Sustaining Water Resources: A Global Imperative - ACS Publications

Chapter 19

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Sustaining Water Resources: A Global Imperative Hessy L. Taft* Department of Chemistry, St John’s University, Queens, New York, New York, 11439 *E-mail: [email protected].

Global freshwater is finite and its supply is being severely strained by competing forces of an expanding world population and alterations in the water cycle as a result of climate change. A range of regional concerns regarding freshwater use has been identified and these must be addressed to maintain the sustainability of our precious water resources. Rigorous conservation methods must be instituted including agricultural use, domestic use, electric power generation and related emerging energy technologies. Innovative technologies such as water reuse, desalination, and additional water storage infrastructure to replenish groundwater supplies are effective measures to augment world water supplies. Yet water is unevenly distributed globally, leaving many regions deprived of a safe water supply. As demands for water intensify, regional integration will provide benefits of enhanced security of water supply, improved public health, more reliable food supply, and better economic efficiency.

Introduction Freshwater scarcity is a global reality. Multiple competing forces are draining this precious resource. One driving force is the increasing demand for freshwater. The world’s population is experiencing exponential growth and is predicted to reach 9 billion people by 2050. This implies not only a circa 30% increase over current levels for drinking and sanitation needs. There will also be a concomitant demand for increased global agricultural production in order to © 2015 American Chemical Society In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


meet food requirements for the growing population. In most areas of the world, agriculture is the largest consumer of freshwater. The uneven distribution of water worldwide further limits equitable access to freshwater to many regions where it is critically needed. At the start of the 21st century, about 1.1 billion people lacked access to safe drinking water and about 2.5 billion people lacked adequate sanitation. About 2 million people, of whom approximately 80% are children, die each year from water borne diseases. Furthermore, large quantities of water are required for energy production and generation. In 2009, the World Economic Forum (WEF) published a report pointing out that the energy sector consumes on average about 40% of the total national water supply in developed countries, yet merely 8% of the total water use in developing countries (1). Long-term economic development and industrialization in the developing countries will place greater stress on water supplies to support demands for food security, human health and energy consumption. As the socioeconomic status of poorer world populations attain middle class status, demands for freshwater will continue to escalate drastically, particularly for the agricultural and energy sectors of society. A factor limiting the potential for meeting global freshwater needs is the dwindling supply of available freshwater. The reduced levels of surface water in many regions results primarily from climate change but mismanagement and overexploitation of existing resources put additional strain on freshwater supplies. Meeting the future demands for freshwater will require nations to cooperate in the implementation of a wide array of approaches, including innovation, conservation, infrastructure management, and regulation, in order to achieve the delicate balance between growing demands for agriculture, domestic uses, energy production, sanitation and public health. This paper discusses these approaches and describes specific available technologies - involving low or high capital investment strategies - that can accommodate the competing demands made on water on a global scale. Since many of the most sophisticated advances for coping with water shortages have been developed in the United States and Israel, their contributions feature prominently herein.

Impact from Climate Change As can be seen from Figure 1, the Earth’s temperatures both on land and oceans have increased dramatically in the last 30 years. The major culprit for this phenomenon is the sharp increase of CO2 in the atmosphere which traps heat by absorbing incoming infrared radiation. It is estimated that around 1800, shortly after the beginning of the industrial revolution, the level of atmospheric CO2 was 284 ppm; it was about 311 ppm shortly after World War II and reach about 385 ppm in 2008 (2). While CO2 is responsible for 82% of total greenhouse gas emissions in the United States, CH4 and N2O contribute 10% and 5% respectively to the total emissions. CH4 is a far more potent heat trapping gas than CO2 but, unlike CO2, it has a short lifetime of 12-year retention in the atmosphere (3). 414 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Figure 1. Land and ocean temperature changes since 1880. Source: Figure courtesy of NASA.

