Completion of one of the biggest dams in the Middle East is anticipated later this year. Alan George and Tim Woods Ballard examine the critical role the Bassel al Assad dam will play in Syria’s overall water policy.
FOLLOWING the tragic death of Syrian President Hafez al Assad’s eldest son in a car accident, the former Khabour dam was renamed the Martyr Bassel Hafez al Assad dam. Situated on the Khabour river, a tributary of the Euphrates in northeast Syria, this structure looks set to become one of the biggest dams ever constructed in the Middle East.
The origins of the project can be traced back to the 1970s, when studies and designs were first prepared by the Bulgarian firm Agrocomplect. However, progress was blocked due to the acute currency shortages that Syria experienced throughout the 1980s. Slowly, financial matters began to improve and, in 1995, Syria’s Irrigation Ministry was successful in securing funding from the Kuwait Fund for Arab Economic Development (KFAED). Britain’s Gibb Ltd was appointed to review the old Bulgarian designs and the firm was subsequently retained to provide assistance with construction supervision. The main construction contract is held by the state-owned RIMA company, and the Irrigation Ministry’s General Directorate for Tigris and the Khabour basin (GDTKB) is overseeing the scheme.
Located 25km south of the town of Hasakeh, the dam will store 605 million m3 of water in a 92.5km2 reservoir. Twenty metres high with a crest length of 5km, the dam will form part of a wider programme to develop the Khabour valley’s agricultural wealth; permitting a major expansion of irrigation.
During construction, a particular problem of the site has been the prevalence of soils and bedrock with a high gypsum content. Such materials dissolve in water, which has caused subsidence at some other irrigation schemes in the Euphrates basin. To rectify this all materials with a gypsum content exceeding five per cent were excavated; a task which was completed in mid 1996.
The dam itself has a central core of clay with gravel shoulders. Beneath the core a 30m deep cement/bentonite wall has been built to reduce seepage. On the right abutment, the dam has been extended for a further 3km in the form of a clay-filled cut-off trench intercepting gypsiferous foundation rocks.
Final completion of the dam is anticipated some time this year. At the present time, the main embankment is almost at its full height, and construction of the low-level outlet works has been completed. The higher level works are undergoing final commissioning, as are the water intake structures for the main irrigation canals. (Each of these will be served by a pumping station to feed water to two high-level canals.) Construction of the spillway weir (located on the dam’s left flank), a downstream channel and the stilling basin are all essentially complete.
Although not entirely finished, the dam is already partially in use. During the 1996-7 winter about 50 million m3 of water was impounded. As the Khabour’s level was significantly below normal during the spring and summer of 1997, the impounded water proved to be of critical significance to farmers downstream of the dam, GDTKB’s head engineer, Adnan Merza, said.
When full, the reservoir will inundate about 8200ha of agricultural land, of which about one-quarter is presently irrigated by pumping from the river while the rest is rain-fed. About 30 000 people living in the area will be resettled immediately into new locations, supplied with all services and compensated for the loss of their houses and agricultural produce. Main roads on either side of the valley meanwhile will need realigning to take them beyond the inundated area.
Bids are expected soon relating to the development of farmland to be irrigated from the dam. Presently, these areas, extending to the town of Sur in Deir az Zor Governorate, are cultivated using water pumped directly from the river and from wells, but both sources are unreliable and can sometimes be of poor quality.
After a difficult period, during which hard currency shortages forced Syria to delay badly-needed development schemes, agriculture in the Khabour valley is at last being brought closer to its potential. This dam comes at a fortuitous time, just when flows in all Syria’s most important rivers are falling. This is due to increased rates of abstraction in Syria and, in the case of the Euphrates, Tigris and Khabour, increased water use by Turkey, when the river levels rise.
Ultimately, the Bassel al Assad dam will prove to be a critical element in Syria’s overall water balance.