Like most ancient civilisations, Mesopotamia flourished on the abundance brought by its two great rivers. The land between the Tigris and Euphrates was a wonder of the Ancient World, a cradle of agriculture where corn and vegetables, dates and fruits nourished the empires that arose on its soil. Even now, when most of Iraq's wealth gushes up from below the ground, agriculture remains crucial to the economy. But for the past two years Iraq's farms have been ravaged by a scourge as terrible as it was in biblical times: drought. Without water, all efforts to rebuild the country after decades of violence and war will come to little. The horrific suicide bomb attacks in Baghdad and Kirkuk yesterday deserve the world's attention - and sympathy. But conflicts over water could bring yet more tragedy.

Last winter Iraq received only about a third of its normal rainfall. Fields of winter wheat have withered, the wells have run dry, sheep, goats and cattle have died and farms have turned to dust. In Diyala province, traditionally the breadbasket north of Baghdad, the irrigation channels have dried up and the main reservoir holds less than 10 per cent of its capacity. People are digging wells but finding only brackish water, unfit for human or animal consumption. Thousands of farmers have fled their homes, joining about 2.8million internal refugees in Iraq.

Iraq's wheat and barley crop is expected to fall 50 per cent compared with last year. The country's oil revenue allows it to import grain and food from overseas, so the threat of hunger is not acute. But the drought poses other dangers. Hydroelectric plants stop working, exacerbating power shortages. Cholera has broken out where rivers are stagnant, wells low and the sewerage infrastructure damaged by war and neglect. Severe sandstorms have posed health hazards for the sick and the old, and have disrupted flights.

The drought also has international implications. The flow of the Tigris and Euphrates is greatly reduced, partly because Turkey and Iran have built huge new dams upstream for ambitious irrigation projects. Iraqi officials have held urgent talks with Turkey, which has promised to release more water, and Baghdad is offering to sell oil at preferential rates in return for water. Iran and Syria, however, also tap vital headwaters and neither has made concessions.

International agencies have long given warning of conflict sparked by competition for scarce water resources. Many of the underlying tensions between Israel and its neighbours or Turkey and the Arab south are related to quarrels over water. Drought, famine and conflict are age-old. But these threats have been exacerbated by climate change and population explosions. In developed societies, such as Australia, governments have enough difficulty persuading people to cope with water shortages. In countries such as Ethiopia and in southern Africa, drought can still kill people and animals in their thousands.

Iraq's water shortages are not yet critical, and a return of wet winters could ease the problems. But the Government should plan for the dams, wells, drainage and pipelines needed to deal with a continuing shortage. This is an issue that crosses tribal, sectarian and ethnic boundaries. A failure to deal with the drought, on the other hand, could reinforce them.