Water for all

Natural History, July-August, 2003 by John Tanton

In her review of two books about Earth's supply of freshwater, Sandra Postel ["Hydro Dynamics," 5/03] writes of the need for a program that "fairly allocates the available water among all the parties." She speaks of a lasting Mideast peace depending on a "more equitable apportionment" of water between Israel and its neighbors; cites a UN convention calling for "equitable and reasonable use"; and warns that for most of the world's 261 rivers shared by two or more countries, "there is no treaty that divides the water equitably among all the parties."

But what is fair and equitable in the distribution of water? The same amount per capita, regardless of a country's total population? The same amount per country, regardless of the number of users? Should distribution be proportional to surface area, or should the country where the headwaters lie receive a greater share? Once set, should allocations stand for all time, or should they be renegotiated as population and other factors change?

John Tanton

Petoskey, Michigan

SANDRA POSTEL REPLIES: There is no magic formula for achieving an equitable apportionment of water among users of a shared river or aquifer. Many conditions must be factored into the calculations, such as climate, hydrology, population, existing and potential uses of the water, and the availability of alternative sources. It's up to all the parties involved (perhaps with help from an outside mediator) to hammer out a treaty that all will sign. Sometimes that may entail sharing the benefits of the river (irrigated crops, hydroelectric power) rather than fairly allocating the water per se.

Ideally, water treaties will be resilient. A good example is the treaty signed by India and Pakistan in 1960 to share the Indus River. The treaty took twelve years to negotiate (facilitated in the final nine years by Eugene R. Black, then president of the World Bank). But despite two subsequent wars and ongoing tensions between the signatories, the treaty has survived.