This chapter is from the book
This chapter is from the book
This chapter is from the book
Some Water Facts
As we all go about our daily lives, we need water for drinking, cooking, washing ourselves and our clothes, removing our wastes, watering parks and gardens, and cleaning our houses, cars, and so on. To those of us living in "western" countries, water is available at the turn of a tap and at a cost, at least until recently, so negligible that we give it little thought. When we add up these uses, most of us manage on approximately 100–550 liters (26–145 U.S. gallons) per day depending on our climate and degree of profligacy (see Figure 1.1). However, billions of people worldwide still do not have access to safe drinking water and sanitation facilities. In June 2009,2 three people were murdered following a fight over who should have first access to an illegal water connection in Bhopal, India. In other parts of the world, people often have to collect water from a standpipe in the street or even walk several kilometers to nearby rivers, lakes, or wells. In such cases, their survival is often based on usages of less than 50 liters (13 gallons) per day.
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Figure 1.1 Per capita daily water usage
Source: UNDP, Human Development Report 2006 (http://hdr.undp.org/en/media/HDR06-complete.pdf) and www.data360.org
This book predominantly focuses on water use in agriculture. As a consequence some of the volumes involved become mind-boggling. Table 1.1 sets out commonly used metric and approximate comparisons with U.S. imperial units used for water measurement. The somewhat archaic acre-foot U.S. unit represents the amount of water that has to be applied to flood an acre to a depth of one foot. To put things in perspective, an Olympic size swimming pool of 50 x 25 x 2 meters (184 x 64 x 6' 7" feet) contains about 2.5 ML (660,000 gallons). Lake Mead in the Western United States impounds a maximum volume of 35.2 km3 (28,500,000 acre-feet). Throughout the book, while we try to keep numbers to a minimum, we quote the original unit of measurement first and then put its metric or imperial equivalent in parentheses.
Table 1.1. Conversion of Metric to U.S. Imperial Measurements of Water
|
Metric |
US Imperial |
|
|
Gallons |
Acre-feet |
|
|
1 Kiloliter (KL) = 1000 liters |
264 |
0.00081 |
|
1 Megaliter (ML) = 1,000 KL or 1,000,000 liters |
264,000 |
0.81 |
|
1 Gigaliter (GL) = 1000 ML |
264,000,000 |
810 |
|
1 cubic meter (1m3) = 1000 liters |
264 |
0.00081 |
|
1 km3 = 109 m3 = 1012 liters or 1000 GL |
264,000,000,000 |
810,000 |
|
Source: UNDP-Human Development Report, 2006 |
||
In 2002, many countries committed themselves to the UN's Millennium Development Goals that included ambitious targets of halving by 2015 the number of people without access to safe drinking water and sanitation. While the drinking water target may be met, there is increasing concern that the sanitation target won't be met. The sheer task of meeting these targets is, furthermore, putting national government, donors, and aid agencies under considerable financial and other pressures, although the actual demand on water resources for drinking water is not particularly large. However, dealing with sewage, as more and more people get connected to sanitation systems in the world's growing cities, is going to be one of the world's greatest challenges in the forthcoming decades, particularly from the water quality, health, and environmental viewpoints. Many rivers in developing countries are now, in terms of pollution and poor water quality, similar to the putrid streams seen in cities like London in the nineteenth century.
In many ways, the goal that everybody should have access to safe drinking water and sanitation facilities has masked the fact that the real future demand on the world's freshwater resources will come from the use of water in agriculture for both food and fiber production (see Figure 1.2). Data from many countries with a significant agricultural base demonstrate that upwards of 70% of total water use goes to agriculture. This applies to developed areas such as California and Australia, just as much as to developing countries. When we examine the data for agricultural water use, drinking and sanitation water uses pale into insignificance. For example, a metric ton of rice requires up to 998,570,358 gallons (3780 ML) of water for its growth. A kilo or about 2 pounds of grain-fed beef requires about 2460 gallons (10,000 liters or 10,000 ML per ton). On average, every calorie consumed in our food requires a liter of water for its production, and this does not count water used by the food processing industries. Furthermore, "western" diets rich in animal products as compared with simpler (and healthier!) predominantly vegetable- and cereal-based diets require even greater volumes of water per calorie produced.
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Figure 1.2 Agriculture is the largest water user often via irrigation. For example, irrigation has for centuries been the mainstay of Sri Lanka's agricultural economy. It is based on the construction of large reservoirs (tanks) which capture and store wet season rainfall.
Photo: Colin Chartres
Consequently, each person on the planet, if consuming a diet of 2500 calories per day, accounts for at least 660 gallons (2500 liters) of water requirement. Multiplied by 365 days per year this totals 241,056 gallons (912,500 liters, or nearly a megaliter). When we look at global population growth, which has climbed steeply in the last 50 years and is predicted to climb from about 6.7 billion in 2008 to about 9 billion in 2050 (see Figure 1.3), the future water requirement just to feed so many people, based on current levels of agricultural productivity, is approximately 3360 cubic miles (14,000 km3).3 The predicted extra 2 billion mouths equate to developing another 600–1440 cubic miles (2500–6000 km3) of water resources. This equals at least another 25–50 enormous dams of the capacity (approximately 110 km3) of the High Aswan Dam on the River Nile in Egypt. Herein lies the catch. These vast amounts of water are not available or at least not available in the areas where we need them to produce food.
