From: Philip Owen <email@example.com>
Date: Wed, 16 Mar 2005 12:24:46 +0200
Subject: Dam Threatens Kruger Gorge
Apologies for x postings.
This article evoked wide ranging response. It is a complex issue, with the management of the entire Olifants river system contributing to siltation problems.
A dam can be a damn bad thing. It obstructs the movement of sediments (and nutrients) which any river carries along with it. This disturbance to the natural cycles involved causes damage to the integrated environment which is not yet fully understood – certainly not comprehensively quantified.
Could the fact that most of the Worlds Rivers have been damned be responsible for the crash in global fish stocks? (Many fish spawn in estuaries and are dependant on the nutrients carried by the river).
Did you know that dams silt up an average of 2% a year – giving a dam an effective life span of a mere 50 years!
Did you know that many of South Africa’s dams contain more silt than water?
Did you know that there is no practical means of mitigating silt up of dams? Even specially designed sluices gets jammed solid by silt.
A symbol of progress? Yeah… Right….
Can we afford to damn this gorge?
This article appeared in the Kruger Times, March, 2005.
Dam Threatens Kruger Gorge
The small village of Massingir, about 330km north east of Maputo, is slowly shedding her rural leathers and garbing herself in urban feathers. The driving force behind the new electricity supply, more buildings, upgrade of the local clinic, school, even the waste disposal system and road network can be traced to the rehabilitation of the Massingir Dam. This is not perceived as good news all round.
The project has been met with diverse responses ranging from resistance to gratification, on both sides of the border.
In Mozambique, the government obtained an US$80million loan from the African Development Bank and assigned ARA-Sul (Administraco Regional de Aguas do Sul) as Executing Agent, under the chairmanship of the National Directorate of Water (DNA), to co-ordinate the rehabilitation of the dam and Xai-Xai smallholder agricultural project downstream.
DNA appointed the Project Implementation Unit (PIMU) to manage the various rehabilitation activities of the project. PIMU comprises two Component Implementation Units (CIUs) for the dam and the irrigation activities.
The Olifants River Forum, comprising stakeholders such as the Lepelle Water Board, the Kruger National Park, Palabora Mining Company, Sasol, Foskor, Eskom and other corporations with a stake in the river maintain serious concerns about the ecological impacts the dam will have on the river and its unique habitats, because of the scale of construction that is being undertaken.
The rehabilitation could lead to the destruction of sections of an 8km gorge that has no parallels elsewhere in South Africa. Though the South African and Mozambican governments seem well aware of these effects on the Olifants River gorge in the Kruger National Park, no interventions are apparently planned to prevent the destruction of this pristine and one-of-a-kind wilderness area.
The matter has been raised by conservation organisations like the Olifants River Forum, as well as at a workshop that was initiated by the Kruger National Park and held in Letaba last year, but there seems to have been a lack of coordination at the various sectoral levels that should have ensured consultation and consequent implementation of measures that would have prevented an ecological disaster to a national asset – Kruger National Park.
The upper sections of the Massingir dam, the second largest in Mozambique, is about 4km downstream from the eastern border of the Kruger National Park (KNP). It was built in the early 70s, in terms of an agreement between South Africa and Portugal, prior to South Africa’s current environmental and water laws, to ensure irrigation to the Lower Limpopo Valley in Mozambique and to possibly supply hydro-electrical power.
The Mozambican civil war hampered the final completion of the dam, notably the installation of the sluice gates. These are now being repaired and will be installed as part of the rehabilitation process. Rehabilitation also entails restoring the dam wall to enable the dam to carry its full reservoir of 2 800 million cubic metres.
The process around the initial Environmental Impact Assessment (EIA) of the Rehabilitation of the dam is confusing. It appears Kjell Essel of Norplan did an EIA for the Mozambican ministry of Industry and Energy and African Development Bank in 1993. Though the Kruger National Park is a primary interested and affected party, it was never consulted and neither has a copy of the EIA ever been made available to the Park for comments.
The Department of Water Affairs (DWAF) told the Kruger Park Times it could not trace the EIA either. Themba Khumalo, spokesperson, said a professional service provider has been appointed to do a further EIA at this time. “They would also make the terms of reference available to South Africa but it is still awaited,” says Khumalo.
