Design of the Quatabian Dam, Sulaymaniyah Governorate, Iraq 2009 – 2010

Type : symmetrical trapezoid shaped hardfill dam – CSG

Upstream side slope:1:0.7
Downstream side slope:1:0.7
Maximum Height:42.7 m
Maximum Base Width: 62.56 m (in toe of dam)
Crest Width: 10.6 m
Crest Length: 288 m
Crest Level: 1 017.20 m
Dam Body Volume: 270 000 cum
Catchment Area: 1 375 km2
Reservoir Area: 143.6 ha (at Elv. 1010 m)
Resorvoir Volume: 25.8 mil cum (at Elv. 1010 m)

Design net head :30,0 m
Design total discharge :10 cum/s
Designed unit :2x horizontal Francis turbines
Max. power output : 2x 1350 kW (on coupling)

Type: non-controlled crest spillway
Spillway lenght :120 m
Number of sections :10
Dam bridges :reinforced concrete monolithic
Bottom outlets :2x DN 1 600 mm

The project is located in the Northeast of Iraq in Sulaymania Governorate. The dam profile is located on the Siwail River 9 km  northeast of Chwarta near the village of Ashi Baram. The dam will be constructed in the catchment area of the Siwail River, which is the permanent stream with flow during all seasons. The watershed area belonging to the dam profile is 1,375.5 km2. The average discharge is about 5-7 m3/s. The Quatabian dam is a multipurpose project comprising storage, flood control, irrigation and recreational uses, according to the hydraulic design as an overflow dam. 

The dam body is designed as the symmetrical trapezoid-shaped type constructed from hard fill material (Cemented Sand and Gravel – CSG). The width of the dam is 61.40 m in the toe of the dam (spot height is 976.40 m a.s.l.). The crest of the dam at the elevation 1,017.20 m a.s.l. is 10.6 m wide. The length of the crest is 288 m. The downstream and upstream slopes are generally 1:0.7. The dam body is equipped with an upstream plastic sealing geomembrane – SIBELON CNC of CARPI system, fixed by artificial anchors to the upstream face of the dam body. The backside of the sealing is equipped with a flat drainage system handling seepage through the seal. The drainage outflow is directed to the inspection gallery and through the galleries out of the dam body. The spillway structure is designed as uncontrolled (no gates) (Scimemi faced) and is located at the dam crest. It consists of 10 sections each 12 m wide (separated by piers 1.50 m wide). The stepped chute (in the slope being 1:0.7m) is connected to the spillway to reduce the kinetic energy of water. The 0.6-m-high steps produce considerable energy dissipation along the chute and could reduce the size of the stilling basin, which is designed as a slotted bucket stilling basin with an 8° sloping apron on which teeth of 45° are installed. The design discharge is Q1.000 = 3,200m3/s and the kontrol flood discharge is Q10.000 = 4,700m3/s. The bottom outlet is placed in the left side of the valley. For the bottom outlet two pipes DN 1,600 mm are designed. At the beginning the intake tower and at the end the machine room with knife gate valves are designed. The operating armatures at the outlets from pipes will be fix cone valves (Howell-Bunger valves). These pipes will also serve as a diversion during the implementation period and they will be converted into the bottom outlet structure at the end of construction. 

A small hydroelectric power plant is incorporated into the Quatabian Dam Project and is located separately in the left side of the valley downstream the dam by the left bank of the tailrace channel to utilize the hydro-power potential of the planned dam profile. The powerhouse is equipped with 2 horizontal Francis turbines. Water is fed into the turbines by 2 separate pipelines DN1400 tapped to each of two bottom outlet pipes DN1,600 inside the machine room. The hydroelectric power plant is supplied by water from the water reservoir with a relatively high storage capacity which is primarily designed for irrigation of farmland.

More information here. 

CREA Hydro&Energy, z.s.

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