COMPLETED DETAILED DESIGN OF SIDI NACEUR DAM IN EL BAYADH WILAYAT IN ALGERIA

JSC Energoprojekt Hidroinzenjering successfully completed contract: Study of Detailed Design of Sidi Naceur Dam in El Bayadh Wilayat in Algeria. The subject of the contract is preparation of Detailed Design with tender documentation for construction of Sidi Naceur Dam in El Bayadh Wilayat. The Client is the Ministry of Water Resources, National Agency for Dams and Transfers (ANBT), a client that Energoprojekt Hidroinzenjering has a long-standing cooperation with on business activities in the field of water management. All contract phases have been realised in compliance with strict conditions which the Client, National Agency for Dams and Transfers (ANBT), defined in the contract.

Sidi Naceur reservoir is a multi-purpose reservoir which is to ensure potable water supply for municipalities of Brida and Haj El Mechri (Wilayat Laghouat), as well as irrigation of the plots in Wilayat Laghouat and El Bayadh, since agriculture is the predominant occupation of the inhabitants of this part of Algeria.

The integral Sidi Naceur reservoir in Sidi Naceur system is formed through construction of dams with three dam site sections (main Sidi Naceur dam of roller-compacted concrete, as well as additional embankment dams Shaba Sauh Shish and Tiskrin), while the reservoirs formed by these dams are interconnected with a channel (Figure No. 1).

Main dam on Sidi Naceur River and additional dams Shaba Sauh Shish and Tiskrin, with the crest on level 1,187.00 masl, will form an integral reservoir with a total volume of 36.16 million m3 on the normal pool level of 1,180 masl. Bearing in mind that the primary goal of Sidi Naceur reservoir is provision of water for water supply and irrigation, water intake is designed on the section  of the main dam Sidi Naceur. Apart from that, water intake is enabled for users in the section of additional dam Tiskrin.

Main discharge facility of Sidi Naceur system is located in the central part of main dam Sidi Naceur and consists of the spillway of a practical section (“USBR with vertical upstream face“), with stepped spillway and stilling basin (Figure No. 2).  Dam spillway is centrally positioned, with ten 13.0 m wide spillway bays and crest on level 1,180 masl. The width of bridge pillars between spillway bays is 2.0 m, so the total width of the spillway is 148 m. Stepped chute is connected to the downstream side of the spillway. Stilling basin (“USBR type II“) is provided for stilling of spill water. At the end of the stilling basin is toothed bumper wall and further downstream is coarse rip-rap.

In accordance with defined phases of Sidi Naceur contract implementation, apart from the full service on preparation of design documentation successfully realised in the previous period, the accent falls on the part of the task related to hydraulic model testing for the purpose of checking whether the designed technical solution ensures safe water discharge at full flow range.

Hydraulic model testing has been carried out in the hydraulic laboratory of the Institute of Hydraulic and Environmental Engineering of the Faculty of Civil Engineering, University of Belgrade. Testing of the main discharge facility of Sidi Naceur dam is carried out on the physical model with length ratio of 1:33, with adherence of Froude’s Law of Similitude. One section (by the length of the flow) is modelled on a scale model (Figure No. 3).

Hydraulic model testing of the adopted technical solution of the main discharge facility of Sidi Naceur dam showed that such solution, with suitable maintenance, enables safe water discharge at a considered flow range. Within the tests conducted on a scale model, it has been established that the capacity of the spillway is satisfactory and that the designed height of divide walls of chute is sufficient to receive the flow of air-water mixture. The tests showed that the flow in the stilling basin is stable and height of divide walls of the spillway, for low water level specified in the design is sufficient to withstand a surge without the risk of overflowing of the walls of stilling basin. Measured speeds at the bottom downstream from the stilling basin show that, at calculated flow rate of Q0,01% = 3.708 m³/s the intensities that could move and damage the designed stone protection do not occur.

Based on all performed model tests and calculations, at this phase of preparation of Detailed Design of Sidi Naceur dam, it has been concluded that the proposed technical solution of connecting channel and spillway on main Sidi Naceur dam enables safe discharge of flood water Т=10 000 and Т=1000 years.

In accordance with the conditions of contract and precisely defined phases of implementation, designer prepared environmental impact assessment study for adopted technical solution of Sidi Naceur system, as well as the study of the risk on the downstream section in case of dam failure. Apart from this, a cost-effectiveness analysis has been carried out, as well as the study of anti-erosion works in the catchment area.

Since all the phases of implementation of Detailed Design have been successfully completed, we expect that the investor, as the Client will as soon as possible issue an international tender for construction and supervision of the works on realisation of Sidi Naceur system.