Rooting out alien vegetation to save water | Infrastructure news

Teams employed by Gamtoos Irrigation Board construct concrete weirs and other structures to conserve degraded peat wetlands in the Kromme River system. Image: Supplied

Teams employed by Gamtoos Irrigation Board construct concrete weirs and other structures to conserve degraded peat wetlands in the Kromme River system. Image: Supplied

Water saving activities in the Eastern Cape are finally beginning to pay off. Various Working for Water (WfW) projects around the province play a critical role in preserving run-off water, contributing to provincial dam levels.

These projects have been implemented across the Eastern Cape by Gamtoos Irrigation Board (GIB) and focus mainly on the clearance of alien vegetation and wetland rehabilitation. These projects also provide much-needed employment opportunities in rural communities.

Edwill Moore, GIB’s western region area manager, said although there has not been enough scientifically verifiable data to support claims of increased water flow, anecdotal evidence suggested a major improvement as a result of clearing activities.

“Numerous landowners will testify that after their property was cleared and maintained, the water flow increased dramatically, even during very dry periods,” Moore said.

First rolled out by GIB in 1999, the Kouga and Kromme River projects in particular are among the oldest in the Working for Water programme, initiated by the department of environmental affairs.

However, increasing water flow to the Kouga, Churchill and Impofu dams has become even more critical as water levels reach crisis point across several provinces in the country.

Clearing invasive species

In the Kouga catchment area, Moore said their primary focus was on clearing alien vegetation.

There are 12 teams. Each is made up of 14 members from local communities. These teams work to clear mainly Black Wattle (90% of the workload), Pine, Eucalyptus, Hakea and other less common species.

The project spans 282,000 hectares, extending from Haarlem in the west to Kouga Dam in the east, with the Kouga and Tsitsikamma mountains forming the northern and southern boundary respectively.

“To put it in perspective, that’s around 564,000 rugby fields,” Moore said.

“The water from this catchment area flows into the Kouga Dam, which supplies irrigation water to farmers in the Gamtoos Valley and is also the main water supply dam to the Nelson Mandela Bay Municipality,” he added.

Kromme River project

Running parallel to the Kouga project from The Heights in the west to Churchill Dam in the east is the 40,000 hectare Kromme River project area. Here GIB manages both alien vegetation clearing and wetland rehabilitation projects.

The water from this catchment flows into the Churchill and Impofu dams, which also supply Nelson Mandela Bay.

Although significantly smaller in area than Kouga, the Kromme workload was higher, with 13 teams of 14 working to clear vegetation, Moore said.

“The vision of the wetlands project is to facilitate the protection, conservation and rehabilitation of the degraded peat wetlands in the Kromme River System,” he explained. “Peat has the capacity to store up to 20 times its weight in water, which allows water to remain in the wetlands system for longer.”

Moore also explained that a slower release of water and consequent slow-down of run-off would allow sediment to settle more effectively, leading to a cleaner in-flow of water into the Churchill Dam.

“If the wetlands aren’t functioning properly, the water will just flow at a high rate, cost a lot more to purify and there will not be a constant flow of water into the dam,” he said.

To this end, he said GIB’s three wetland teams made it their priority to stop ongoing degradation and erosion by constructing various structures, such as gabions and concrete weirs, to prevent active head cuts from affecting the course and flow of the river.

Challenges

Moore said it had initially been challenging to get buy-in from local landowners, but that the long-term successes and benefits had instilled confidence and opened the door to greater co-operation.

“Over the past year, in both the Kouga and Kromme projects, it has been exciting to see these landowners being prepared to contribute to the cost of clearing operations, and we plan to build on this,” he said.

“The drought has naturally played a role,” he added. “Currently, we can’t address all the requests we get for clearing, but we are pleased to be working together.”

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