A warmer atmosphere retains more moisture and releases more kinetic energy during precipitation which in turn leads to more violent storms, more flooding in wet areas, more sediment erosion and run-off that eventually flow to the sea. The oceans consist of 71% of Earth’s surface but receive 80% of all precipitation, thus representing a net loss of freshwater for replenishing aquifers. Warmer oceans are less dense, causing expansions of oceans and a rise in sea level, for which the observed global rate has been circa 3mm/year since 1992. This in turn causes the salinization of coastal freshwater deltas and wetlands. Salt accumulation in topsoil has destroyed farmlands. The salt environment has allowed invasive species to establish new habitats. The Yellow River in China is a prime example affected by this phenomenon (4). In the Arctic, thick multi-year ice caps covered with fresh snow could reflect up to 85-90% of incoming solar radiation. With warmer temperatures, melting has left only thin young ice surrounded by water melt ponds. Its reflection rate of sunlight is just 37% and more solar radiation penetrates the ocean. As more heat is absorbed by the young ice, melting is accelerated, further warming the planet (5). Globally, the melting of mountain snow caps prior to the growing season for crops represents a significant loss of fresh water storage vital for agriculture. Erratic flooding patterns increase the severity of droughts, promoting crop failures. Farmers are provoked to intensify over-pumping of aquifers to mitigate crop losses. Indeed, the intensity of drought in wide ranging areas of the world is so severe that restrictions to water supplies are increasingly felt in the domestic sector as well as the agricultural sector, as illustrated by the following examples. 415 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


In 2015, as a result of four consecutive years of drought, California mandated restrictions on water used in every community throughout the state. The magnitude of restrictions is dependent on existing consumption and penalties apply for noncompliance. This kind of conservation measure is relatively new in California where the culture of plentiful resources prevails. Yet concerns have been expressed that wealthy residents may prefer to pay penalties rather than adapt to much needed conservation measures. Drought conditions are seen throughout the southwestern US. In states like Arizona, New Mexico, and Texas, where warm temperatures have spurred evaporation, reservoirs are reduced to record lows. In Pakistan, major water losses are incurred in agriculture, the country’s main economic activity, which employs about 45% of the population and accounts for 21.8% of gross domestic product. Water availability is dependent principally on the flows of the Indus River which originates in the Himalayas. Supply is being increasingly limited by decreasing rainfall and melting of mountain snow caps as a consequence of climate change. Furthermore, the problems are being seriously exacerbated by chronic mismanagement of its extensive network of canals, designed to provide gravitational irrigation. In fact, the deteriorating and leaking canals contribute to over 50% of water loss before reaching any crop. Pakistan has poor water storage facilities with only 9% of its water stored in reservoirs. Hydropower is unreliable and the failing electricity infrastructure in the north causes frequent blackouts of several hours at a time, even in major cities (6). Even in Brazil, a country which boasts 12.5% of the world’s freshwater and has an extensive array of dams, its largest and wealthiest city is experiencing the effects of drought. Sao Paulo, a metropolis of circa 20 million inhabitants, is finding that water is being delivered to residents at reduced pressure, in an effort to avert actual water rationing. Multiple causes contribute to the crisis: destruction of surrounding forests and wetlands has reduced their inherent ability to absorb rain and release it to the reservoirs; the pollution of the two rivers that traverse the city is so severe that the stench is palpable; and deforestation in the Amazon basin, hundreds of miles away, may also contribute to reduced capacity to release moisture and lower the rainfall in the southeast of the country. But just as problematic is the chronically leaky distribution system where huge amounts of water are spilled before reaching homes. Coupled with the burgeoning population growth of the city, residents are already feeling the pinch of limited water availability. The water company has indicated that it has already embarked on construction of new reservoirs that will draw water from a nearby river basin but it is not intended to become operational for at least another year (7). The UN Intergovernmental Panel on Climate Change published its first comprehensive report delineating in detail the severity of the problem regarding greenhouse gas emissions in 2007 and they have since published further reports providing updates to the problem (8). There is growing recognition by an increasing number of nations that the crisis of water and food security posed by climate change requires practical and large-scale solutions. The International Energy Agency has reported that many nations have lowered carbon emissions with more fuel efficient vehicles, promoted energy efficient devices and are subsidizing the renewable energy sector (9). 416 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Sustaining Freshwater Availability in Agriculture Long periods of drought such as those exhibited in India and the southwestern United States in the last decade for example, are prompting the pumping of aquifers below their natural replenishment level, a practice that is clearly not sustainable (10). Agriculture consumes circa 70% of the world’s freshwater, both rainfed and irrigated, but is also a leading polluter by virtue of the run-off from fertilizers and pesticides. Farms using sprinklers in semi-arid environments lose considerable water to evaporation. Leaks in canals built for irrigation are evident worldwide and account for glaring wastes of our valuable water resource. Poor management policies in many parts of both the developing and developed world, lack of regulated oversight, poor maintenance of existing facilities, and diversion of water for crop biofuels, all contribute to inefficient agricultural practices. Such conditions endanger food security. Fortunately, some successful remedies have been developed. The method of drip irrigation, invented in Israel about 50 years ago, has now been implemented in over 30 countries worldwide. Drip irrigation entails a direct “drop to crop” application of water to plant surfaces or roots by means of long tubes with punctured holes through which the water reaches the plant. In addition to the obvious water savings incurred, this irrigation technique, greatly reduces erosion, and increases productivity. It also reduces labor requirements and does not require any heavy capital investment. Figure 2 shows the initial and mature stages for growing almond trees via drip irrigation in the Central Valley of California, which produces 80% of the world’s almonds. This practice is a typical example of virtual water trade, where a commodity being exported saves the importing country from the need for its own water allocations. Exporting virtual water in times of drought has been questioned as a dubious practice, but such reservations can be alleviated by using water efficient drip irrigation to produce high product yields.

