Construction |
Powering progress
IWP&DC provides recent construction updates from various hydropower projects and dams across the globe
Above: Acciona celebrated one of the most important construction milestones of the Carén reservoir expansion project in Chile in May 2023: the topping out of the dam
WITH HYDROPOWER PRESENTLY CONTRIBUTING to more than 15% of the world’s electricity generation1
, it
is evident that the industry continues to play a vital role in meeting global energy demands. According to the 2023 World Hydropower Outlook
recently published by the International Hydropower Assocation, the current pipeline shows 590GW of hydropower projects at various stages of development, including 214GW of PSH. There is also significant potential for further power increases through refurbishment and expansion of existing projects. In terms of new construction, in late May 2023, Lesotho and South Africa celebrated a significant milestone as construction officially commenced on the main water transfer works for Phase II of the Lesotho Highlands Water Project (LHWP). The works include Polihali Dam, Polihali Transfer Tunnel and the Senqu Bridge. The sod-turning ceremony took place on 23 May in Malingoaneng Mokhotlong, attended by His Majesty King Letsie III and President Cyril Ramaphosa of South Africa. According to Tente Tente, the Chief Executive of the Lesotho Highlands Development Authority, the advanced infrastructure, including roads, bridges, power facilities, and housing, is almost complete, paving the way for the main construction phase. The construction of the dam and tunnel is expected to take about five years, with water transfer operations scheduled to start in 2028. The Oxbow Hydropower Scheme, an integral part of Phase II, will begin generating power in 2029. The Polihali Dam, similar to the Mohale Dam built during Phase I of the LHWP, will be a concrete-faced rockfill dam. It will create a reservoir across the valleys
46 | July 2023 |
www.waterpowermagazine.com
and tributaries of the Senqu, Khubelu, Mokhotlong, Moremoholo, and Sehong-hong rivers, covering an area of 5053 hectares. The dam will include a spillway, a compensation outlet structure, and a mini- hydropower station. The Polihali Transfer Tunnel will transport water
from the Polihali reservoir to the Katse reservoir using gravity. From Katse, the water will be delivered through a tunnel to the ‘Muela Hydropower Station, constructed during Phase I, and then channeled to the Ash River outfall outside Clarence in the Free State, ultimately supplying water to Gauteng. One of the notable features of Phase II is the Senqu Bridge, which is almost one kilometer long and stands 90m tall. This bridge, the first of its kind in Lesotho, surpasses the Mphorosane Bridge constructed during Phase I. It is the largest among the three bridges to be built under Phase II, spanning the Polihali reservoir. The Polihali reservoir will add 2,325 million cubic
meters of storage capacity to the LHWP, increasing the annual water supply rate from 780 million cubic meters to 1,270 million cubic meters. This expansion will help meet South Africa’s growing water needs. Additionally, the increased water flow will enhance power generation within Lesotho, reducing the country’s reliance on electricity imports. Phase II builds upon the success of Phase I, which was completed in 2003. Over in Pakistan, the Water and Power Development Authority (WAPDA) announced in early June that it is all set to divert the River Indus as part of the construction works for Diamer Basha Dam Project. The river will be diverted through an almost 1km-long diversion tunnel and 0.8km-long diversion canal
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