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The Disi project

August 16, 2008

After decades of starting and stalling, the Disi water conveyance project is finally being implemented. In essence, the project is a pipeline to pump about 100 million cubic meters of water from the Disi aquifer in southern Jordan, near the Saudi Arabian Border, to an increasingly thirsty Amman.

The Disi aquifer is a shared sandstone aquifer split between Jordan and Saudi Arabia. The water is of excellent quality, and until now, the water has been exploited by both sides for agricultural purposes, with some being used to supply the city of Aqaba. Debate over expanded use of the resources was centered on the following issues:

  1. The use of water in Saudi Arabia. This was (and still is, to a smaller extent), used to plant wheat in the northern Saudi desert. The perceived wasteful use of water in an enterprise that is not economically viable has encouraged Jordan to grab as much of the water while it lasts (More on the conflict here).

2. Cost. Much of the delay in implementation of the project was attributed to negotiations over cost with the contractor. Since the BOT model was used (because the Jordanian government didn’t have the cash at hand), this meant that the cost of implementation and operation would reflect on the cost of water when it reached Amman. Duraid Mahasneh has argued that it would be more viable to encourage people to move south that to pump the water to the north.

3. Sustainability. Because the aquifer lies in the desert, little recharge is expected to replenish the aquifer. Government spokesmen have suggested that the water will last anywhere from 50 to 100 years. Much debate has been centered around whether the aquifer consists solely of “fossil”, i.e., non replenishable water or whether there is a recharge component in the hydrological system. Study of stable and radiocarbon isotopes of the water suggests that the water is very old (over 25,000 years). Estimates of recharge volumes range from zero to 48 million cubic meters per year (out of a total stored volume of 6 billion cubic meters). This later number was obtained by Elias Salameh and Raja Gedeon, who used a robust technique known as the Chloride Mass Balance approach. While CMB is a good tool, it tends to overestimate rather than underestimate recharge values. While there is significant evidence that recharge is taking place in the area, little has been done to use this information as a marketing tool for the project. The implication is that the project may be more sustainable than the government is suggesting.

On the other hand, El Naser and Gideon in a 1996 IAEA technical document point out that there are different types of water in the Disi basin. There is low quality water in the so-called Khreim aquifer that overlies the good quality water in the Rum aquifer. While the paper does not express serious concern about salination of the Rum aquifer, it may be something to watch out for.

It is notable that more data about the hydrogeology of the Disi basin is not available. The issue of recharge, in particular, needs more scrutiny.

Anyway, the project is now upon us, for better or for worse. There are now two approaches to managing the new system. The first is to simply pump as much water as we can to meet increasing demands, and to leave the worrying over what to do later to future generations. The second is to try and manage the aquifer in such a way as to sustain extraction. This can be done by balancing recharge with extraction, and attempting to enhance recharge. This can be done by obtaining a better understanding of the surface hydrology of the area and determining where recharge tends to occur. We owe it to our children to try and adopt the second approach.

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