In recent years, a number of estimates have predicted a global water crisis that will affect the capacity of both potable and agricultural water supply to meet the basic needs of humanity. By the year 2050, global grain production will have to be doubled in order to meet the demand of a growing global population with changing consumption patterns to more protein-based diets at a time of climatic changes. There are large variations in the estimates to what extent water scarcity will impact human and economic development, but the projected rise in the number of people living in water-scarce regions ranges 1-2.5 to 3-9 billion over the next century. There is no single definition of the global water crisis: in general, however, a crisis is defined to be 1) a major threat to system survival with 2) little time to respond 3) involving an ill-structured situation, and 4) where resources are inadequate to cope with the situation.
In a growing number of media reports and scientific and development publications, the coming water crisis as a result of water scarcity is increasingly being recognized as a growing concern for many countries around the globe. For instance, the World Economic Forum warns that “Water security (whether it be the challenge of too little water over long periods of time, or too much water all at once) is one of the most tangible and fastest-growing social, political and economic challenges faced today. It is also a fast-unfolding environmental crisis. In every sector, the demand for water is expected to increase and analysis suggests that the world will face a 40% global shortfall between forecast demand and available supply by 2030”.
The United Nations Environmental Programme’s Green Economy chapter on water further highlights that “continuing current practices will lead to a massive and unsustainable gap between global supply and demand for water withdrawal. This is exacerbated by failure to collect and treat used water to enable subsequent uses. With no improvement in the efficiency of water use, water demand is projected to overshoot supply by 40 per cent in 20 years’ time. Historical levels of improvement in water productivity, as well as increases in supply (such as through the construction of dams and desalination plants as well as increased recycling) are expected to address 40 per cent of this gap, but the remaining 60 per cent needs to come from investment in infrastructure, water-policy reform and in the development of new technology. The failure of such investment or policy reform to materialize will lead to the deepening of water crises”.
Since 90% of global water resources are used for food production, the water crisis will particularly affect agricultural water use and thus food security. The main challenge will therefore be the improved efficiency of agricultural water management in order to produce 50% more food by 2050 to meet global demand. The International Water Management (IWMI) therefore summarized the challenges as “it is possible to produce the food—but it is probable that today’s food production and environmental trends, if continued, will lead to crises in many parts of the world. Only if we act to improve water use in agriculture will we meet the acute freshwater challenges facing humankind over the coming 50 years”.
Water stress indicators
Since water is a temporal-scalar resource, the watershed is the priority realm that needs to be analysed. In order to map the water crisis, so-called “water stress indicators” have been developed to illustrate the vulnerability of certain regions and watersheds, as well as to ascertain“how much water is necessary to meet human demands, then the water that is available to each person can serve as a measure of scarcity”.
The most widely cited water stress indicator is the Falkemark Indicator which is defined “as the fraction of the total annual runoff available for human use. Multiple countries were surveyed and the water usage per person in each economy was calculated. Based on the per capita usage, the water conditions in an area can be categorized as: no stress, stress, scarcity, and absolute scarcity. The index thresholds 1,700m3 and 1000m3 per capita per year are used as the thresholds between water stressed and scarce areas, respectively”.
Water stress index
The water stress index method is commonly used because it is easy to use and the data needed is readily available. However, it has been criticized as being too simplistic because
1. it ignores important regional differences in water availability, only measuring water scarcity at country level;
2. it fails to account for whether or not those water resources are accessible. For example, some of the freshwater resources of a country may be stored deep underground or may be heavily polluted;
3. it does not include man-made sources of freshwater such as desalination plants which increase water availability beyond what is naturally available; and
4. it does not account for the fact that different countries, and regions within countries, use different amounts of water. In Australia for example, most of the demand for water is focused around the major urban and agricultural centres in the Murray-Darling Basin, with much less demand in the sparsely populated centres.
An alternative way of defining and measuring water scarcity is to use a criticality ratio. This approach counters the assumption that all countries use the same amount of water. Instead, the criticality ration defines water scarcity in terms of each country’s water demand compared to the amount of water available and measures scarcity as the proportion of total annual water withdrawals relative to total available water resources. Using this approach, a country is said to be water scarce if annual withdrawals are between 20-40% of annual supply, and severely water scarce if they exceed 40%.
