwater between 2000 and 2009. Examples in Kenya demonstrate the range and magnitude of violence. Between September 2009 and September 2010, an estimated 400 people died due to clashes over access to water. In another conflict, a clash between villagers and monkeys left eight monkeys dead and 10 villagers wounded.
According to Nevin Kresic, 36% (18 million mi2) of available dry land depends on groundwater for irrigation. Freshwater in lakes, rivers, and groundwater comprises 0.609% of the total global supply of freshwater. The global supply of groundwater totals 0.6%. Almulla et al contend only .008% of the global supply of freshwater is available for human use. The remaining 99% supply of freshwater is locked up in ice and the oceans.
Scarcity of Freshwater
By 2025, 40 countries in the Middle East and Africa will have scarce supplies of freshwater. According to the United Nations fact sheet on water and sanitation, 1.1 billion people currently lack access to uncontaminated drinking water. Pakistan is facing a water crisis. Irrigation consumes over 90% of available water, and available water has declined over 66% since the 1950s. Niger and Mauritania are nearly dependent on external supplies of water.
Groundwater comprises the main source of freshwater in Africa. Groundwater supplies 95% of Libya’s freshwater. Due to increasing populations and an increased demand for agriculture products, many African countries overexploit sources of freshwater through poor irrigation practices. This depletes existing aquifers and may deteriorate the quality of the remaining freshwater. Drought in Nigeria between 1985 and 1989 led to the drilling of 537 wells, many of which were left uncapped and free flowing. Large quantities of water were lost and added to the decreasing water level of Lake Chad. Subsequently, the water level at Lake Chad has declined more than 80% since 1980.
Most Gulf Cooperation Council countries in the Middle East (United Arab Emirates, Qatar, Kuwait, Bahrain, Oman, and Saudi Arabia) have less than a four day supply of freshwater stored for use. The United Arab Emirates is constructing a $435 million facility to store up to a 90 day supply of freshwater (over six billion gallons) for Abu Dhabi City in the event of an emergency. Water consumption in Kuwait is almost equal to the production capacity of desalination plants. In Kuwait, irrigation of landscaping led to declines in groundwater forcing residents to shift to freshwater produced from desalination plants.
Advantages of Aquifer Storage and Recovery Systems
ASR systems have advantages when compared to other types of water storage facilities. Some of the advantages are: large storage capacities, low construction costs, require an acre or two of land per well (i.e. small footprint), low risk of contamination, safe from vandalism, and no evaporation loss. Additionally, ASR systems offer the flexibility to expand for increased storage capacity. A community could install a small ASR system and expand the system as the community grows.
Storage capacities of ASR systems range from 10 million gallons to billions of gallons of water. Many ASR systems in the Southeast United States inject water into the Floridian aquifer which covers hundreds of thousands of square miles. The Las Vegas, NV ASR system combines the advantages of a large freshwater storage capacity and a small footprint compared to a comparable reservoir. The Las Vegas ASR system comprises 42 wells with a 157 million gallon per day (MGD) capacity. At an acre or two of land per well, the land requirement is a fraction of the amount needed for a reservoir of comparable storage capacity. An above ground 100 MGD facility would require a reservoir one KM wide by 12 KM long by 10 meters deep.
Many studies document the financial advantages of constructing and operating an ASR system versus other water storage facilities to store and provide freshwater. Myrtle Beach, SC analyzed the annual cost of producing and storing 1000 gallons of freshwater between different storage facilities as shown in Table 1.
Table 1: Annual cost to produce and store 1000 gallons of freshwater
Construction costs of ASR systems vary widely due to the size of the system required for the intended purpose. West Palm Beach, FL spent $1,700,000 on an ASR system that currently injects up to eight million gallons per day for storage. In Ft. Myers, Florida an ASR well that supplied one million gallons of freshwater per day was estimated at $1.5 million. Tualatin, Oregon built a $2.4 million ASR system that will supply one million gallons of freshwater for 90 days. San Antonio, TX constructed a $240 million ASR system to store up to 21.3 billion gallons of freshwater. Three years after completion, the ASR system injected 10.2 billion gallons of excess freshwater. In comparison, the Temperance Flat dam in California is estimated to cost $3.3 billion and may provide less than 65 billion gallons of water annually. Table two provides a sample of the different ASR systems in the United States.
Table 2: Comparisons of different ASR systems in the United States
Farmers employ aquifer storage and recovery systems to provide freshwater to mitigate the effects of dry seasons and drought. Farmers in eastern Oregon take advantage of the wet winters and employ ASR systems to pump excess water into aquifers to offset the effects of dry summer months. Orissa, India’s monsoon season (June through September) produces 82% of the annual rainfall. Capturing excess rain water and storing it in ASR systems permitted an additional harvest during the dry winter season. Doug Wilson concluded that a 1.5 billion gallon ASR system in southwest Georgia would have a positive effect on the agricultural economy by mitigating drought conditions for one to two years. Brigham City, Utah uses ASR systems to offset the dry summer months with very low cost. Portugal is seeking ASR systems to mitigate the effects of drought in southern Portugal where groundwater supplies freshwater. ASR systems dampen the effects of drought in Australia.
