. . . LHDA dismisses dam wall safety concerns
BY LAWRENCE KEKETSO
The Lesotho Highlands Development Authority (LHDA) has clarified and defended its publicised decision to close the Mohale tunnel feeding into Katse Dam. The decision, which had raised some concerns on tourism viability as well as the safety issues around the dam infrastructure, has been explained by the Authority’s to quash any suspicions in what he called mandatory systems management of the project for long term attainment of good results. “We understand fully expectations regarding tourism attraction when the dam overflows, but we have to first satisfy the environment and water transfer mandate of the Treaty,” explained the CEO, Tente Tente.
While conceding the rare event of Katse Dam overflowing will be a spectacle not to be missed, he also reminded the public that since the project runs a system of infrastructure for a number of objectives, it should be taken into consideration that the Mohale dam water level has been at the lowest for a long time. It would therefore be more reasonable to allowed to also allow Mohale Dam to fill rather than release its water to satisfy other needs not necessarily in the mandate.
“We would definitely love to see the Katse overflow. This will happen naturally when the time comes but why not satisfy the need of maximising the water levels at both dams while also allowing the expected natural downstream flows before we can satisfy the tourism sector?” he asked insisting there is no other reason why the decision was called off other than what the LHDA explained.
While acknowledging that there could be some safety concerns raised, he was confident that the dam’s system management was alert at all times, which was the main reason why there was a permanent office at the site for management, monitoring and other functions.
The LHDA had earlier issued a media release that clarified requirements for effective operations of the dams, stating that during the recent periods of drought, the water levels in the dams went as low as below 15 percent of the live storage. The period between September and November 2019 was one such bad patch, the LHDA said, pointing out there was a lot of anxiety regarding future water transfers and the ability to generate electricity.
“It was thus a great sense of relief to witness the recent good rains and see the water levels in the dams rising. The prudent and correct approach to optimally operate the water conveyance system is, therefore, three-pronged, namely; (1) to maximise storage of the water in the system; (2) to ensure safety and structural integrity of the Dam walls; and, (3) to ensure that the needs of the environment downstream of the dams are catered for,” LHDA outlined in the statement. This was precisely how the LHDA responded in taking advantage of the opportunity presented by these good rains, the Authority said.
It further explained that LHWP Dams are operated as a system and not individually and the Mohale Tunnel was closed to prevent spillage at Katse Dam while there was still capacity to store more water in Mohale Dam. “This is in line with the provisions of the Treaty, which is to maximise the amount of water stored in the dams and to ensure that the yield of the system is maintained and sustainable,” the statement added.
It also outlined that the heavy inflows and the resultant rapid rising of the water levels in the Katse Dam prompted the LHDA to also increase the release of water into the downstream environment, stating in terms of the Environmental Flow Releases (EFRs) a certain percentage of the water entering the dams (inflows) has to be released downstream.
The releases are adjusted daily, however, this target of downstream releases was not always achieved through the continuous release of water through the compensation outlet, which continuously releases water into the river downstream. “As a result, a deficit accumulates over time. This deficit in releases has to be reduced by releasing high floods through the sluice gates during the period of heavy rains and high flows into the dams. These are called freshets,” explained LHDA in the statement.
LHDA was able to release the freshets as per the agreed operation guidelines by the Parties to the Treaty. The Authority further clarified that all of the above are fundamental to the good management of water resources and the project’s primary mandate as codified in the Treaty. As a result, the agreed purpose of the project cannot be compromised or prejudiced to satisfy other expectations.
“The dam is designed to spill/overflow when natural conditions together with other operations modes are suitable. Spilling of the dam heavily depends not only on the number of inflows over and above what the project stores in the dams for continuous water transfer and hydropower generation purposes but also over and above the mandatory environmental flow releases downstream.
“It is also important to note that, LHDA does not control the amount and timing of rains. As a result, the spilling of Katse Dam or any other dam cannot be purposely designed to coincide with a particularly preferred timing,” the statement concluded. Several engineering concerns had been raised following the release of the statement by the LHDA from avoiding to put the Katse dam to its full engineering test, to panic response from the effects that were witnessed about a decade ago when the floodgates were put to their full high pressure test.
According to some engineering sources closer to the dams’ operation and management, the current rains bring an opportunity for the might and engineering feat to be put to its highest test. “It is important to see how the Katse dam performs at full capacity and if all the safety units are well functioning. We are not even talking about any risks now, but an important juncture of the project to prove its engineering worth,” said one local engineer who asked to remain anonymous.
He also believes that the dam safety should be put under the spotlight in terms of possible rock saturation and possible landslides if Katse dam is spilling at full capacity.
“I am not even suggesting there is anything negative that can happen; maybe it is just the curiosity to prove the engineering marvel that Katse Dam,” he said. The Lesotho Highlands Water Project (LHWP) is a multi-phased, multi-billion Maloti project between the governments of the Kingdom of Lesotho and the Republic of South Africa.
In terms of the 1986 Treaty, the purpose of the LHWP is covered under Article 3 of the Treaty, basically, it is to enhance the use of the water of Senqu/Orange River by storing, controlling the flow of the Senqu River and its effluents to effect the delivery of specified quantities of water to the Republic of South Africa and to utilize such delivery system to generate hydro-electric power in Lesotho. The Treaty states that without prejudice to this purpose for the Project namely, water transfer and electricity generation, each of the two Parties to the Treaty has the opportunity to undertake ancillary developments in its territory.
These ancillary developments include irrigation, generation of hydroelectric power, development of tourism, fisheries and other projects for economic and social development. In implementing the Project on behalf of the Parties, the Lesotho Highlands Development Authority (LHDA) seeks to implement, operate and maintain the Project as efficiently and effectively as possible to meet the purpose for which the Project was established.
The Project not only contributes through employment creation, business opportunities for companies, skills development, revenue for the fiscus, generation of electricity to replace expensive imports but also, the construction of the dams and their associated infrastructure that include high-quality roads and accommodation facilities have been instrumental in the promotion of tourism and growth in hospitality-related services and products. These tourism and hospitality products services have a direct boost to local spending, hence inclusive growth and a trickle-down effect on the economy.