Three days after the fall of Egypt's president Hosni Mubarak, the then Ethiopian prime minister, Meles Zenawi, announced the start of construction of a dam on the Nile's main tributary. The Grand Ethiopian Renaissance Dam will be the first Ethiopia has built on the river. The move is a direct challenge to downstream Egypt's "hydro-hegemony", which had ensured that it and Sudan enjoy essentially exclusive use of the river, thanks to favourable colonial and postcolonial agreements.
Until 2010, Ethiopia, South Sudan and eight other states were negotiating water sharing under the auspices of the Nile Basin Initiative. These discussions have now degenerated into threats.
There is a similarly short-sighted dynamic occurring on the Tigris and Euphrates. Turkish plans to develop the primarily Kurdish south-east are centred on the Southeastern Anatolia Project - a series of 22 dams scheduled to be completed by 2023. Despite considerable resistance from Kurdish and environmental activists, about half the dams are complete, while the associated irrigation projects continue to create water shortages and salinisation for farmers downstream in Syria and Iraq. As in Egypt, the self-interested Turkish approach to international rivers will continue regardless of which party is in power.
Iraq faces a second problem as a similarly ambitious Iranian hydraulic development programme has started on the tributaries of the Tigris. Like their forebears thousands of years ago, the farmers in Iraq must now choose between eking out an existence on their land or moving to urban centres. The Iraqi government struggles to mount a diplomatic response, while the Syrian government clearly has its priorities elsewhere.
Rarely has water been so central to Middle Eastern geopolitics. But a war over water is unlikely; research has shown that power asymmetry and the relief valve of "virtual water" - a state importing food which it can no longer grow - are enough to counterbalance the risks. It is better to ask how cross-border tensions over unfair sharing of water can be reduced through the international norms that form the basis of sustainable water security policy.
These are not simply cases of non-Arab states capitalising on the unrest in downstream Arab states. All of the projects have been on the drawing board for decades. What makes the recent activity of such concern is the convergence of a number of factors: ideas of national development; increasing demand for water; and changes in the relative power of the states involved.
Upstream Ethiopia, Turkey and Iran are building the same infrastructure that downstream Egypt, Syria and Iraq built decades ago. All are propelled by the "hydraulic mission" mindset that governments from the United States to Australia have used to provide water and establish the consent of (or control over) people in distant provinces.
On top of this, growing populations boost demand for fresh water and food that must be met through either imports or irrigating crops. In turn, thousands of engineers are trained (as in Turkey and Iran) to meet that demand, which means more food production that opens up more markets - and lubricates a vicious cycle of unsustainable water consumption. Climate change might or might not be exacerbating water scarcity, but we should be clear about the root causes: man and states, not God or nature.
The people of Syria and Iraq will suffer the environmental, social and political consequences of dam building on the Tigris and Euphrates, just as Egyptians will suffer them on the Nile. Obstruction of the rivers means reduced biodiversity, reduction of the precious sediment transport downstream that rejuvenates fields, the submersion of areas of global cultural heritage and the displacement of villagers. None of these is taken lightly but the political consequences are of equal if not greater magnitude.
These will be felt first by the farmers who require much more water than the average citizen. Politically-connected industrial farmers can generate the funds to meet their water needs but smaller farmers are not so privileged. A reversal of fortunes has occurred in fertile Iraq, as people who used to sell vegetables to their local markets are now obliged to buy them from Turkey and Iran.
Under these circumstances, it is only a question of how and when - not if - the tensions of the water-poor countryside will reach the capitals, and from there play out into political tensions across borders.
The common point in each of these water conflicts is that the most powerful state has done its best to avoid establishing a fair trans-water-sharing regime. International water law - particularly the 1997 UN Watercourses Convention - details the customs agreed between states through the centuries, with "equitable and reasonable use" as the guiding principle. But the most powerful states have paid only lip service to these principles, or ridiculed them. This was most clear with the Mubarak government, which stonewalled on negotiations of the water-sharing clauses in the Nile Basin Initiative's Cooperative Framework Agreement. On the Tigris and Euphrates, the suggestion of guiding legal principles is a non-starter for Turkey.
Had the Egyptian or Iraqi governments sought equitable sharing when they were the more powerful state, their people might today have enjoyed the benefit of a fair and established water-sharing regime.
Now Turkey, Iran and Ethiopia face the same decision: unilateral development of a shared resource, or multilateral and sustained development based on international norms. We have seen how situations of unfair water sharing will endure only as long as the power asymmetry that allows them to develop in the first place. The fallout from these water conflicts can be avoided, but only once all parties agree to compromise for the common interest.
Mark Zeitoun is Director of the Water Security Research Centre in the School of International Development at the University of East Anglia, and author of Power and Water in the Middle East (IB Tauris)
The article originally appeared in Chatham House's magazine The World Today