Matsoku Weir and Transfer Tunnel to Katse
Another means of increasing Katse reservoir's supply level and the efficient transfer of water to South Africa, the Matsoku Weir and Tunnel, will divert a maximum of 55m3/sec into the dam, so increasing the yield delivered to South Africa by a maximum
of 2,2m3/sec.
A base flow of 600 litres/sec will continue down the river at all times, with water only being diverted during periods of peak flow. It is expected to be in operation by the second half of 2001.
The Matsoku Tunnel is 5,6km long, and is being constructed using drill-and-blast techniques to maximise employment for local Basotho labour. It is being lined with 75mm thick steel-fibre reinforced shotcrete. A slight downhill gradient towards Katse ensures that the facility will be gravity-fed.
The weir, 180m long and 20m high, is a solid mass (21 000m3) of concrete. Water is directed by an in-stream ledge towards a fore-bay on the left side of the weir (on picture above). Here, the base flow passes through while the excess water enters the tunnel.
The weir's downstream face features a series of large steps, designed to dissipate the energy of water overflowing the weir.
The construction contract was due to be completed by April 2001.
