Virtual water : Also called embedded water, is water that has been used in the production of food etc. Includes resources also for irrigation, processing and packaging of produce.
Green water: Water that comes directly from rainfall or the soil. Generally replenished, but climate change will alter patterns of rainfalland there could be a decline in many parts of the world. Blue water: Withdrawn fromground-water or surface reserves. Inmany areas blue water is being used faster than nature replenishes it.
Infrastructure is the key to avoiding water scarcity. It needs to guarantee safe, fair and regular access to water. Poverty is the biggest barrier to water security. Scarcity often has its roots in water shortage, and it is in the arid and semiarid regions affected by droughts and wide climate variability, combined with population growth and economic development, that the problems of water scarcity are most acute.
MDG 1: Access to water for domestic and productive uses (agriculture, industry, and other economic activities) has a direct impact on poverty and food security. MDG 2: Incidence of catastrophic but often recurrent events, such as droughts, interrupts educational attainment.MDG 3: Access to water, in particular in conditions of scarce resources, has important gender related implications, which affects the social and economic capital of women in terms of leadership, earnings and networking opportunities. MDGs 4 and 5: Equitable, reliable water resources management programmes reduce poorpeoples vulnerability to shocks, which in turn gives them more secure and fruitful livelihoods to draw upon in caring for their children. MDG 6: Access to water, and improved water and wastewater management in human settlements, reduce transmission risks of mosquito-borne illnesses, such as malaria and dengue fever. MDG 7: Adequate treatment of wastewater contributes to less pressure on freshwater resources, helping to protect human and environmental health. MDG 8: Water scarcity increasingly calls for strengthened international cooperation in the fields of technologies for enhanced water productivity, financing opportunities, and an improved environment to share the benefits of scarce water management.
Around 700 million people in 43 countries suffer today from water scarcity. By 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity, and two-thirds of the worlds population could be living under water stressed conditions. With the existing climate change scenario, almost half the worlds population will be living in areas of high water stress by 2030, including between 75 million and 250 million people in Africa. In addition, water scarcity in some arid and semi-arid places will displace between 24 million and 700 million people.Sub-Saharan Africa has the largest number of water- stressed countries of any region.
Water use has been growing far faster than the number of people.During the 20th century the world population increased fourfold, but the amount of freshwater that it used increased nine times over. Already 2.8 billion people live in areas of high water stress, the report calculates, and this will rise to 3.9 billion – more than half the expected population of the world – by 2030. By that time, water scarcity could cut world harvests by 30 per cent – equivalent to all the grain grown in the US and India – even as human numbers and appetites increase. Some 60 per cent of Chinas 669 cities are already short of water. The huge Yellow River is now left with only 10 per cent of its natural flow, sometimes failing to reach the sea altogether. And the glaciers of the Himalayas, which act as gigantic water banks supplying two billion people in Asia, are melting ever faster as global warming accelerates. Meanwhile devastating droughts are crippling Australia and Texas. ‘The Independent’ Newspaper
Developing countries should invest in water management strategies that combine infrastructure with "natural" options such as safeguarding watersheds, wetlands and floodplains. Japan and Cambodia experience about the same average rainfall - about 160cm per year. While the average Japanese person can use nearly 400 litres per day, the average Cambodian must make do with about one-tenth of that.
The principal cause of increasing waterstress is growing water withdrawals, and themost important factor for this increase is thegrowth of domestic water use stimulated byincome growth. Streams that are important for small communities in Tanzania may godry for half the year, largely because people are taking more and more water for irrigating crops.
Singapores NEWater is produce from waste water supplies. NEWater is supplied to industries for process use as well as commercial and institutional complexes for air-con coolingpurposes. This frees up potable water for domestic use. Because the area lacks enough watersheds and rivers to draw water for domestic use, it imports water (as much as 40% of its supplies) and has invested significant amounts of land to create watercatchments. NEWater contributes to the domestic potable water supply. To make potable water out of what goes down the drain and toilet, Singapores recycling plants use a three-step purification process: micro-filtration, reverse osmosis, and ultraviolet treatment. The end product meets drinking water standards set by the World Health Organisation
Economic water scarcity occurs when water is available but inaccessible because of a lack of investment in water provision or poor management and regulation of water resources. Much of the water scarcity of sub-Saharan Africa falls into this category. Signs of scarcity are plentiful. Several major rivers,including the Indus, Rio Grande, Colorado, Murray-Darling, and Yellow, no longer reach the sea year-round as agrowing share of their waters are claimed for various uses. Worldwatch Institute
Water tables are falling as groundwater is over-pumped in South Asia, northern China, the Middle East, North Africa, and the southwestern United States, often propping up food production unsustainably. The World Bank estimates thatsome 15% of India’s food, for example, is producedusing water from nonrenewable aquifers. Another sign of scarcity is that desalination, a limited and expensive water supply solution, is on the rise. Worldwatch Institute
Worldwide dam construction has reduced from 1951-77 (360/year) to 1992 (170/year) About 40% of worlds population live in river basins whose watersheds are shared by more than two countries – power of upstream nations • Syria / Jordan / Israel have conflicts over the Jordan River • Egypt / Sudan / Ethiopia have conflicts over the Nile River• Iraq / Syria / Turkey have conflicts over the Tigris-Euphrates Rivers • Bangladesh / India have conflicts over the Ganges River
“Water is only a renewable resource if we respect the ecological processes that maintain and give stability to the water cycle” The right to use water comes with responsibilities to preserve and protectwater must be considered to be more than just a “resource” – it is the basis of life
The water required for a meat-eating diet is twice asmuch needed for a 2,000-litre-a-day vegetarian diet. When 50% of food is wasted after it leaves farmers fields, it leads to an equivalent water waste of 50% because wasted food is also wasted water.Each of us can make a difference if we first consider the water implications of our lifestyles and the "water footprint" we are leaving behind.
Farmers are adopting more precise irrigation practices, such as drip and sprinkle irrigation. For example, many farmers in Nepal and India now regularly use low-cost drip irrigation to grow vegetables. In sub-Saharan Africa, just a little water - combined with improved crop varieties,fertiliser and soil management - can go a long way. Farmers can double the yield per hectare they currently harvest,and double the amount of food produced per unit of water.Over the last two decades in Asia, sales of pumps that allowfarmers to more reliably and precisely apply water to their crops, have risen dramatically. Rice farmers are now also saving water by a practice known as "wet and dry" irrigation, rather than following the traditional practice of keeping rice fields constantly flooded.