Tugwi Mukosi Dam Design Attributes and Ancillary works

The Tugwi-Mukosi Dam is a concrete-face rockfill dam, with a total height of 90,3 m (296 ft) and a storage capacity of 1.803 billion cubic metres.

What Is a Rockfill Dam?

A rockfill dam is a type of dam that is made from rocks and concrete. It is different than other types of dams because it uses a material called fill instead of water to create its structure. This fill is made from earth, gravel, and rocks that are excavated and then placed in the dam. The dam is then filled with water, and the structure forms as the water levels rise.

Features Of the
Tugwi Mukosi Dam

The dam comprises an upstream concrete face and twin drop-inlet structures excavated into the rock of the abutments; inlets serve as the dams’ spillways. These two spillways are located near the left and right abutments and direct water to a concrete-lined outlet tunnel which is 6 metres in diameter and 200m long.

Water is released into a riverbed through 2 metre diameter steel pipelines at a discharge speed of about 1090m3 of water per second. A dedicated plunge pool was introduced by the Salini Impregilo team to increase and guarantee stability and safety of the dam toe. Each intake tower is 35 metres in height, fitted with grilles that direct water to a 6 metre diameter concrete-lined tunnel (350m long) excavated along the left abutment.

Similarly, the outlet is comprised of an upstream intake structure and a pressure tunnel connected to a gate shaft just after the crest of the dam. The tunnel also has a diameter of 6 m.

Figure 10: Pictorial views of gate shaft and outlet pipes

From the gate shaft, 2 by 2 m diameter steel pipes connect through a dry tunnel to the valve

house that is situated downstream of the dam. During the construction of the dam, this outlet tunnel served as a diversion route of the water. (Mavhura E.2020).

 5 saddle dams have been constructed on the right bank of the main dam. The saddle dams are earth-fill structures, 20metres tall and 133metres long, with a clay core and a total volume of about 1 120 000 m3. The last dam has an auxiliary spillway.

Tugwi Mukosi Dam Finishes

Crest parapet walls that incorporate dam finishes including concrete paving, crest driveways, and handrails have been added to the dam.

Figure 11: Pictures of handrails and pavements at Tokwe Mukosi Dam.

Materials Used to Complete the Tugwi Mukosi Dam

Materials used for project completion and some additional features are provided in the table below.

Main Dam Excavations1,390.505 ㎥
Main Dam Backfill2,927,624 ㎥
Saddle Dam Excavations663,300 ㎥
Saddle Dam Backfill1,120,000 ㎥
Concrete Materials95,000 ㎥
Iron & Steel Materials4,500 tons
Waterproofing Layer8,542 m
Embankment Volume2,437,00 ㎥
Flood Design1 in 2000 years

According to Zimbabwe National Water Authority (ZINWA) construction standards, the Tugwi-Mukosi Dam was designed to have:

The Benefits of The Tugwi Mukosi Dam

Learn more about the many benefits of the Tugwi Mukosi Dam to local communities.

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