Environment Counts | National Water Footprints
Author: Rick Higgins – Published At: 2011-07-20 22:02 – (1162 Reads)
A conceptual breakthrough that enabled an integrated land-water approach came at a UN Food and Agriculture Organization seminar in January 1993 when the concept of green water was proposed for soil moisture.
Incorporating the concept of green water into the bigger picture made it possible to understand not only the water implications of land cover change, but also the water scarcity problems of rainfed agriculture in the semiarid regions of sub-Saharan Africa and South Asia.
These problems had earlier tended to hide behind concepts like the â€œhunger gapâ€ and â€œdroughts and desertification.â€ Since many of the problems in the semiarid tropics in sub-Saharan Africa are linked to the water in the soil, this conceptualization resulted in renewed efforts to come to grips with the food production challenges and drought problems in that zone. It opened the possibility to address the â€œdrought and desertificationâ€ problem from the perspective of the waterâ€™s presence rather its absence.
Rising Demands on an Overappropriated Resource
Warnings regarding the foreseeable increase in water requirements to feed a growing world population had been brought up already by the Swedish Delegation at the UN Conference on Population 1974 and were highlighted again at the UN Water Conference in Mar del Plata and in publications such as the book Water for a Starving World.
This type of analysis continued in a study of the foreseeable difficulties of African countries to be food self-sufficient. The blue water perspective of global food production was further discussed at a 1996 meeting, â€œLand Resources: On the Edge of the Malthusian Precipice?â€ held by the Royal Society in London, where interregional blue water differences were distinguished. In demand-driven water scarcity, there is a high usage compared to the availability of water, whereas in population-driven water scarcity (also known as water crowding), many people are dependent on finite water supplies.
During the 1990s, an additional difficulty emerged in terms of the consequence in the semiarid regions of the irrigation-based â€œGreen Revolutionâ€ that made countries like India become self-sufficient in food production. Since the irrigation water taken up by the plants had been consumed during the photosynthesis process, that part did not return to the river system. Therefore, the multiregional river depletion phenomenon developed. Two cases have been discussed internationally: the extensive lowering of the Aral Sea and its massive ecological consequences, and the drying up of the downstream part of the Yellow River, where one could walk across the river seven months a year in 1997. But the river depletion phenomenon is widespread, covering 15 percent of the continental land area.
The International Water Management Institute (IWMI) has introduced the concept of basin closure for this phenomenon. In the river basins concerned, all water is already being put to use, so that further water requirements can only be met by reallocation between users and uses. The fact that this phenomenon is expanding in a period when population growth is continuing in the low latitude countries, and hunger alleviation is a goal, agreed upon by all state leaders at the Millennium Summit 2000, suggests a very serious dilemma. It has now been estimated that by 2000, 1.4 billion people were living in closed river basins (as defined by a rough proxy of more than 70 percent use to availability). Out of these, 1.1 billion lived in basins where chronic water shortage was already severe. Another 180 million lived in closed basins where severe water shortage was approaching (more than 600 people per unit of river flow in million cubic meters in annual recharge).
In addition to the river depletion problem, a groundwater shortage has developed in the same regions. Groundwater use in agriculture has grown exponentially in scale and intensity over recent decades. As the competition for surface water has increased and posed constraints on farmers, many have turned to groundwaterâ€”the hidden, much more reliable water resource that already exists under their own land. The availability of water in aquifers is theoretically much more stable than that of surface water, which is delivered in irrigation schemes where those in the top end of the canal system easily get more water than do the farmers at the tail end. With a well of his own, the farmer is no longer dependent on such an inequitable system.
All over Asia, the history of well irrigation goes back for millennia. Globally, water withdrawals have grown from roughly 100â€“150 cubic kilometers (km3) per year in 1950 to almost 1,000 km3 per year in 2000. Most of this growth is concentrated in agriculture and often facilitated by cheap, subsidized pump electricity. Water policy scholar Sandra Postel has suggested that roughly 10 percent of the worldâ€™s food production may in fact depend on a yearly overdraft of groundwater. IWMI senior advisor Tushaar Shah and colleagues report that there are 19 million wells in India, 500,000 in Pakistanâ€™s Punjab province, and 3.3 million in the North China Plain. In some areas in Indiaâ€”North Gujarat, Tamil Nadu, and southern Rajasthanâ€”the bubble is about to burst. Although many farmers seek relief through rainwater harvesting to get more water to their crops, farmer suicides are in fact increasing in number as family economies are destroyed by loans to deepen their wells that cannot be repaid after bad years.