Figure 2. Cultivation of almond trees via drip irrigation in the Central Valley, California. Source: Courtesy of Netafim USA, 2015. 417 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

Rice is a grain that supplies the caloric intake of approximately 70% of the world’s population. In Asia, approximately 50% of available water is used for growing rice. The leading rice producing countries are shown in Table 1.

Table 1. World’s Largest Rice Producers, 2013


Country

Quantity (million metric tons)

China

205

India

159

Indonesia

71

Bangladesh

51

Vietnam

44

Thailand

37

Myanmar

29

Philippines

18

Brazil

12

Source: Courtesy of FAOSTAT from reference (11).

Figure 3. Rice farm cultivated via flood irrigation in India. Original Source: www.rkmp.co.in (Developed by Directorate of Rice Research, Indian Council of Agricultural Research), India. 418 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


However, due to water shortages, some countries, such as Thailand, are reducing their level of rice cultivation. Figure 3 illustrates a rice farm cultivated via flood irrigation in India and Figure 4 depicts a rice farm using drip irrigation, also in India. The contrast in water consumption is striking. Flooded irrigation in India consumes about 15,000 liters of water to produce 1 kilogram of rice (12).

Figure 4. Rice farm using drip irrigation in India. Source: Courtesy of REUTERS/Amir Cohen. The vast amounts of water consumed in flooded rice fields are not contributing to productive yields and thus constitute inefficiency and waste of an increasingly scarcer valuable resource. This is particularly serious since flooded rice fields produce significant quantities of methane and nitrous oxide emissions, which contribute to the total global greenhouse gas emissions. These powerful greenhouse gases exacerbate the trapping of infrared radiation in the atmosphere. The Indo Israel Cooperation Project which started in 2008 is planning a total of 29 agricultural centers, 15 of which are already operational, that provide training, demonstrations of waste water treatment, and water management. Each center impacts about 10,000 farmers (13). In Israel, the water delivered by drip irrigation contains essential nutrients needed for plant growth. Thus no additional fertilizer is required, representing considerable savings for farmers. Furthermore, Israel takes additional steps to maximize the efficiency of water applied to crops. Electronic sensors that transmit remotely-sensed images and data monitor soil moisture and stem diameter, provide a mapping of mineral and water stress, and above all check for irrigation failures. In addition, many large farms in Israel are covered with transparent plastic sheets or fine mesh coverings in order to control evaporation, conserve heat and control insect infestation. These are conservation measures, all geared to optimize water use. 419 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Scarcity of water has prompted new techniques that rely on water reuse for irrigated agriculture in several countries. Since approximately 90% of the developing world has no wastewater facility, the reuse of raw sewage for agriculture is common and the associated public health problems loom large. Chemically enhanced primary treatment (CEPT) is a relatively effective method to remove active pathogens from raw sewage. It still leaves essential nutrients of nitrogen and phosphorus in the effluent, mitigating use of additional fertilizers. In 2009, the CEPT technology was initiated to purify raw sewage in Mexico City, the second largest metropolitan area in the Americas, for reuse in irrigated agriculture. The total suspended solids removed were 70-75% and the total COD removal ranged between 30-36%. This would allow for additional effective chlorination or use of UV treatment with medium pressure mercury lamps if such techniques were desirable and economically feasible (14). However, the count for helminth eggs in the water treated with CEPT remained consistently at 1-5 eggs/liter, a value that does not meet existing WHO guidelines (15). In Israel, wastewater treatment for irrigated agriculture has been in use since 1977. By the mid 1980s, the Tel Aviv metropolitan wastewater system recycled 100% of the water used by its more than 2 million inhabitants. Known as the soil aquifer treatment (SAT), it subjects effluent exiting a wastewater treatment plant (WWT) to secondary and tertiary purification. The effluent is pumped from clarifiers at the end of WWT to recharge basins where the water undergoes gravitational filtration into an aquifer below. The loading of the recharge basins is done by intermittent periods of flooding and drying, to allow for additional disinfection with oxygen, a process that destroys microbial pathogens. As the water penetrates the deeper anaerobic layers of the aquifer, the water undergoes further organic matter degradation and adsorption, precipitation, NH3 adsorption, and biological nitrification and denitrification. The water is deliberately retained in the aquifer for a 300 day period before it is withdrawn for use, thus facilitating inactivation of microbial pathogens in anaerobic conditions. Before the water is withdrawn it is tested by observation wells to monitor purification efficiency after which is removed by recovery wells and pumped, via pipelines up to 100 kilometers long, to reservoirs in the Negev desert for use in agriculture. This SAT process provides a removal efficiency of 100% suspended solids, 98% BOD, 85% COD, 99% total phosphorus, 57% total nitrogen and 98% detergents. These local reservoirs provide both seasonal and multi-year storage of high quality water for irrigation that requires no additional fertilizers and is independent of drought (16, 17). But the SAT process has had some problems in recent years. As the population of Tel Aviv has increased, the larger volume of effluent has led to shorter drying periods for infiltration into the recharge basins which reduce the disinfection period. Alternatively, lower volumes of water are subjected to recycling. More problematic is the discovery of concentrations of manganese between 2-40 micromol/L in the reclaimed effluent whereas the Israeli allowed maximum for irrigation is 3.6 micromol/L. The problem has been identified as arising in the SAT system itself. Oxidation of organic matter in the anaerobic infiltration into the aquifer causes the reduction of insoluble Mn oxides in rock to dissolve into the soluble Mn2+ (18). Currently, this problem is being addressed by dilution with harvested rainfall or desalinated water. 420 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


