Olifants Dam Causes Ecology Headaches
HOEDSPRUIT (Kruger Times)- In June the Department of Water Affairs and Forestry (DWAF) announced further details of the second phase of the Olifants River Water Resources Development Project, which involves the raising of the dam wall on the Flag Boshielo Dam by five metres and the construction of the new De Hoop dam on the Steelport River, a tributary of the Olifants River.
Environmental impact assessments are being carried out for the project as announced at the beginning of June, and the Kruger National Park’s rivers department and the Olifants River Forum has met with other interested and affected parties to voice their concerns.
According to the KNP’s River Manager Dr Thomas Gyedu-Ababio, the park has submitted several concerns to the environmental impact agency, in the hopes that they can be mitigated during construction. Most of the concerns related to the changes in water quality that can be expected after the dam is constructed.
Gyedu-Ababio said that irregular releases of water from the dam could adversely affect the living creatures in the Olifants River system. Animals in the river have a physiology adapted to a certain flow rate, and surges and dips in the water volume can interfere with their lifecycles.
He also said sedimentation of the dam, and the subsequent release of silt when sluice gates are opened can harm the fish in the river. Fish in the Olifants River in the park already face problems when the sluices at the Phalaborwa barrage are opened and silt rushes out. The silt can not only cause immediate fish deaths, but it also alters the river bed and habitats may be lost for both fish and invertebrates. The bigger the dam, the larger the impact that can be expected downstream.
Dr Gyedu-Ababio also said that if the dam is planned without suitable fish ladders, those fish species that migrate upstream during their lifecycles will be compromised.
Other concerns related to the fact that dams can act as a reservoir for nutrients and heavy minerals, as well as alien species. When the dam sluices are opened, these are released and will flow downstream towards the Kruger Park, where they will have knock-on effects. Recreational activities on the dam can also introduce pollutants into the water.
Dr Gyedu-Ababio said that it was important that communities that live on the banks of the dam are educated about the importance of water, and how their activities can impact those downstream.
On the positive side, he added that if the dam is constructed and the reserve of the Olifants River is properly determined and then implemented, this could benefit all downstream, as they could be sure of a constant minimum supply of water.
The initial proposal for the De Hoop dam showed that the dam should yield about 90 million cubic metres of water a year, and cost about R1,000 million. The dam wall would be about 70m high, and the water is estimated to cover about 1600ha of land.
One of the tasks of the environmental assessment is to ensure that the size of the dam allows it to meet the downstream requirements of the water reserve, and not just the proposed water extraction targets.
The Olifants River Water Resources Development Project is not restricted to the construction of the De Hoop dam and the raising of the Flag Boshielo dam wall. It also includes extensive bulk water distribution (300km of pipelines), five reservoirs and pumping stations. Water will be used not only to expand the largely platinum mining activities in the area, but also to provide drinking water to many of the poor local communities.
Some water is also expected to be piped to the Olifants/Sand Transfer scheme that provides water for Polokwane, and a branch pipeline is planned for Jane Furse and the Nebo Plateau.
DWAF expect construction of some of the infrastructure to begin next year, and say that the De Hoop dam could provide full yields by 2011, subject to environmental approval. The project is expected to create extensive employment opportunities, directly through the dam building process, and also through the expansion of the mining industry.
A preliminary study was carried out last year that also looked at placing a dam directly on the Olifants River at Rooiport near Mafefe village, but the De Hoop site on the Steelport tributary was deemed to be the better option, both economically and in terms of water storage. There are already seven large dams in the Olifants River upstream of the Rooiport site, whereas this would be the first large dam on the Steelport River.
by Melissa Wray, Kruger Times
Environmental impact assessments are being carried out for the project as announced at the beginning of June, and the Kruger National Park’s rivers department and the Olifants River Forum has met with other interested and affected parties to voice their concerns.
According to the KNP’s River Manager Dr Thomas Gyedu-Ababio, the park has submitted several concerns to the environmental impact agency, in the hopes that they can be mitigated during construction. Most of the concerns related to the changes in water quality that can be expected after the dam is constructed.
Gyedu-Ababio said that irregular releases of water from the dam could adversely affect the living creatures in the Olifants River system. Animals in the river have a physiology adapted to a certain flow rate, and surges and dips in the water volume can interfere with their lifecycles.
He also said sedimentation of the dam, and the subsequent release of silt when sluice gates are opened can harm the fish in the river. Fish in the Olifants River in the park already face problems when the sluices at the Phalaborwa barrage are opened and silt rushes out. The silt can not only cause immediate fish deaths, but it also alters the river bed and habitats may be lost for both fish and invertebrates. The bigger the dam, the larger the impact that can be expected downstream.
Dr Gyedu-Ababio also said that if the dam is planned without suitable fish ladders, those fish species that migrate upstream during their lifecycles will be compromised.
Other concerns related to the fact that dams can act as a reservoir for nutrients and heavy minerals, as well as alien species. When the dam sluices are opened, these are released and will flow downstream towards the Kruger Park, where they will have knock-on effects. Recreational activities on the dam can also introduce pollutants into the water.
Dr Gyedu-Ababio said that it was important that communities that live on the banks of the dam are educated about the importance of water, and how their activities can impact those downstream.
On the positive side, he added that if the dam is constructed and the reserve of the Olifants River is properly determined and then implemented, this could benefit all downstream, as they could be sure of a constant minimum supply of water.
The initial proposal for the De Hoop dam showed that the dam should yield about 90 million cubic metres of water a year, and cost about R1,000 million. The dam wall would be about 70m high, and the water is estimated to cover about 1600ha of land.
One of the tasks of the environmental assessment is to ensure that the size of the dam allows it to meet the downstream requirements of the water reserve, and not just the proposed water extraction targets.
The Olifants River Water Resources Development Project is not restricted to the construction of the De Hoop dam and the raising of the Flag Boshielo dam wall. It also includes extensive bulk water distribution (300km of pipelines), five reservoirs and pumping stations. Water will be used not only to expand the largely platinum mining activities in the area, but also to provide drinking water to many of the poor local communities.
Some water is also expected to be piped to the Olifants/Sand Transfer scheme that provides water for Polokwane, and a branch pipeline is planned for Jane Furse and the Nebo Plateau.
DWAF expect construction of some of the infrastructure to begin next year, and say that the De Hoop dam could provide full yields by 2011, subject to environmental approval. The project is expected to create extensive employment opportunities, directly through the dam building process, and also through the expansion of the mining industry.
A preliminary study was carried out last year that also looked at placing a dam directly on the Olifants River at Rooiport near Mafefe village, but the De Hoop site on the Steelport tributary was deemed to be the better option, both economically and in terms of water storage. There are already seven large dams in the Olifants River upstream of the Rooiport site, whereas this would be the first large dam on the Steelport River.
by Melissa Wray, Kruger Times
Labels: conservation, dams, de hoop, olifants
posted by Kruger2Canyons.com at
Sunday, October 24, 2004
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