Kariba Dam Wall ZimbabweFrom : http://allafrica.com/stories/201303180564.html

The Zambezi River Authority yesterday opened two of the six flood gates for the dam to release excess water downstream.

This helps to keep recommended water levels in the lake. Heavy inflows into the dam have necessitated the release of the water to reduce the risk of dam wall failure and create space for more water expected from upstream of the Zambezi River in this second part of the season.

The two gates, opened to 50 percent levels will remain open for the next 10 days and will be releasing 1500m3 of water per second downstream.

The event was witnessed by scores of people from Zambia and Zimbabwe. Zambezi River Authority director projects and dam services engineer David Mazvidza, said the spilling of excess water was meant to bring the water levels below the operational rule curve.

This is the maximum amount of water that can be allowed in the dam at any particular time of the year.

Eng Mazvidza said they had delayed the opening of the flood gates this year to allow maintenance of the plunge that took place from between February and beginning of March this year.

“This is a process we do each year depending on the level of the water to the daily operational curve. Currently the water is 1,5m above the recommended level. The gates have been opened to 50 percent their capacity to ensure that they do not damage the repair works on the plunge pool.

“We fear opening of the flood gates to full capacity will cause erosion to the base of the plunge pool and pose a danger to the dam wall,” he said.

ZRA hydrologist Mr Pherry Mwiinga, said the authority expected minimal flooding downstream as the water in the river only expected to rise by less than a metre in narrow parts of the river channel.

We have been working with civil protection departments of both Zambia and Zimbabwe to inform people downstream of the opening of the gates and to make sure that they stay clear of the course of river.

“We are aware that some people will resist call to move away from river course until they are caught in the middle of the river.

“Infact this year we started giving notices as early as November of the opening of the flood gates and we believe our people are aware of possibility of flooding,” he said.

He said the authority still expected heavy floors from upstream of the river.

ZRA manages the Kariba Dam Complex and the water resources of the Zambezi River common to Zimbabwe and Zambia.