By far the most extensive reclamation from sewage water worldwide is being carried out in Orange County, California at their Groundwater Replenishing System (GWRS) which recycles water to the potable level by including a quaternary treatment in its purification system. Water exiting from the standard sewage purification plant in Orange County is sent to GWRS for additional processing: microfiltration, reverse osmosis, and finally UV irradiation and hydrogen peroxide treatment. The last step, advanced oxidation process, removes trace organic compounds and the UV radiation kills pathogens by destroying thymine in DNA. The resulting water is highly pure. One half of the 132,000 m3/day is pumped to the coast to form a hydraulic barrier which prevents sea water from intrusion into groundwater. The other half of the pure water is sent to a percolation pool to seep into permeable soil to deep aquifers, thereby replenishing the groundwater table (19, 20). This process is very costly but it is a source of potable water that meets 10% of the needs of the approximately 2.5 million residents. Since the oceans comprise 97% of the world’s water, it seems logical to turn to this abundant source for boosting our much needed freshwater supply. The process entails desalinating sea water which requires extensive input of energy and leads to significant economic costs for both construction and maintenance. The brine disposal arising from this process can produce serious environmental impacts on marine life. Nevertheless, desalination is proceeding at accelerated rates worldwide due to the escalating scarcity of available freshwater. China, which opened a thermal desalination plant in Tianjin in 2010 adjacent to a power plant, produces 200,000m3 per day. The facility is powered by waste heat generated by Tianjin electricity. China has also embarked on rapid development of new reverse osmosis plants so that it produced 0.9 million cubic meters/day in 2009 and has set ambitious targets to become a key desalination player on the world stage, like Saudi Arabia and Israel (21). Desalination promises to achieve a long term remedy to sustainability of our critical water resource. Thus limitations arising from this process are being comprehensibly addressed. Table 2 shows the costs associated with selected desalination facilities of varying production capabilities (22). The energy consumption for seawater desalination typically operates at 3-4kWh/m3 water produced. Based on thermodynamic principles, the theoretical minimum of energy needed for reverse osmosis of seawater must be such that the applied pressure of the feed equals the osmotic pressure of the concentrate. Current plants are operating at 10-20% higher energy (23). In reverse osmosis, a large part of this energy is required for pre-treatment to protect the delicate membranes from biofouling. This is accomplished by disinfection with a hypochlorite and subsequent coagulation where sludge collects at the floating surface. The reverse osmosis itself sends pressurized seawater through semi-permeable membranes for salt removal. Efforts to improve membranes to minimize biofouling cannot compromise water flux or salt rejection. For example, use of oxidizing agents would break amide linkages in the polyamide membranes so such chemicals cannot be used. Some desalination plants are set up so turbines can recover additional seawater before brine rejection. In any case, the treated seawater has a low pH which increases the risk of corrosion in the distribution pipes and lacks 421 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