Aquifer storage and recovery systems take advantage of different sources of untreated freshwater in order to fill aquifers for future irrigation use. Some of those sources of water are municipal wastewater, storm water runoff and irrigation return flow. Using nonpotable water for irrigation reduces demands on freshwater sources. Adelaide, Australia employs 22 ASR systems to annually inject and store 528,400,000 gallons of storm water runoff which is used primarily for irrigation. The San Antonio, TX ASR system benefited from heavy rains to pump water into its underground aquifer.
Drawbacks of Aquifer Storage and Recovery Systems
Aquifer storage and recovery systems develop problems when not constructed correctly. The wells can clog preventing the injection or recovery of water. Hazardous trace elements such as arsenic may leech into the aquifer. ASR systems require specific geological conditions to successfully store and extract water, thus poor planning or employing unqualified engineers may cause the stored water to flow out of the aquifer.
Successful construction of an aquifer storage and recovery system requires patience and time. The St. Johns River Water Management District in Florida experienced a 3½ to 5½ year process to construct a complete and operational ASR system from site selection to final construction. Actual construction of the ASR system itself may take from 12 to 18 months. Constructing an ASR requires a long-term commitment to ensure the system operates properly and stored water remains uncontaminated. A correctly constructed and properly operating ASR system provides local communities a long-term source of freshwater to mitigate drought or reduce the incidents of water-borne diseases.
Aquifer storage and recovery systems have the potential to reduce tensions between nations or populations that compete for freshwater from the same source. Capturing and storing excess freshwater in aquifers precludes constructing dams or reservoirs on rivers that may violate international treaties. In 2008, a group of Iranians crossed the Afghanistan border and bulldozed a diversion dam built on the Helmand River. Pakistan and India are in talks over concerns of India’s usage of the Indus River.
Providing a sustainable source of uncontaminated freshwater for human consumption or irrigation in Afghanistan utilizing ASR technology would benefit Afghans. Only 20% of Afghans have access to clean, uncontaminated water which contributes to health problems. Seventy-five percent of the 400 patients at the Parwan provincial hospital suffer from diseases due to ingesting contaminated water. In Charikar, Afghanistan, the lack of access to clean water exacerbates the tension between Afghans and the NATO coalition. A promise of clean water remains unfulfilled as a $1.25 million, four-well project has been delayed. In the Khost province of Afghanistan, the construction of wells and dams by well-meaning military and non-governmental organizations lowered water tables and dried up traditional sources of water. Provincial reconstruction teams constructed diversion dams on the Shamal River, but the reservoirs filled up with silt after just two years.
In Afghanistan, 85% of the residents farm for a living. Due to unreliable patterns of rainfall, 85% percent of Afghanistan’s agriculture products depend on irrigation. For years, Afghan farmers relied on an ancient system to irrigate crops. These ancient systems, called karez, are horizontal tunnels dug into the base of mountains. In 2002, 6,741 karez systems irrigated 163,000 hectares. By 2008, over 60% of the karez systems dried up due to drought conditions. Because of drought, the amount of irrigated farmland declined by 50%. This statistic is critical as agricultural products cannot grow in irrigation-dependent areas due to unreliable rainfall. As a result, rain-dependent agricultural areas have contracted due to successive dry years. In addition, spring melt water from glaciers and snowpack arrives earlier in the year due to changes in climate. This results in less available water to irrigate crops in late summer. ASR systems could potentially store the excess freshwater available during snow melt and excess precipitation then extract the water during the dryer months to irrigate crops and provide potable water to Afghan villages and cities.
Hope exists for water issues in Afghanistan. John Shroder of the Afghanistan Studies Center at the University of Nebraska at Omaha states that there is plenty of water available, especially sources of groundwater. Accessing sources of groundwater and using it wisely is critical to the sustainability of agriculture and crucial to the stability of Afghanistan. ASR systems could take advantage of any existing aquifers in order to store excess water.
Currently, the U.S. Army Corps of Engineers is the only Department of Defense entity utilizing ASR technology. The United States military contains over two dozen well drilling units that are tasked to provide potable water to military units. The well-drilling manual used by the Air Force, Navy, and Army does not mention ASR systems. Well drilling units possess the drilling equipment necessary to reach adequate depths for an ASR system. If the U.S. military adopted ASR construction well drilling units would require additional training to properly construct an ASR system. Possessing this type of proven, non-lethal technology is a capability that can assist a commander’s ability to proactively respond to inherent instability caused by constrained access to freshwater.
Aquifer storage and recovery systems are a proven technology that captures excess freshwater from various sources, stores the freshwater in aquifers, and then recovers the freshwater when needed. The benefits of ASR systems outweigh other freshwater storage systems. ASR systems are less expensive to construct than dams and reservoirs, provide flexibility in that ASR systems can expand to meet growing needs, have a small surface footprint, and can store large amounts of water with no loss to evaporation. Aquifer storage and recovery systems could be a potential diplomatic tool and assist with local and regional stability to arid regions of the world by providing a sustainable source of freshwater for agricultural and personal use.