Thirst threatens with impending water crisis

Out of sight, out of mind has been the habitual stance taken by governments on the issue of groundwater depletion but overpumping of aquifers can no longer be disregarded. In 1999, the water table below Beijing fell by 2.5 metres providing an ominous warning that governments would be unwise to ignore. Today, some 40% of the world's food comes from the 17% of cropland that is irrigated. India, China, the United States and Pakistan together account for over half the world's irrigated land and many nations rely on irrigated land for more than half of their domestic food output. Indeed, in China, 70% of grain is currently harvested from irrigated land and, in Pakistan, 80% of all cropland is now irrigated.

China and Pakistan are not alone in facing water shortages. Other countries where water scarcity is increasing grain imports, or threatening to do so, include India, Iran, Egypt, Mexico, and dozens of smaller countries. The second World Water Forum held earlier this year (see Developments 00-3), raised the issue of future water security but it remains to be seen what action is taken by governments, and how quickly, in order to seriously tackle the global issue of overpumping and falling water tables.

Improving efficiency and simultaneously lowering water use will be necessary if future crop production is to be sustained. More than half of the water currently removed from rivers and aquifers for irrigated agriculture never benefits a crop, but technologies that are available will only improve water productivity if accompanied by good management practices. However, even with greater efficiency, farmers in the north of China are faced with loss of water from its diversion to burgeoning cities and industries. In the last fifty years, the number of cities in China has more than quadrupled and 50% of these are already short of water. Given the rapid urban and industrial growth north of the Yellow River Basin, it is predicted that irrigated agriculture could largely disappear by 2010, forcing a shift back to less productive rainfed agriculture. In June 2000, the Chinese government announced ambitious multi-billion dollar plans to take water by canal and pipe from the Yangtye north to Beijing and the farmlands beyond. The engineering challenges will be great and the environmental consequence unknown.

In Pakistan, the Indus Basin Irrigation System is the largest contiguous irrigation network in the world. It transcends all four provinces of the country and is of central importance to the economy. Unfortunately, the quality of irrigation service has deteriorated over time and charges levied on farmers for irrigation services are inadequate to meet operation and maintenance expenses. As a result, salinity and water-logging are spreading (30 and 20% respectively of total area of irrigated land), over-exploitation of fresh aquifers is widespread, and excessive use is being made of poor quality groundwater to the detriment of the soils and long-term agricultural productivity.

According to a recent study by Pakistan Water Partnership, the demand for water, which is already outstripping current water availability, is likely to increase by 48% by 2005, particularly as intensive cultivation and irrigation are likely to rise due to increasing economic pressures for commercialization. The water table is already falling by almost one metre each year in zones where recharge is not sufficient to meet demand. For example, in the province of Punjab, the country's leading agricultural region, groundwater is being pumped at a rate that exceeds recharge by an estimated 27%.

Besides constraining future food production, the overpumping of groundwater is widening the income gap between rich and poor as only the rich can afford to drill deeper wells, and buy and fuel larger pumps to lift the water to the surface. As shallower wells dry up, some of the small-scale, poorer farmers are forced into renting their land to the larger well owners and becoming their labourers. Populations in China and Pakistan, as well as India, Egypt, Iran and Mexico are estimated to increase by more than half by 2050. In these countries, where many people are already suffering from the effects of water shortage, the growth in population will sentence an increasing number of people to hydrological poverty with insufficient water to drink, to satisfy hygiene needs, and to produce food. Urgent strategic planning is essential if the looming crisis and its attendant human and environmental catastrophes are to be mitigated.

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