the minerals necessary for maintain normal plant growth in agriculture. In Israel, desalinated water is remineralized with lime filters before it is used as irrigation water thereby eliminating the need to additional fertilizers. This constitutes an enormous positive economic benefit for farmers.

Table 2. Cost Efficiency of Selected Desalination Facilities Production Mm3/yr

Cost $US/m3

Lymassol, Cyprus

13

1.18

Hamma, Algeria

66

0.82

Larnaca, Cyprus

18

0.76

Perth, Australia

46

0.75

Skikda, Algeria

33

0.73

Point Lisas, Trinidad

39

0.70

Tampa Bay, Florida

31

0.67

Hadera, Israel

127

0.60

Tenes, Algeria

66

0.59

Palmachim, Israel

30

0.55

Mactaa, Algeria

165

0.55

Sorek, Israel

150

0.53

Ashkelon, Israel

108

0.52


Desalination Facility

Source: Adapted with permission from reference (22): “Sea water desalination in Israel: planning ,coping with difficulties, and economic aspects of long-term risks”, A Tenne, Water Authority, State of Israel, Desalination Division, 2010.

Brine disposal is another issue that must be adequately addressed in order to avoid serious environmental damage. Just dumping the brine off the coast would, in short order, destroy marine life at the continental shelf. Some approaches have proposed sending the brine down long pipelines to the lower ocean where it would remain because of its higher density. Still, such a procedure would decimate the marine life in the lower ocean. The most reasonable proposal involves shipping the brine off shore several miles from the coastline, thereby avoiding the habitats of most marine life, and releasing the brine as a spray in order to facilitate rapid dilution. The desalination of seawater is limited to coastlines. For areas inland, where extensive pumping of groundwater has taken place, the water reaching the surface is brackish. Thus desalination of brackish water for agriculture becomes necessary. However, because brackish water is not as salty as seawater, 422 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


desalination can be operated at lower energy and pressure. Typically, an energy requirement of 1.37kWh/m3 is sufficient but the extensive pre-treatment that is carried out for seawater desalination is applicable here. This involves sand and micro filtration, and active carbon filtration. In Israel, desert desalination uses nanofiltration membranes that have lower selectivity but retain essential minerals such as Ca2+, Mg 2+, SO42- and HCO3-, needed for healthy plant growth. Typically the Cl- in these permeates is 120ppm. Figure 5 shows a desalination facility of brackish water in the Negev desert of Israel.

Figure 5. Desalination of brackish water in the Negev desert, Israel. Source: Courtesy of Daniel Sokow, American Associates of Ben-Gurion University.

In Israel, overall desalination of brackish water has steadily increased from 18.4 million cubic meters/year in 2009 to 63.2 million cubic meters/year in 2013 (22). Viable yields of grains, such as corn and millet, have been grown in the desert. However, brine disposal from brackish water desalination presents different challenges from sea water brine disposal. Transporting brine to a seacoast is prohibitively expensive and not realistic. Because brine from brackish water desalination in far less concentrated than that from sea water, other uses have fortunately been found. Beets are a salt tolerant crop that grows well in this medium (24). 423 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

Water and Energy: Mutual Dependence


As is evident from the discussion above, sustaining and boosting global water resources to meet the demands of human subsistence and maintain environmental viability require significant input from the energy sector. In the US, recent research indicates that the complete water sector consumes more than 12% of national energy produced (25). This includes energy for pumping from aquifers, water purifying and distribution, heating and chilling, wastewater treatment (WWT), and desalinating both sea water and brackish water. Figure 6 captures the close association of water with various energy sectors.