While the criticality ration approach avoids the overly simplistic assumption that all countries have the same demand for water, it also has its limitations:
1. it does not consider man-made increases in water supply (such as desalination);
2. it ignores water withdrawals that are recycled and reused; and
3. it does not consider the capacity of countries to adapt to lower water availability through changing behavior or new technology.
A third measure of water scarcity was developed by the International Water Management Institute (IWMI). This approach attempts to counter the problems listed above by 1) including each country’s water infrastructure, such as water in desalination plants, into the measure of water availability; 2) including recycled water by limiting measurements of water demand to consumptive use rather than total withdrawals; and 3) measuring the adaptive capacity of a country by assessing its potential for infrastructure development and efficiency improvements. IWMI classifies countries that are predicted to be unable to meet their future water demand without investment in water infrastructure and efficiency as economically water scarce. Countries predicted to be unable to meet their future demand, even with such investment, are termed physically water scarce. While the IWMI measure of water scarcity is more sophisticated, its complexity means that it requires significant amounts of time and resources to estimate. This approach also fails to consider the ability of people within countries to adapt to reduced water availability by importing food grown in other countries, or by using water saving devices. The ability to adapt also depends on the economic resources available in countries as a whole, as well as to individuals within a country. For instance, wealthy residents in rich countries are more likely to be able to adapt to reduced water availability than poor people in developing countries.
Water poverty index
A fourth approach to measuring water scarcity is the water poverty index. This approach attempts to take into account the role of income and wealth in determining water scarcity by measuring 1) the level of access to water; 2) water quantity, quality, and variability; 3) water used for domestic, food, and productive purposes; 4) capacity for water management; and 5) environmental aspects. The complexity of this approach, however, means that it is more suited for analysis at a local scale, where data is more readily available, than on a national level.
The US scientist Peter Gleick developed a different approach to communicate the looming water crisis to the public, which he called “peak water” in an allusion to the peak oil theory. By using the so-called “Hubbert Curve”, he suggests that the over-use and over-allocation of what he terms 1) non-renewable water, 2) renewable water, and 3) ecological water may have already surpassed peak limits. This does not mean the world will run out of water due to the hydrological cycle but that humanity uses more water than the ecosystems can sustain at high costs to environmental degradation. Gleick’s concept highlights the need to find alternative ways to manage global water resources in order to address the looming water crisis.
- ↑ R. Taylor. (2010). Rethinking water scarcity: the role of storage. Available online: http://www.odi.org.uk/sites/odi.org.uk/files/odi-assets/events-presentations/687.pdf (accessed 29.12.2012).
- ↑ A. Mishra. (1996). Organisational Responses to crisis: the centrality of trust. Available online: http://18.104.22.168:8080/dspace/bitstream/123456789/105/1/Organizational%20responses%20to%20crisis%20Mishra.pdf (accessed: 29.12.2012).
- ↑ World Economic Forum. (2012). Water. Available online: http://www.weforum.org/issues/water/index.html (accessed 29.12.2012).
- ↑ United Nations Environmental Programme. (2011). Green Economy Report. Available online: http://www.unep.org/greeneconomy/greeneconomyreport/tabid/29846/default.aspx (accessed 29.12.2012).
- ↑ Comprehensive Assessment of Water Management in Agriculture. (2007). Water for Food, Water for Life: A Comprehensive Assessment of Water Management in Agriculture. London: Earthscan, and Colombo: International Water Management Institute.
- ↑ F. Rijsberman. (2006). Water scarcity: Fact or Fiction? In Agricultural Water Management 80 (2006): 5-22.
- ↑ M. Falkenmark. (1990). Rapid Population Growth and Water Scarcity: The Predicament of Tomorrow's Africa. In Population and Development Review (Population Council) 16 (1990): 81-94.
- ↑ 8.0 8.1 8.2 8.3 Global Water Forum. (2012). Understanding Water Scarcity. Available online: http://www.iwmi.cgiar.org/news_room/pdf/Understanding_water_scarcity.pdf accessed 29.12.2012.
- ↑ C. Sullivan. (2002). Calculating a Water Poverty Index. World Development (Elsevier Science Ltd) 30, no. 7 (2002): 1195-1210.
- ↑ P.H. Gleick and M. Palanappian. (2010). Peak water limits to freshwater withdrawal and use. Available online: http://www.pacinst.org/press_center/press_releases/peak_water_pnas.pdf (accessed: 29.12.2012).