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Figure 1.3 Global population trends
Source: Trends in population, developed and developing countries, 1750-2050 (estimates and projections). 2009. Hugo Ahlenius, Nordpil, UNEP/GRID-Arendal Maps and Graphics Library. Retrieved 07:19, April 22, 2010 from http://maps.grida.no/go/graphic/trends-inpopulation-developed-and-developing-countries-1750-2050-estimates-and-projections.
Politically, one of the most pressing questions for many countries over the next 50 years will be whether they will be food-secure in the face of potential recurring world food crises. During the 2008 food crisis, although global food stocks reached worrying lows, there was still enough food available to feed everyone. The key problems were those of demand, driving prices above the reach of the poor and food stocks being geographically in the wrong place. Logically, for most countries, food security can be achieved by a combination of domestic production and imports, but as was observed in the 2008 food crisis, logic often flies out the window in the face of adversity. Some food exporting countries adopted policies that were clearly driven by fear and stopped exports. Other countries froze grain prices, which was detrimental to poor farmers, encouraged black marketeering, and did little to aid the urban poor. So some critical needs for many countries are policy settings that encourage domestic production via increasing productivity, recognizing the benefits of importing "virtual water" via trade in food, and enabling poor farmers to benefit from rising prices so that they in turn can invest in more productive systems. Irrespective of individual countries' different policy responses to food crises, it seems inevitable that increasing pressures for food security will play a big role in determining water policy and management responses.
Much of the world is already water-scarce. The availability of water and access to water will be major issues for economic development and for the livelihoods of the poor, given that they often suffer most when resources are scarce. Water scarcity can be described as being physical or economic in nature (see Figure 1.4).
Physical water scarcity results from the allocation of virtually all available water supplies, leaving nothing for additional use or for the future or for the environment.
Water scarcity has become a reality for many regions. Much of south and west Asia, China, the Middle East, Northern and Southern Africa, Southern Australia, and the Southwestern United States are in this category. Physical water scarcity will put increasing pressure on water planners and managers to develop ways to better manage their existing water resources, to increase the productivity of water, and to develop "new" sources of water, that is, "reuse" of wastewater. Many countries have already seen water users turn to groundwater often not cognizant of the high degree of connectivity between groundwater and surface water.
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Figure 1.4 Global water scarcity in 2000
Source: Comprehensive Assessment of Water Management in Agriculture
There are, however, many areas in the developing world, in particular in sub-Saharan Africa and parts of Southeast Asia, where there are still available water resources, but development and use of these resources has been constrained by lack of capital investment or appropriate institutions to support the use of that capital. The resulting "economic" water scarcity has major ramifications for the poor and economic development in general, and its solution has the potential to bring global benefits and reduce stresses on other water-scarce areas. The issue of insufficient infrastructure development also relates to limited investment in wastewater treatment facilities and the consequent widespread pollution of clean surface water bodies. Whether in areas of physical or economic water scarcity, a critical factor for the future will be the impact of climate change and ongoing and potentially increasing climatic variability on the availability and use of water resources be it for drinking water, hydropower, or irrigation. The impact of climate change will vary depending on geography and scale. In some areas, total rainfall and intensity will increase, causing flooding, crop damage, and erosion. In other areas, total rainfall may decrease, wet seasons become shorter, and variability more extreme with greater frequency of droughts. Learning how to store water better and providing supplementary irrigation to make up for erratic rainfall supplies will be the key to overcoming these challenges. Climate change and potential adaptation are discussed in more detail in later chapters.
So, the preliminary facts and figures presented here demonstrate very considerable cause for concern as to where we are going to get the water that will be needed to sustain us in the future. It is not appropriate to brush off this concern by saying that I live in a country well-endowed with water resources, and this is therefore not my problem. Local and regional problems these days tend to escalate politically and physically across the globe. Water scarcity and food scarcity in one place, just like political oppression, manifest themselves in the form of political and social unrest and illegal migration, which can become of major concern to neighboring and receiving countries, respectively. The following chapters explain in more detail the nature and dimensions of water availability and use at the global level and look at their severity and likely future impact both regionally and internationally. From our perspective, although we believe that a water crisis is imminent, we do not believe that panic and kneejerk solutions are the way forward. The book is written around the key concept of using scientific and socio-economic evidence as the basis for reform and management action in the water sector. It also focuses on the need to look at water issues in an integrated fashion as opposed to dealing with water supply, sanitation, agricultural, and environmental water separately. What is for sure is that given the pressures facing water supply and demand and their management, we can't continue using practices developed, in some cases, over 150 years ago. We have to change the way we do "business" in the water sector once and for all. As well as looking at the problems, we explore the right and wrong ways that they can be tackled and put considerable focus on mixtures of low tech, high tech, socio-economic and governance solutions to the world's water problems.