Figure 6. Interdependency of water and energy sectors. Source: Courtesy of Sandia and Los Alamos National Laboratories. In the US, water reclamation and desalination are growing annually at 15% and 10% respectively and these processes require two to five times more energy per unit of water produced than traditional water treatment technologies. One example is high energy use of ultraviolet light (UV) which is useful for killing microbial pathogens in reclaimed water by inhibiting the thymine synthesis in DNA. It also eliminates the undesired by-products associated with traditional chlorination. Emerging technologies for addressing water contaminants arising from endocrine disruptors and pharmaceutical and personal care products in treated water will require additional high energy input. Yet the burgeoning demand for energy is also placing alarming demands on the water sector. In 2012, a study by the International Energy Agency estimated that world energy demand would grow by 30% by 2035 whereas energy generation and production would require an increase of 85% water consumption (26). Traditional uses of massive amounts of water in energy production, such as the cooling of pipes heated during power plant operation, are being replaced by technologies such as thermoelectric cooling (dry cooling) which require little water. Likewise, certain renewable energies, such as wind and solar photovoltaics, require little 424 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


water but their applications are limited because of intermittent availability and high costs. But other renewable energy technologies, such as biofuels that emit lower greenhouse gases, are not necessarily economical of water use (27). Typically, irrigated biofuels consume as much as 1000 times more water than traditional oil-based fuel production. While ethanol derived from crops reduces the use of petroleum-based fuel for transportation, the planting of irrigated crops for biofuels is ill conceived since this approach diverts land and water sorely needed for feeding the world’s expanding population. The most extravagant use of water for energy is consumed in the relatively new process of hydraulic fracturing, during which millions of gallons of water are mixed with sand and various chemicals for pumping deep into shale rock in order to release natural gas trapped therein. Oil and gas companies are using brackish water and water reuse for this process in an effort to preserve limited freshwater. Natural gas is a cleaner fossil fuel than petroleum and could make the countries that mine it energy independent but the water exiting from the process is far more saline than sea water and is currently sent for burial deep underground. The potential effect on groundwater is as yet unknown. The technology generating hydroelectric power is a clean form of energy that has been tapped worldwide. Hydropower does not contribute to climate change because it does not involve emissions of greenhouse gases.

Addressing Energy and Agricultural Needs: Dams and Reservoirs For centuries, ancient civilizations were adept at building a system of dams to harness river water so as to protect adjacent farms from flooding. In 256 BC, extensive dikes and channels were built in China’s western Chendu Plain in order to divert water from the Min River and provide a reliable source of water for rice irrigation. Today, in Israel, the national water company Mekorot, is doing essentially the same thing. Most of the rain in Israel falls in the northern part of the country and severe storms can occur in the winter months between November and March. Mekorot has built storm water catchment facilities at two locations: 1) at the Menashe River plant which drains flows from the river to diversion channels that infiltrate the sands of Ceasarea and replenish the aquifer below; 2) at the Shiqma River plant where the collection of flood waters is introduced directly into the southern aquifer below. In an average year, 25 million cubic meters of water are collected by this process which proceeds by gravity infiltration and requires no energy input. Figure 7 illustrates a storm water catchment facility installed by Mekorot (28). In the 20th century, advanced engineering techniques made it possible to construct massive concrete dams worldwide. The stored water serves both as a means for producing electricity and as a source of irrigation water as well. The Danube River basin, which flows through 17 countries in Europe, has been fragmented by numerous dams. The La Plata River basin in South America has more than 40 dams built and proposed along its path. The Nurek Dam in Tajikistan, the tallest worldwide, generates and sells electricity to neighboring 425 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


countries. In the process, the dam deprives Uzbekistan of much needed water for growing cotton, a thirsty crop but important export product. But the most gigantic of all dams is the Three Gorges Dam which spans the Yangtze River in China. It measures 2.3 kilometers across, holds 39.3 billion cubic meters of water, and can generate 84.7 billion cubic meters of electricity per year. It has controlled destructive flooding so agriculture is stable on the banks of the Yangtze. Thus it appears that both agricultural and energy needs for the region have been met. But they have been attained at the expense of an upheaval of the surrounding ecosystem. The thick sediment the Yangtze River carries is trapped behind the dam, reducing its efficiency and leading to erosion at the lower end of the dam. This has encouraged salinization of the wetlands at the mouth of the river which in turn has led to invasive species that thrive in an environment where they have no predators. Furthermore, species upstream, such as the dolphin and sturgeon, have also been affected by being unable to reach their breeding grounds. As a result, their populations have been declining (29, 30). The Chinese government has adopted several measures to counteract these environmental challenges but so far have had only very limited success.

Figure 7. Storm water catchment facility, Israel. Source: Reproduced with permission from reference (28), Mekorot, Israel, 2015.

