that had previously been straightened and have become rather dull and monotonous, with low ecological and geomorphological diversity, are now being rehabilitated through the installation of meander bends, removal of concrete bank linings and addition of woody debris (Palmer and Bernhardt, 2006). The EU Water Framework Directive requires that water bodies must be in good ecological status and efforts must be under - taken by all EU member states to improve the status of water bodies. In other words, legisla- tion is in place to protect water bodies for their own sake as well as for the sake of society, which enjoys and relies on water bodies for the wider benefits it receives from them. Further informa- tion about the EU Water Framework Directive is provided in Chapters 4, 6 and 10. However, there is still a tension between rehabilitating rivers or having ‘natural-looking’ water landscapes and societal expectations around issues such as flood management, where flood defences are still expected to be in place (see Chapter 3).
E Global water resources
1 The amount of water available
The Earth’s hydrosphere contains a huge amount of water – about 1388 million cubic kilometres (see also Chapter 2). However, approximately 97% of this amount is saline water and only 3% is freshwater (Figure 1.6), although as Chapter 2
notes there are large uncertainties as to the exact values of the stores. The greater portion of this freshwater (between 48 and 69%) is in the form of ice and permanent snow cover in the Ant- arctic, Greenland, other parts of the Arctic and the moun tainous regions. While 30% of fresh- water exists as groundwater, <1% of the total amount of freshwater on the Earth is concen- trated in lakes, reservoirs and river systems. Hence <1% of the total available water is most easily accessible for our economic needs, and at the same time it is vital for land-based aquatic ecosystems. Water is the most widely distributed substance on our planet. Although it is available everywhere its availability varies across the world. The mean value of the renewable global water resource is estimated at 42,700 km3per year, and this is ex -
tremely variable in space and time (Shiklomanov, 1998). At the continental level, the Americas have the largest share of the world’s total freshwater resources with 45%, followed by Asia with 28%,
The world’s water
Freshwater Salt-water Groundwater Ground ice and permafrost Other Glaciers and permanent snow
Freshwater distribution Freshwater distribution in other categories Lakes Soil Atmosphere Wetlands Rivers Other
Figure 1.6 Categories of world water resources. REFLECTIVE
QUESTION
How did control of water resources enable civilisations to develop?
Europe with 16% and Africa with 9%. A country- level analysis shows that nine countries are world giants in terms of internal water resources (total surface and groundwater, not accounting for transboundary waters or border rivers), account - ing for 60% of the world’s natural freshwater (Table 1.2). As shown in Table 1.2, twelve coun - tries are water-poor countries and they are mostly small (notably islands) or arid ones. However, the values shown in Table 1.2 do not entirely reflect the amount of water available for each person, as countries differ so much in area and in population.
Look at Figure 7.4in Chapter 7, which maps the amount of freshwater available per person per year in different parts of the world. Falken- mark (1986) proposed a threshold of 1000 and 500 m3of freshwater per inhabitant to correspond
respec tively to the water stress and water scarcity levels. Note that in Figure 7.4 the OECD has used less severe thresholds to define scarcity (<1000 m3) and stress (<1700 m3) although it
does define severe water scarcityas freshwater <500 m3per person per year (see section D in
Chapter 7). Therefore you need to be aware of different definitions for these terms. Falken-
mark (1986) felt that in an average year, 1000 m3
of water per inhabitant can be considered as a minimum to sustain life and ensure agricultural production in countries with climates that require irrigation for agriculture. There are currently 28 countries which have less than 500 m3 of
water internally available to them per person per year and 45 countries with less than 1000 m3
per person per year. Among these countries are Egypt (22), Saudi Arabia (85), Singapore (115), Niger (218), Pakistan (311), Hungary (602), the Netherlands (660) and South Africa (887) (values in brackets are m3per person per year). Some
countries are undergoing very rapid industrial - isation and popu lation growth, which puts their water resources under stress even if the total water resources avail able within the country are large. India, for example, currently has around 1165 m3
per person per year of internally available renew - able freshwater (compare this to 9000 for the USA or 70,000 for New Zealand), but this has decreased from 3100 in the early 1960s and 2000 in the early 1980s (Box 1.1). See also Figure 2.15in Chapter 2, which provides a map showing the number of people across the world estimated to be subject to severe water scarcity.
Table 1.2 Water-rich and poor countries of the world
Water-rich countries Total resources Water-poor countries Total resources
(km3yr–1) (km3yr–1)
Brazil 8233 Israel 1.67
Russia 4507 Jordan 0.88
Canada 2902 Libyan Arab Jamahiriya 0.60
Indonesia 2838 Mauritania 11.40
China (mainland) 2076–2830 Cape Verde 0.30
Columbia 2132 Djibouti 0.30
USA 2071 United Arab Emirates 0.15
Peru 1913 Qatar 0.05
India 1897 Malta 0.05
Gaza Strip 0.06
Bahrain 0.12
Kuwait 0.02
Source: Data from FAO (2003).