The Department of Environmental Affairs and Tourism told the Kruger Park Times that it “shares a view that the rehabilitation of the Massingir Dam has a potential to cause ecological impacts on the Olifants River gorge in Kruger. This matter has been raised at the Joint Management Board and Ministerial meetings of the Great Limpopo Transfrontier Park initiative. In these meetings, Mozambique undertook to conduct an environmental impact assessment. Further consultations are underway regarding this matter to ensure that impacts on the KNP are mitigated.”
According to Dr Freek Venter, Head of Conservation Services in the KNP, there is no mitigation that could be done to save the Olifants River gorge.
“The dam will cause massive sedimentation in the gorge and even possibly as high as the Olifants Wilderness Trails camp, but there is no information available because no proper study has been undertaken. The sedimentation will destroy the deep pool-rapid ecosystem in the lower Olifants and Letaba rivers.”
”Once lost this national treasure cannot be regained. It will be lost for ever,” says Venter.
It is unclear how Dwaf hopes to mitigate the impacts as the rehabilitation is currently ongoing without specified intervention to ensure the gorge will not be destroyed.
On the Mozambican side, PIMU contracted specialists to identify, propose and implement mitigating measurements. These include fauna and flora, ecosystems, land issues, maintenance of watercourses and environmental mitigating measures during construction.
Marcus Wishart from Australia, has been doing different Environmental Impact studies on the dam and river on behalf of IMPACTO, a private company in Mozambique.
Douw Swanepoel, a crocodile expert, has been contracted by PIMU for baseline monitoring of wildlife in the Massingir area.
The wildlife assessment project comprises three basic phases – a census during the first year, correlation and verification during the second year and to monitor the impact of the dam when it is full during the last phase.
The rehabilitation will be finalised in October 2006 when the dam will be filled.
Floods and filling the dam
In their newsletter a year ago the Olifants River Forum stated its concern that when the Massingir dam is full, and it rises an additional 10m, the dammed water will push back into the gorge section of the KNP. During floods the water will push even further up the gorge, depositing silt. The inflow area of dams is where sediment is dropped when water flow reduces speed.
Two major floods of the Olifants River in 1996 and 2000 filled up deep pools in the lower third of the gorge with sand. What was previously a single, narrow channel with a large, slow flowing water body and deep pools, inhabited by large populations of fish and hippopotami, has been changed into a shallow, sandy stream.
The Massingir dam has already slowed water in the Olifants River in Kruger down, especially during floods, increasing the siltation of the gorge.
This has resulted in increased siltation within the lower third of the gorge. Almost all the deep pools in the lower part of the gorge were filled with sand, so much so that they have disappeared completely. It is now feared that the rest of the gorge and further upstream in the Olifants and Letaba rivers will be destroyed.
When the dam overflows, it is likely to back up the water even more, as the water rises above the crest of the dam wall. This will deposit sediment even further upstream than occurs when the dam is only partially full.
A build-up of siltation has already occurred in the upper reaches of the Massingir Dam itself where sediment has been deposited in a fan-like delta as a result of the flow rates decreasing due to the dammed up water. It can be expected that this process will continue.
According to the Olifants River Forum one mitigation option that was proposed is to operate the dam at a lower level than normal for several years to allow smaller floods to remove the sediment from the gorge. Unfortunately, due to the restricted release from outlet valves in most older dams, it is not possible to manage dams so that they have lower levels during extreme flood events.
The gorge section of the Olifants River differs completely from the rest of the 100km of river and all other gorges in South Africa. It has a deep, single thread, pool-rapid structure and is well known for its deep clear pools and prolific crocodile populations.
According to Swanepoel the initial indication show the major impacts will be on the fish, crocodile and hippopotamus populations in the river, and specifically, the gorge.
The fish population in the river has already been severely depleted with the number of dams (2500) in the river.
Crocodiles are prehistoric animals and “are some of the most adaptive species on earth,” says Swanepoel. He believes, as the dam fills the upper 1,5km of the gorge, the crocodiles will do one of three things.
“They will either stay in the remaining 3,5km of the gorge, or move upstream or into the Massingir Dam.”
He does not think it is likely the animals will move upstream due to the general condition of the river and believes it probable that they will move on towards the dam.
These studies are ongoing.
By: Lynette Strauss ( firstname.lastname@example.org )