Since electricity is an essential commodity for the well being of modern society, dams that generate clean energy play a critical role. However, adverse impacts incurred by insufficient oversight and negligent management must be avoided. Table 3 shows the per capita electricity consumption in various countries but these values reflect generation not only by hydropower but also by coal-fired, nuclear, and other means as well. The data given in Table 3 represent the production of electric power by power plants and combined heat and power plants minus the losses incurred through transmission, distribution, and transformation losses arising during operation of these plants (31). 426 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


Table 3. Electric Power Consumption for Selected Countries in 2011 Country

Electricity Consumption kWh/capita

Country

Electricity Consumption kWh/capita

Tanzania

92

Brazil

2438

Nigeria

149

Turkey

2709

Kenya

155

Argentina

2967

Senegal

187

China (w/o Hong Kong)

3298

Cameroon

256

Chile

3568

Ghana

344

Russia

6586

Pakistan

449

Israel

6926

Guatemala

539

Germany

7081

India

648

France

7292

Algeria

1091

United States

13,246

Egypt

1743

Sweden

14,030

Jordan

2289

Kuwait

16,122

Source: Adapted with courtesy of reference (31), World Bank, 2011.

As might be expected, electricity consumption worldwide varies widely, a reflection of the different geographies and corresponding economic development of each country. The World Health Organization (WHO) has estimated that consumption of 500 kWh/capita is necessary to maintain a reasonable quality of life that sustains economic viability. It is noteworthy that the sub-Sahara African countries listed in Table 3 do not meet this standard. African countries lag behind other regions in developing both their hydro-potential and water potential. About 600 million people in sub-Sahara Africa have no access to electricity. Africa’s major waterways- the Nile, Congo, Niger, Orange, and Senegal rivers- constitute a huge hydropower potential from a renewable energy source. Of these, only the Nile has been extensively harnessed to be a major source of electricity for the region it serves. Overall, hydropower contributed 22% to the energy demands of sub-Sahara Africa in 2012, although this figure varied considerably from region to region (32). The lack of adequate river regulation and the limited ability to constrain run-off variability negatively affect African economies. But Africa can bolster its energy imbalance and water supply for rural populations by developing its hydropower both at the local and regional levels. An example of a small scale project is the Sahanivotry Mini Hydro Power Plant which generates 15 MW of electricity. It is registered in Madagascar and supplies 10% of its electricity. Another example is the Buseruka Small Hydroelectric Power Project in Uganda which provides 9 MW of electricity and provides connections to the rural population (33). 427 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


The Songwe River Basin Development Plan is an example of a regional integration project intended to promote cooperation and governance of the transboundary water resources between Tanzania and Malawi. The project is geared to developing a 340 megawatt hydropower facility which will not only increase access to electricity for the 65 million people in the two countries but also provide energy for export and thus serve as an income generating mechanism. The project will also enhance freshwater storage supply, reduce the risks of overtopping flood plains and increase the total irrigated land area by 6000 hectares, thereby increasing crop yield (33). It seems evident that, in order to maintain water security, countries need to establish effective ways of storing freshwater. A reliable water storage capacity is a measure of a country’s ability to harness the multi-purpose activities essential for managing water: clean renewable energy for electricity generation, agricultural productivity, potable water supply, navigation, drought mitigation and flood risk management. Thus proper water management constitutes an indicator of economic prosperity. Figure 8 shows the reservoir storage capacity for selected countries.

Figure 8. Reservoir storage per capita 2003 (m3/cap). Source: Courtesy of David Grey and Claudia Sadoff from reference (34).

Water for Global Public Health How much water do people consume daily? The answer depends largely on where in the world people reside. Fresh water is distributed unevenly throughout our planet and accommodation to obtain a fair share of water available is the source of considerable conflict among nations sharing a common freshwater supply. For people residing in high-income countries with developed economies, water is used largely without regard to limitations. Thus in the US and Canada, for example, the average domestic and municipal consumption of water is about 570 liters per capita 428 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