There are 44 countries in the world which depend on other countries for over 50% of their renewable water resources. These countries are: Argentina, Azerbaijan, Bahrain, Bangla- desh, Benin, Bolivia, Botswana, Cambodia, Chad, Congo, Djibouti, Egypt, Eritrea, Gambia, Iraq, Israel, Kuwait, Latvia, Mauritania, Mozambique, Namibia, Netherlands, Niger, Pakistan, Paraguay, Portugal, Republic of Moldova, Romania, Senegal, Somalia, Sudan, Syrian Arab Republic, Turkmen - istan, Ukraine, Uruguay, Uzbekistan, Vietnam and the seven independent countries that made up the former country of Yugoslavia.
2 Increasing demand for water use and consumption
Water can be used both in-stream and off-stream. In-stream water use refers to direct use of water in rivers or lakes where there is no withdrawal of the water. For example, the uses of water for navigation, hydropower, tourism and fisheries are all in-stream water uses. Off-stream water use involves withdrawal of the water from the source. Where water is withdrawn and then not returned to the resource that provided it, this is known as
consumptive water use. Examples might include manufacturing, where water is abstracted for cooling, which results in evaporation of the water, or water used in food preparation, where the water is not returned to the stream. Agricultural con - sumptive water use includes the water transpired by plants plus losses from evaporation from the soil surface and leaves in the crop area. Good farming practice attempts to reduce crop water consumption to its most efficient minimum.
The world’s population is growing by about 80 million people a year, implying increased freshwater demand of about 64 billion cubic metres a year (UNESCO, 2009). An estimated 90% of the 2.5 billion people who are expected to be added to the population by 2050 will be in developing countries, many in regions where the current population does not have sustainable
access to safe drinking water and adequate sanitation. Good sanitation is important for health (see Chapter 8), yet 2.5 billion people have to use hygienically unsafe toilets or have to defecate on open land. Poor sanitation causes a myriad of water-borne diseases, including severe diarrhoea which kills around 1.5 million children each year. As populations grow, demand for water increases, due to escalating demand from dom estic, agri - cultural and industrial sectors. While the world - wide demand for water is increasing every year, water supply cannot remotely keep pace with the demand.
By 2025, 52 countries containing two-thirds of the global population are expected to be short of water. To many, this is seen as a water crisis. According the Asian Development Bank, China and India (Box 1.2) alone are forecast to have a combined supply shortfall of one trillion cubic metres in 2030. Within Asia, other countries at or near water stress conditions are Bangladesh, Cambodia, Nepal, Pakistan, the Philippines and Vietnam (Richardson, 2010). With the addition of another 1.5 billion people to feed in Asia by 2050 there will be unprecedented stress on water supply in the region.
In developing countries, industry is an essential engine of economic growth, and the industrial demand for water is likely to increase. Global annual water use by industry is expected to rise from an estimated 725 km3in 1995 to about 1170
km3 by 2025, by which time industrial water
usage will represent 24% of all water abstractions. See also Figure 7.2in Chapter 7 for a 2030 predic - tion from major industrial organisations. Much of the increase will be in developing countries now experiencing rapid industrial development (UNESCO, 2003). This will further intensify com - petition between the domestic, industrial and agricultural sectors for water, leading to sectoral water conflicts (see Chapter 11). Figure 1.8shows industrial water use per region, compared with other main uses determined by UNESCO (2003). Clearly, such figures depend on exactly how you
carve up the sectors and, as shown in Chapter 12, there are other ways of accounting global water use. Hoekstra and Chapagain (2008), for example, estimated that 86% of global water use is for agri - culture and processing of agricultural products, 10% is for industry and the rest is for domestic consumption.
Agriculture is the largest consumer of water for human use. Most water for agriculture comes from rainfall stored in the soil profile and only 15% is provided through irrigation. However, of the 3800 km3water abstracted from rivers and
groundwater, 70% is used for agricultural irri - gation (Molden et al., 2007). Additional water required for agriculture under forecasted popula - tion growth will strain ecosystems and increase
competition for water resources. While efforts to reduce water consumption in Europe and North America for industry and domestic use are sensible, for the rest of the world the focus needs to be on using water more efficiently in agri - cultural processes.
There appear to be five key ways of increasing water efficiency for global agriculture:
• focus efforts in areas with currently low agricultural yields
• improve soil fertility in arid and semi-arid areas
• use trade to manage water efficiency • reduce evaporation
• use biotechnology.
India’s looming water crisis
India’s demand for water is growing at an alarming rate. India currently has the world’s second largest population, which is expected to reach a staggering 1.6 billion by 2050, put - ting enormous strain on water resources. The burgeoning population, un planned urban isation, and growing sectoral demands put tremendous pressure on fresh water resources. Estimates of total usable water resources range from 668 billion cubic metres to 1086 billion cubic metres (NCIWRD, 1999; Narasim han, 2008; Garg and Hassan, 2007). Which ever estim ate one accepts, there is no escaping the fact that water availability in India is inexorably approaching the scarcity benchmark of 1000 cubic metres per capita (Figure 1.7). With unabated growth in irriga - tion and even more rapid growth in industrial and dom estic water demand, water shortages seem inevitable.