Jebel Awlia Dam

By Eng. Hassubu-Annabi Musa Mohammed

(The Assistant Resident Engineer of the Jebel Awlia Dam)
Reference: pp. 20-21, ElMouhandis,Vol. 2, No. 5, December 1996 (in Arabic)
Translated by Dr Yousif H. Ahmed

Introduction:

The construction of Jebel Awlia Dam was funded by Egypt in 1933-1937 to cover its water demand in the summer. By 1959, after the signature of the Nile Waters Agreement between Sudan & Egypt, and consequently the construction of the Aswan High Dam, there was no Egyptian need for Jebel Awlia Dam. According to a special protocol, the management of the dam was transferred to the Sudanese Government on 28/2/1977. The functions of the dam are summarised as follows:

The increase of the area of the White Nile agricultural projects, in front of and beyond the dam, that allows the Sudan to maximise its benefits from the Nile Waters Agreement.
The dam lessens the danger of floods on the capital Khartoum and other northern areas; this is achieved by the storage during the flood periods of the Blue and White Niles.
The dam acts as a barrier against the spread of the harmful Nile weeds from south towards the north. This involves the collection and destruction of these weeds. It is known that these weeds reproduce very quickly and increase the evapo-transipiration.
The dam has a water-lock for ships to pass through the dam structure. This facilitates the transport of goods and petroleum between Khartoum and Kosti & Malakal ports. Also, it facilitates the movement of fishermen.
There is a water passage for fish migration from north to the southern parts where their reproduction areas.
The dam acts as a bridge between the two banks of the White Nile.
The dam represents a recreation and journeys destination for Khartoum’s residents.

The dam operation is usually optimised to serve the above functions, as well as, to carry out the yearly maintenance works.

Facts about Jebel Awlia Dam:

Full capacity of the dam	3.5 Milliards cubic metres
Length of the lake at full capacity	629 kilometres (up to Mallot)
Surface area at full capacity	1700 square kilometres
Water level at full capacity	377.5 metres (above the sea level)
Length of the concrete-dam	1693 metres
Length of the earth-dam	3305 metres
Total length of the dam	4998 metres
The height of the concrete-dam	22.0 metres
Number of the dam gates	50.0
Dimension of the dam gate	3.0 (width) * 4.5 (height) metres

The Dam Management:

The balance is carried out every morning to determine the dam gates for passing the water through, in accordance with a predetermined programme. There are three major balances that are carried out yearly, these are:

The first storage (372.5-376.5 m) starts at about mid July to raise the water level to 376.5 which is required for operating water pumps along the White Nile basin.
The second storage (376.5-377.4 m) ends normally by the start of October after raising the water level to 377.5 m. The 376.5-377.4m is the maximum water level required for maintaining bridges on the White Nile operational.
The reduction of the lake level (377.40-372.5 m), which is required for carrying out the maintenance work, starts by the mid of March and continues up to the 20th of May.

The Wind Effect on the Lake Level:

The huge area of the dam lake and its large width (which reaches up to 7 km in some areas) make it prone to wind effect that changes the water level between plus or minus 0.3 - 0.4 m. This results into two water levels at the dam front; one is artificial which appears on the dam butrusses, and the other is real which is deduced from the profile drawn from different water levels recorded at several gauging stations along the lake banks.

The Dam Maintenance:

The major maintenance of the dam commences by the mid of May (after reducing the water level to its lowest value) and finishes by the end of June yearly. There are three types of maintenanceworks that are carried out, in turn, once over a period of 3 years, these are:

Phase 1- which involves the drying and complete maintenance of the water-lock for ship transport.
Phase 2- which involves the maintenance and painting of half the number of the dam gates (No. 1-25).
Phase 3- which involves the maintenance and painting of the other half of the dam gates (No. 26-50).

Hydropower Generation:

The National Electricity Corporation (NEC) is commissioning a study to produce hydropower from the ten western closed dam gates. The study is carried out by Mertz & McLillian firm as part of the Hydropower from Dams Extensions Project. Also, geophysical and geotechnical studies have been carried out by the General Corporation of the Geological Research on behalf of Mertz & McLillian and Sir Alexander Gibb & Partners.

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