per day. In European countries, where the culture encourages a lifestyle that is more water efficient, domestic and municipal use is considerably lower. In France for example, this water consumption is 280 liters per capita per day and in Germany it is 190 liters per capita per day. In low-income countries, where resources are seriously limited, daily consumption of freshwater is often below the basic level needed to ensure safe public health. In Ethiopia and Uganda, for example, the average domestic and municipal use of water in each country is about 15 liters per capita per day, a level too low to maintain good public health (35). This situation is similar to other countries in the developing world and has created conditions for consuming unsafe drinking water, which in turn, result in large scale infections, disease and morbidity. Diarrhea is a leading cause of waterborne diseases, 88% of which is attributed to unsafe drinking water. Each year 800,000 children under 5 die of diarrheal infection (36). Another disease that leads to chronic ill-health infection is schistosomiasis, which is acquired when people consume fresh water contaminated with larva of schistosomes, a parasite blood fluke. This disease affects more than 240 million people worldwide and occurs largely in endemic areas where infrastructure for clean water distribution is lacking. Widespread cholera is still observed in many countries. The use of untreated wastewater, excreta and grey water for agriculture poses additional serious health problems. In Bangladesh, arsenic contaminated water is a leading cause of cancer. Malaria and dengue fever are also diseases prevalent in marginalized communities. Remedies involving the simple household water treatment technology of boiling water can significantly reduce the incidence of water borne diseases but many affected communities lack the energy necessary to make this practice routine. Africans still rely on burning biomass as a source of energy, a practice that emits undesirable greenhouse gases. Another useful technology for water collection involving low capital investment is to harvest rainwater in large tanks that are filled via a large collecting funnel but recent drought, most acutely felt in poverty stricken areas, has led to insufficient input to accommodate large populations. Sanitation facilities that efficiently separate human excreta from human contact are obvious means to tackle the health problems arising within these societies but only 64% of the world population enjoys this technology. Health care wastes that consist of contaminated needles, blood, pharmaceuticals and medical devices risk infecting the workers and patients dependent on health care systems that are typically severely strained. WHO estimates that 4% of global disease burden could be alleviated by improving the available water supply (37).

Water Sector Management Strategies We have seen that allocating adequate water supplies in response to climate change, pollution, and growing populations worldwide are a clear necessity. To accomplish this mission, meticulous management of resources must be implemented at various levels, from data collection to supporting infrastructure to economic commitments. At the data level, monitoring water quality by measuring nutrient transport and pollutants in surface flows requires sustained input. In 429 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.


California, the state government has formed partnerships with several agencies to develop an integrated regional water management plan (38). Highly sophisticated data collection for monitoring groundwater is available from the pair of GRACE satellites orbiting the Earth that were launched by NASA in 2002 to detect slight variations in the gravity field due to moving water. The data recorded can serve as guides to avoid overexploitation of aquifers (39). As for infrastructure, the upgrading and maintaining of aging and existing water distribution pipelines and storage are of paramount importance. At the present time, Israel’s agricultural sensors and data imagery collection are the most sophisticated in the world and the high yield in productivity is testimony to their efficacy. More broadly, financing and maintaining water systems in the developing world are projects in dire need. While specific interventions necessarily reflect regional needs, some applications such as drip irrigation and tapping rivers for electricity in Africa rely mainly on low capital investments. For the high capital investments typical of developed countries, appropriate oversight should be adopted to prevent pollution of freshwater by industrial contaminants or fertilizer run-off from farmlands, with financial penalties imposed for failure of compliance. Attracting private sector financing can be achieved if goals for successful implementation are clearly defined and implemented. Innovative incentives, such as tax breaks, should be offered to the private sector to encourage investment. Economic benefits can be attained by promoting partnerships among nations to share water supplies and costs, a feature that furthers cooperation rather than collision. Overall, developing effective institutional infrastructure and sufficient specialized human capabilities for managing water, adopting legal instruments governing water at regional, national, and international levels are sound policy.

Conclusions Competing forces of demands from an expanding world population and alterations in the water cycle due to climate change are severely straining the world’s fresh water supply. Applications of innovative technologies, such as those described in this paper, have proven effective in adapting and mitigating potential crises. Further advances in these technologies are still needed to improve their efficacy and reduce the ramifications that negatively impact ecosystems. As demands for water intensify, regional integration will provide benefits of enhanced security of supply, improved public health, more reliable food supply, and better economic efficiency. Protecting water security both for availability and safety must become a priority to avert global suffering. Managing water demand is an important strategy: rationing where it is scarce, high pricing where it is plentiful, but above all, enforcing appropriate conservation measures everywhere. Overall, commitments of countries in all regions to monitor water use and related infrastructure will be imperative to sustain water resources at a level that provides reasonable quality of life and ensures economic viability for all populations.

430 In Water Challenges and Solutions on a Global Scale; Loganathan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.

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