Nurturing nature’s functional beauty: Letšeng’s wetland and sponge projects

Mitigating the environmental impact from mining has always been a priority for Gem Diamonds. Towards the end of 2013, Letšeng initiated a wetland rehabilitation project, along the southern tributary of the Qaqa River.

Wetlands are lands saturated with water, either permanently or seasonally, and with distinct ecosystems. Wetlands provide many valuable services for humans and wildlife. They filter pollutants; reduce flooding and provide habitats for fish, wildlife, and indigenous plants.

Our wetland rehabilitation projects hold a three-fold purpose:

to rehabilitate natural wetlands;

to offset some of the negative environmental impact caused by mining; and

to provide a natural source of water treatment.

The Qaga engineered wetland was constructed downstream of the Qaga waste rock dump. In addition to rehabilitating an area previously mined for alluvial diamonds, it is anticipated that the wetland, perhaps the highest man-made wetland in southern Africa, will improve water quality through natural biological and chemical filtering in the wetland biomass. Since 2013, the wetland has continued to develop naturally, allowing for indigenous vegetation to flourish. Through weekly volume control and water quality monitoring, there has been slow but steady progress with regards to wetland establishment and water quality improvement. We anticipate that results will improve as the wetland continues to establish itself over a longer period.

In 2015, Letšeng partnered with the Lesotho government on the sponge project, to protect and conserve the ’sponges’ or wetlands in the Khubelu catchment through the sustainable management of these wetlands.

The wetlands are crucial to the sustenance of the ecosystems and biodiversity in the catchment, which provides human beings with sources of livelihoods, sustain livestock and regulate water storage, quality, and flow. These benefits are not only important for the livelihoods of the local communities, but also for the growth of the economy of Lesotho. Conservation of the wetlands is expected to reverse the losses that are already experienced due to the degradation of the wetlands and ensure a sustainable flow of the services/benefits from the wetlands.

One major challenge facing this valuable natural resource, however, is that livestock overgrazing and trampling are affecting the rate of erosion of the wetlands. Overgrazing harms wetlands through soil compaction, removal of vegetation, and stream bank destabilisation. Wetlands offer some of the best forage for livestock as well as a water source and cover, so livestock tend to spend a disproportionately large time in wetlands.

Proper management of wetlands rests on effective rotational grazing that allows the wetlands to rest. The initial stages of this project, therefore, have involved educating local herdsman about sustainable grazing practices, ensuring that areas are grazed evenly, decreasing the risk of erosion. Following better grazing practices, the groundwater level is expected to increase, allowing the wetland to rehabilitate and sustain itself naturally.

 
Letšeng Diamond Mine, Bongani Ntloko working on the rehabilitation trials.   Letšeng Diamond Mine, artificial wetland project.