Ngonye Falls Hydroelectric Project Design

The Design

The design is run-of-river which means there is no dam and no storage or water. A portion of the river’s flow is diverted for power generation and then immediately fed back into the river.

This means that downstream of the powerhouse the project has no impact on the amount of water in the river or on any other users of water.

The project does not include a dam or a reservoir (lake) it also has a very low environmental impact and produces almost zero greenhouse gasses.

However, as the project is run-of-river, it does not have the ability to store water (and therefore electricity) during times when the river is in flood. This means that extra electricity cannot be generated during drought periods.

For this reason the electricity generation from the project will be dependent on the amount of water flowing in the river at any given time.

Power Evacuation

An existing 66kV powerline passes within a few km of the project site. However this existing powerline cannot evacuate all the power generated by the hydro project.

A new 330kV powerline will be constructed to the substation at Sesheke and will form part of the planned Grid extension north to Lukulu (dashed green and purple).

ZESCO have transferred responsibility for construction of the 110km transmission line to WPC. It will be included in the EPC contract.


The headworks are a series of weirs and embankments and a concrete barrage which are designed to:

  • Hold the level of water upstream of the power station at a constant level of 990m above sea level.
  • Contain adjustable crest-level weirs that can be dropped to allow flood flows to pass (without causing significant flooding upstream)
  • Contain weirs to constantly pass the required Environmental Flow Requirements to maintain the ecology and habitat between the weir and powerhouse.
  • Contain fish passages to allow fish to pass up and downstream past the power station.


The headworks divert a portion of river’s total flow through the intake structure and into the power canal.

The headworks across the west (right) river channel include sections of adjustable Environmental Flow Requirement (EFR) weirs which allow constant flow of water and a number of fish ladders, structures to allow fish to migrate past the power station infrastructure.

The adjustable weirs can be raised and lowered to allow more or less water to flow past the headworks. The access road allows for maintenance of the adjustable weirs.

Canal and Forebay

The power canal carries water 3km from the headworks and intake to the powerhouse where the electricity is generated.

The power canal is 11m deep with a maximum water depth of 7m when filled to its capacity of 1,100 cubic meters per second of water flow.

The width of the canal, including its retaining embankments and access roads, is around 120m.

The canal is partially excavated into the terrain and lined with concrete.

At the end of the canal a forebay is formed from the natural landscape and retaining dams. The forebay holds a buffer of water for the power station to maintain constant flow through the turbines.

Powerhouse & Switchyard

The powerhouse contains the 4 identical 45MW bulb turbines and their generators which spin due to the action of the water and generate the electricity.

The powerhouse also holds the maintenance and control equipment needed to operate the power station.

The electricity generated is fed to the switchyard where the voltage is raised to transmission level (220kV) and the connection to the national transmission network is made.

The powerhouse is nearly 60m high but the majority of the structure is excavated into the river bank and so is not visible from the surface.