麻豆传媒

IMAGINE sharing scarce water with your neighbours without having any say in how long they shower or how often they run their washing machine. This is the situation many nations find themselves in when it comes to sharing out the 96 per cent of the world鈥檚 fresh water that comes from aquifers deep underground.

Many of these subterranean reservoirs straddle international borders. With the UN predicting that by 2025 two-thirds of us will experience water shortages, the blue gold they supply will become more valuable than ever. Yet there are no international rules to help sort out how to share this water.

That could be about to change. Last week, the UN General Assembly鈥檚 legal committee scrutinised a draft law designed to diffuse conflict over water resources by encouraging governments to use trans-boundary aquifers in an 鈥渆quitable and reasonable鈥� way. This is envisaged as the first step in a ground-breaking plan to lay down guidelines on how to share all the underground resources which can give rise to conflict when they straddle borders 鈥� including oil and gas.

Aquifers are porous layers of rock or sediment from which water can be extracted by drilling boreholes or digging wells. They supply about half of the world鈥檚 drinking water, 40 per cent of the water used by industry, and up to 30 per cent of irrigation water. Rivers provide most of the rest.

鈥淲e know a great deal about global river flow, and we know almost nothing about groundwater,鈥� says Richard Taylor, a hydrogeologist at University College London. This lack of knowledge, and the fact that aquifers are hidden from view, means that they can be over-exploited for years before the damage becomes obvious. The water level within the Ogallala aquifer, which stretches across eight Midwestern US states, has dropped by more than 35 metres in 50 years, for example. Where aquifers cross international borders, their invisibility can make the politics particularly complex, says Mark Zeitoun, a water policy expert from the London School of Economics.

Falling water tables can bring catastrophic ecological, economic and social consequences. Around the Mediterranean, seawater has begun seeping into aquifers, rendering the groundwater unusable unless subjected to expensive desalination. In China, water shortages resulting from over-exploited aquifers helped cause a fall in rice production from 140 million tonnes in 1997 to an estimated 127 million tonnes in 2005, according to the US embassy in Beijing.

Such damage will not quickly be repaired. 鈥淎quifers are not like rivers, it takes years for an effect to show,鈥� says Raya Stephan, an international lawyer with UNESCO. 鈥淪omething could be happening now that will have an effect in 10 years鈥� time.鈥�

鈥淎quifers are not like rivers: it takes years for an effect to show. What鈥檚 happening now may have an effect in 10 years鈥� time鈥�

The proposed new water law has been drawn up by the International Law Commission (ILC) as a follow-up to the still-unratified 1997 Convention on the Law of Non-Navigational Uses of International Watercourses, which dealt with the use of surface water. The complexity of the task is illustrated by an atlas of underground water sources drawn up by UNESCO, which was also published last week. The atlas identifies 273 trans-border aquifers, some spanning as many as four nations (see map).

It is situations like these that have prompted politicians to warn of impending water wars. If a shared aquifer is over-pumped by one country, its neighbour can suffer the consequences.

The Guaran铆 aquifer system, for instance, is a potential resource for some 15 million people in Brazil, Argentina, Uruguay and Paraguay. Near the Brazilian city of Santana do Livramento, on the border with Uruguay, sewage is threatening to contaminate the aquifer. A 2002 report from the World Bank backs an agreement between the four governments which aims to reduce 鈥渃onflict potential鈥� at sites like this.

The UN鈥檚 proposed water law would provide governments with a starting point when drawing up such agreements. 鈥淲e have frequently heard from water technicians who tell us that for aquifers they do not have anything to which they can refer,鈥� Stephan says.

Some of the largest untapped aquifers are in northern Africa. The Nubian sandstone aquifer, which contains 10,000-year-old 鈥渇ossil water鈥�, is shared between Egypt, Libya, Sudan and Chad, which have formed a joint authority to manage it. Their agreement makes no mention of 鈥渆quitable鈥� use, however, which as Stephan points out is one of the guiding principles enshrined in the UN鈥檚 draft law.

Prior notification is another key principle, which is already applied to river water. 鈥淚f Ethiopia wants to build a dam on the Nile, it must first inform Egypt,鈥� says Geoffrey Dabelko, director of the programme on environmental change and security at the Woodrow Wilson Center in Washington DC.

It is a principle that has been ignored in the past. In the 1970s, India built a barrage across the river Ganges to divert part of its water towards Kolkata, reducing the supply of water to Bangladesh a short distance downstream. This affected not only surface water but also the aquifers that are recharged by the Ganges, resulting in increased salinity and other contamination of the water. In the absence of any agreement, Bangladesh was forced to protest to the UN. 鈥淭hat proved very effective,鈥� Dabelko says, and India eventually signed an agreement under which it allows some flow to continue downstream.

One of the problems of sharing out water is deciding what proportion of a shared aquifer is 鈥渆quitable and reasonable鈥� for each nation to exploit. Should it be based on the number of people that depend on its water, the extent to which the aquifer lies within its borders, how much of the rain that recharges the aquifer falls on its territory, or some other consideration?

鈥淪hould a nation鈥檚 share of an aquifer be based on the number of people that depend on it, or some other factor?鈥�

All these factors are written into the ILC鈥檚 draft, along with the social and economic needs of each state and the role which the aquifer plays in its wider ecosystem. This has inevitably led to wording of the draft being rather vague, says Stefano Burchi, a legal expert with the UN Food and Agriculture Organization. 鈥淚t must reflect the interests of all involved, mountain states, island states, upstream states and downstream states,鈥� he says.

鈥淭here鈥檚 an urgent need to get water-sharing principles in place. Everywhere aquifers are being over-pumped,鈥� says Zeitoun, who advises the Palestinian Authority in its negotiations with Israel on how to share out water. 鈥淭he side with the deeper wells and better technology goes for it while the weaker side suffers.鈥�

It is, however, unlikely that the draft water law will become legally binding any time soon. In last week鈥檚 discussions, the UN committee favoured adopting its provisions as guidelines first, with the option of making them legally binding in the future.

There is sound precedent for being cautious about the likelihood of governments agreeing to legally binding rules. Though national delegations adopted the 1997 water convention almost unanimously, only 16 states have ratified it 鈥� and the convention will not come into force until that number rises to 35.

鈥淭he ILC鈥檚 special rapporteur was very concerned with the sorry fate of the 1997 convention,鈥� Burchi says. 鈥淗e did not want to fall into the same trap of setting an overambitious goal.鈥�

Ultimately, 鈥渢he effect of an international convention on tensions over water will be an indirect and subtle one,鈥� says Kerstin Mechlem of the University of Ulster in the UK. 鈥淭rans-boundary surface water resources teach us that tensions can persist despite an international legal framework. However, international law provides a basis of negotiations to ease tensions.鈥�

Whether or not the same can be expected of legislation on oil and gas sharing remains to be seen. The ILC is expected to kick off those discussions in March 2009.